Editor-in-Chief: Paolo RussoPast Editor-in-Chief: Fridtjof Nsslin

PhysicaMedicaEuropean Journal of Medical PhysicsThe official journal of the

Associazione Italiana di Fisica Medica,European Federation of Organizations for Medical Physics,Irish Association of Physicists in Medicine andSocit Franaise de Physique Mdicale

Abstracts from the 8th European Conference on Medical Physics

September 11th13th, 2014Athens, Greece

1.2671.849

Volume 30 Issue S1 September 2014 ISSN 1120-1797

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Under the Auspices and Support of the Greek National Tourism Organisation

Abstracts from the 8th European Conference on Medical Physics

September 11th13th, 2014Athens, Greece

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8 Invited Lectures

Oral Presentations 23

E-Posters with presentation

E-Posters 82

52

Physica Medica:European Journal of Medical Physics

Volume 30, Supplement 1, 2014

The official journal of the European Federation of Organizations for Medical Physics, Associazione Italiana di Fisica Medica, Socit Franaise de Physique Mdicale

and Irish Association of Physicists in MedicinePhysica Medica is recognised by the European Physical Society

CONTENTS

Le

the large and increasing number of procedures and the large involve-ment of professionals outside the radiology department have partiallyimpaired these efforts with the results, as demonstrated by recentstudies, that the practice in general has not yet reached acceptableoptimisation levels.For patient exposures, national and international surveys are showinglarge variations in the practice, n the performance of radiological equip-ment, in the technical protocols and, nally, in the patient doses. The

of half yearly tests.Every day, the centres make 2 acquisitions of a ho-mogenous test object that is rotated over 180 between the 2 exposures.Raw data are sent to a DICOM receiver program, analysed and sent to theQC platform of our centre (product of qaelum NV, Belgium). The centrestest also the monitors with a variable test pattern, that shows every daydifferent low contrast characters to allow the testing of the characteristicsof monitor and reading room. The same platform (qaelum NV, Belgium) isused for quality supervision.

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Physica Medica 30S1 (2014)(IR) and cardiology (IC) practice is the objective of more than 20 years ofnational and international studies, recommendations and actions. But,

During the lecture we will show the software networking platform fordaily QC supervision and the link between these daily data and the resultsInvited

PATIENT DOSE AND IMAGE QUALITY: ROLE OF MEDICAL PHYSICISTS

Francis R. Verdun. Institute of Radiation Physics (IRA), CHUV, Lausanne,Switzerland

Introduction: Radiation protection in medicine is becoming a real chal-lenge when dealing with the use of technologies such as CT, uoroscopyand PET/CT. In Switzerland, since January 2012, medical physicists have tobe involved with the medical team dealing with high dose proceduressuch as the ones mentioned above to strengthen the optimization process.This new role for medical physicists has a strong potential in the frame-work of medical radiation protection. The aim of this presentation is toshow, using a few examples, how the introduction of this new legalrequirement can improve radiation protection not only of the patient butalso of the staff.Material and Method: Our Institute is in charge of consulting more thantwenty-ve centers (50 CT units; 10 uoroscopy units used for interven-tional radiology and cardiology and 5 PET/CT units). These units have beenmonitored using common protocols that, while integrating some standardquality assurance measurements, mainly focus on the way the unit is usedin practice.Results: A wide variation of protocols is applied for comparable in-dications. For example, patient doses for a standard abdominal CT exam-ination can vary by a factor of 23. Cumulative doses over 5 Gy can be verycommon in some centers without taking any special measures to informthe patient of the possibility to develop tissue reactions. To improve thepresent situation, several measures should be introduced: standardizationof the CT protocols nomenclature, standardization of the interventionalprocedures names, and denition of clinically relevant image qualitylevels.Conclusion: The implication of medical physicists in radiology and nu-clear medicine has the potential to improve the optimization of radio-logical procedures. As opposed to radiation therapy, precision in dosemeasurements should not be the main role of medical physicists. She/heshould part of the medical team to improve the standardization of theexaminations or procedures nomenclature and to develop a strategy toprovide the physician with clinically relevant measures of image quality.Then one could work on the balance between diagnostic information andrisk.

DOSE REDUCTION IN INTERVENTIONAL RADIOLOGY & CARDIOLOGY

Renato Padovani. ICTP Abdus Salam Int. Centre for Theoretical Physics,Trieste, Italy

Optimisation of patient and staff exposure in interventional radiology

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optimization instrument of the DRLs, assessed only for few procedures andmainly for IC, is rarely implemented and used. The ICRP is putting newefforts in redening the methods to assess and use DRLs as a tool to limitnon acceptable dose levels and helping in the optimization process.For staff exposure, ISEMIR project has highlighted a poor monitoringpractice in IC bringing to important underestimation of doses and, newchallenges for eye lens dosimetry are coming from the 2011 ICRP state-ment recommending a new and lower eye lens dose limit. Staff moni-toring, aiming to assure the compliance with the dose limits, is in generalaffected by large uncertainties for staff exposed near the radiation sourceand partially protected. These uncertainties are larger for lens eyedosimetry for the use of protective glasses and for the laterality and thefrom-below direction of the irradiation. These large uncertainties, whenthe doses are of the same order of magnitude of the limit as happen foreyes, are not assuring the compliance with the new dose limit. As anexample of advanced dosimetry, the active dosimetry technology canimprove staff monitoring providing instant information on exposures,allowing the integration of staff and patient exposure data and, nally,supporting staff education.To progress in the staff optimization it will be necessary to advance indosimetry methods, harmonise dosimetry practice, to develop interna-tional databases to support benchmarking, promote optimized procedureprotocols, and require harmonized and certied education and training.

QA IN DIGITAL MAMMOGRAPHY: LOCAL ACTIVITIES AND REMOTECONTROL

Hilde Bosmans. KU Leuven, Department of Imaging and pathology, Belgium

Quality assurance in mammography should ensure the optimal balancebetween X-ray dose and image quality. The European Guidelines on QA inmammography include a protocol for digital mammography equipmentthat allows to evaluate the X-ray tube, detector, settings of the automaticexposure control, the monitor and overall image quality. There are no in-dications as to how assure the quality of the clinical image quality. Theprotocol recommends that daily or weekly quality control tests should becentrally supervised.Our regional government has required to perform breast cancer screeningin line with the chapter on physico-technical tests. To do so, we imple-mented yearly and half yearly tests for digital mammography and dailytests of the X-ray system and the monitors. AQ new X-ray modality has topass a type test procedure rst. Seen the large number of mammographysystems in our region, the daily and weekly procedures have been largelyautomated.We have contracts for QA activities on 103 mammography units, includingCR and DR systems of all major vendors and 3 more lm-screen systems.

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Medica 30S1 (2014)Recently, 2 scientic papers have conrmed good performance of ourscreening program. These studies are also a conrmation for the group ofphysicists who have worked at a strict physic-technical quality assurancesystem. The networking approach could be copied in other countries ofcourse. Session number of session in which the abstract is presented: Scienticsession: QA in radiology; Thursday afternoon, 14.30 e 15.30 Session title of session in which the abstract is presented

FULLY AUTOMATED TREATMENT PLAN GENERATION IN DAILY ROUTINE

B. Heijmen, P. Voet, M. Dirkx, A. Sharfo, L. Rossi, D. Fransen, J. Penninkhof,M. Hoogeman, S. Petit, J.-W. Mens, A. Mendez Romero, A. Al-Mamgani, L.Incrocci, S. Breedveld. Erasmus MC Cancer Institute, Rotterdam, TheNetherlands

Background: Currently, treatment plans are generated by dosimetristsusing a trial-and-error procedure. The process may take several hours andplan quality is dependent on the skills and experience of the dosimetrist,and on allotted time. We have developed and clinically introduced a sys-tem for fully automatic plan generation, using lexicographic multi-criterialoptimization to replace the labour-intensive and operator-dependent trial-and-error approach.Materials and Methods: For each patient, the treatment plan is fullyautomatically generated by the clinical treatment planning system(Monaco, Elekta AB), based on a patient-specic template that is auto-matically pre-generated with our in-house lexicographic multi-criterialoptimizer (Erasmus-iCycle, Med Phys. 2012; 39(2): 951). Automatic plangeneration in Erasmus-iCycle is based on a wishlist with hard constraintsand treatment objectives with assigned priorities. For each treatment site(e.g. H&N cancer), a single xed wish-list is used for all patients. In case ofIMRT, Erasmus-iCycle can be used for integrated beam prole optimizationand (non-coplanar) beam angle selection.Results: In a prospective clinical H&N cancer study, radiation oncologistsselected the AUTO-plan in 97% of cases rather than the MANUAL-plangenerated by trial-and-error (IJROBP 2013; 85(3): 866-72). For a group of44 cervical cancer patients, dual-arc VMAT AUTO-plans were superior toMANUAL-plans generated by an expert cervical cancer planner, spendingmany hours; reduced small bowel V15Gy, V45Gy, and Dmean, bladder Dmean,and rectum Dmean, p

Abstracts / Physica Medica 30S1 (2014) 3concept of lateral buildup ratio (LBR) as an avenue to evaluate electronlater scatter equilibrium and compute dose per MU for those elds. Finally,it gives some common clinical examples where electron beam dosimetryare applied.This presentation will try to provide guidance to the audience for betterunderstanding the methods and recommendations in TG-70. In addition,will describe how to link the absolute dose calibration recommendationsof TG-51 to the relative dose measurements of TG-71.

TOWARDS DAILY ADAPTED PROTON THERAPY

Tony Lomax. Centre for Proton Therapy, Paul Scherrer Institute, Switzerland

Proton therapy using Pencil Beam Scanning (PBS) is a highly conformal andexible form of radiotherapy. However, anatomic changes of the patientduring the course of therapy are a major challenge due to the potentiallymajor changes in proton ranges that can result. The challenge is evengreater given that such changes can occur on a daily basis and currentsoftware systems and workows in radiotherapy are too slow to react tosuch changes. In order to fully exploit the highly conformal characteristicsof PBS proton therapy therefore, methods for the daily adaption of protontherapy need to be developed, a concept we call Daily Adaptive ProtonTherapy (DAPT). The concept of DAPT is to work towards a exible andfully automated workow for PBS proton therapy, with the aim of imaging,planning and delivering a plan-of-the-day for patients on a daily basis. Inorder to achieve this, the time between the imaging of the patient anddelivery of the plan has to be reduced to a maximum of 1-2 minutes. Withthe in-room imaging capabilities of the PSI Gantry 2, and the inherentexibility of PBS proton therapy, we believe we already have the idealtreatment machine for the implementation of DAPT. However, the chal-lenges are more computational and workow oriented than technological.In order tomove towards a DAPTapproach for instance, image registration,planning and optimisation procedures must be made computationallyefcient and fully automated. In addition, efcient and informative toolsneed to be developed that will allow clinical staff to review these plans-of-the-day, as well as to allow for fast, but nevertheless safe, quality assur-ance checks of the plans. For instance, with the introduction of DAPT typeapproaches, it will be impossible to perform patient or eld specicdosimetric verications, and other, automated methods for checking thedelity of treatments and treatment control les will need to be devel-oped. Thus, there are many challenges to be met before DAPT will becomea reality. However, we rmly believe that moving in this direction is thenext major advance in clinical proton therapy, and its introduction couldhave at least as large an impact on current clinical practice with protons asthe introduction of Intensity Modulated Proton Therapy. Indeed, one couldargue that PBS proton therapy, with its exible and automatedworkow, ispre-destined for the DAPT concept.

FLUORESCENT NUCLEAR TRACK DETECTORS AS A TOOL FOR ION-BEAMTHERAPY RESEARCH

S. Greilich a, O. Jakel a,b,c. aGerman Cancer Research Center (DKFZ), Divisionof Medical Physics in Radiation Oncology, Im Neuenheimer Feld 280, 69120Heidelberg, Germany; bHeidelberg University Hospital, Department ofRadiation Oncology, Im Neuenheimer Feld 400, 69120 Heidelberg,Germany; cHeidelberg Ion-Beam Therapy Center (HIT), Im NeuenheimerFeld 450, 69120 Heidelberg, Germany

Originally designed for optical storage, uorescent nuclear track detectors(FNTD) based on Al2O3:C,Mg single crystals contain aggregate F2

2+(2 Mg)color centers that show permanent radiochromic transformation whenbombarded with ionizing radiation. Transformed centers produce highyield uorescence at 750 nmwhen stimulated at 620 nm and a short (755ns) lifetime. This enables non-destructive readout using confocal laser-scanning microscopes (CLSMs, Akselrod and Sykora, 2011). Since the in-tensity signal depends on the local energy deposition, 3D particle trajec-tories through the crystal can be assessed. Together with the excellentsensitivity Al2O3:C,Mg this enables the derivation of information on tracklocation, direction, energy loss, etc. over the entire particle and energyrange found in ion beam therapy. Effects such as projectile fragmentationand secondary electron trajectories can be studied in detail with diffrac-tion-limited resolution (Greilich et al., 2013). Due to their biocompatibility,autoclavability and since post-irradiation chemical processing is notneeded, FNTDs can show signicant superiority to existing technologiessuch as plastic nuclear track detectors (PNTDs, e.g. CR-39).Our group studies the FNTD technology for application on three mainelds: Fundamental dosimetry quantities (w-value, I-value) in ion beams:FNTDs allow determining particle uence and range with very high ac-curacy (Osinga et al., 2013, Klimpki et al., 2013). In-vivo track-based assessment of dose to organs at risk during therapy:FNTDs represent one of a few systems that enable biological dose esti-mation which is the essential predictor for clinical outcome in ion beamtherapy. In addition, FNTD are small, resilient, wireless and biocompatibleand can be therefore used within phantoms, animal models or evenpatients. Radiobiology: our group was the rst to use FNTDs as substrate for cell(Cell-Fit-HD, Niklas et al., 2013). This enables to correlate microscopicphysical parameters and subcellular/cell response both in xed and livingcell and study cellular processes fundamental to ion beam radiotherapythat are hitherto little understood.The talk will present the basic principle of FNTD technology, our groupstechnical implementation as well as the latest methodological de-velopments and application results.References1. Akselrod MS, Sykora GJ: Fluorescent nuclear track detector technologyeA new way to do passive solid state dosimetry. Radiat Meas 2011,46:1671e1679.2. Greilich S, Osinga J-M, Niklas M, Lauer FM, Klimpki G, Bestvater F, BartzJA, Akselrod MS, Jakel O: Fluorescent Nuclear Track Detectors as a Tool forIon-Beam Therapy Research. Radiat Meas 2013, 56:267e272.3. Klimpki G, Osinga J-M, Herrmann R, Akselrod MS, Jakel O, Greilich S: IonRange Measurements using Fluorescent Nuclear Track Detectors. RadiatMeas 2013, 56:342e346.4. Niklas M, Abdollahi A, Akselrod MS, Debus J, Jakel O, Greilich S: Sub-cellular spatial correlation of particle traversal and biological response inclinical ion beams. Int J Radiat Oncol 2013, 87:1141e1147.5. Osinga J-M, Brons S, Bartz J a, Akselrod MS, Jakel O, Greilich S: AbsorbedDose in Ion Beams: Comparison of Ionisation- and Fluence-Based Mea-surements. Radiat Prot Dosimetry 2014.

INCREASING PRECISION IN PARTICLE THERAPY: IN VIVO DOSIMETRYAND BEYOND

C. Richter a,b,c,d, G. Pausch a,b,d, J. Seco e, T. Bortfeld e, W.Enghardt a,b,c,d. aOncoRay e National Center for Radiation Research inOncology, Faculty of Medicine and University Hospital C.G. Carus,Technische Universitat Dresden, Germany; bDepartment of RadiationOncology, Faculty of Medicine and University Hospital C.G. Carus,Technische Universitat Dresden, Germany; cGerman Cancer Consortium(DKTK), Dresden, & German Cancer Research Center (DKFZ), Heidelberg,Germany; dHelmholtz-Zentrum Dresden-Rossendorf, Germany;eMassachusetts General Hospital and Harvard Medical School, Departmentof Radiation Oncology, Boston, MA, USA

The proton dose distribution including the steep dose gradient at the endof range not only allows a better sparing of normal tissue. It also enforcesthe need of a precise control of the dose deposition to ensure the correctposition of the dose gradient to take full advantage of the superior capa-bilities of proton therapy. Otherwise, factors like tissue heterogeneities,patient positioning errors and intra-fractional motion can cause high un-certainties in proton distal range resulting in a failing tumor coverage or/and an unnecessary high dose deposition in healthy tissue due to the use ofextended margins. Therefore, an in vivo verication or any other control ofproton range and delivered dose distribution is highly desirable.Several in vivo dosimetry approaches will be presented and compared.They rely on either nuclear interactions of the beam with the irradiatedmatter (In beam-PET and prompt g-ray imaging) or on the visualization of

Abstracts / Physica Medica 30S1 (2014)4biological processes induced by radiation, e.g. with MRI. The most expe-rience exists for in beam-PET. In Dresden, the current research focuses ontime-resolved acquisition (4D-PET) and on automated detection of rangedeviations. In contrast, prompt gamma ray imaging is a relatively new anddynamic eld of research. Several prompt g-ray imaging detector systemsare under development in various research centers around the worldbased on active- as well as passively collimated systems. A complementaryapproach, based on the time spectrum of the g-ray emission, is investi-gated in Dresden. First promising results will be presented in the talk.However, so far there is no clinical application of prompt g-ray based invivo dosimetry. In contrast, radiation-induced biological changes havebeen used in clinical trials at the Massachusetts General Hospital in Boston(MGH) for range verication in both, spine and liver. A recent study, alsocarried out at MGH, aims at a better understanding of when those treat-ment related changes in the liver begin to appear.Instead of assuring a safe and precise treatment by measuring the in vivodose deposition, another approach is to decrease dose deposition un-certainties before beam delivery. This can be done in several ways: Oneapproach tries to increase the robustness of the treatment plan againstdifferent types of uncertainties. This can be realized by including therobustness in the optimization and penalizing treatment plans with a dosedeposition very prone to expected deviations. A completely differentmethod for increasing dose deposition precision is based on online im-aging during treatment: If the exact patient geometry would be known forevery time point, the delivered dose deposition could be calculated andeven adapted online if necessary. Online imaging could be performed withMRI scanners integrated in the treatment room in analogy to the combinedMRI-linac approaches. At the moment this is a eld of intense researchwith quite impressing progress.At this point it is not clear which of the different methods to increaseprecision in particle therapy will nd their way in routine clinical appli-cation. Nevertheless, the demand and the potential of these methods areunquestionable.

MONTE CARLO MODELING AND IMAGE-GUIDANCE IN PARTICLETHERAPY

G. Dedes, K. Parodi. Department of Medical Physics, Ludwig MaximiliansUniversity, Munich, Germany

The use of protons and heavier ions in external beam therapy offersdistinctive advantages with respect to conventional radiotherapy usingelectromagnetic radiation. The physical selectivity of ions with the char-acteristic Bragg curve can enable high tumor-dose conformity, resulting inlower irradiation of healthy tissues and critical organs in close vicinity tothe target volume. Moreover, the higher relative-biological-effectiveness(RBE), especially in the case of heavier ions, can offer improved controlprobability for radioresistant tumors. In this context, Monte Carlo (MC)particle transport and interaction methods are increasingly employed inclinical and research institutions as vital tools to support several aspects ofbeam modeling, treatment planning and quality assurance of high preci-sion ion beam therapy.This talk will review the role of MC methods in selected applications inparticle therapy. Drawing on own experience at different European particletherapy facilities, the ne tuning of MC parameters for beammodeling willbe presented. In addition, based on ongoing studies and collaborations, wewill give an overview on thewide range of MC applications aiming at noveltools for image guidance and treatment planning. These include the sup-port to the development of heavy ion and proton computed tomography,as well as the direct usage of MC-data in the inverse planning process,featuring calculations of both absorbed and biologically weighted dose.Development and validation of new solutions based on clinically estab-lished imaging modalities for adaptive strategies in particle therapy will bealso addressed, together with research efforts to support unconventionalimaging-based techniques detecting secondary radiation for in-vivoconrmation of the actual treatment delivery. Finally, the application ofMonte Carlo tools in the emerging research area of laser driven ion ac-celeration for medical application will be briey exposed.Parts of this work have been supported by the DFG Cluster of Excellence

MAP (Munich-Centre for Advanced Photonics), the DFG Project on IonRadiography and Tomography, the FP7 Project ENVISION, and the BMBFProject SPARTA.

IMAGE GUIDANCE FOR ADAPTIVE RADIOTHERAPY: IS THERE STILL ANEED FOR SURROGATE SYSTEMS?

Torsten Moser. Im Neuenheimer Feld 280, 69120, Heidelberg, Germany

In conformal radiation therapy, accurate and reproducible patient setup isrequired. In this regard, initial setup errors, as well as day-to-day setupvariation, still poses a clinically relevant problem. The available anatomic(internal) information of the patient, however, relies on the images of theplanning CT, acquired up to weeks prior to treatment and does not reectchanges during the actual treatment. To correct in the actual situation, themost reliable information is obtained by 3D-imaging techniques like conebeam CT. Adaptive treatment techniques, moreover, adds a furthercomponent to the treatment chain, the feed-back. Again by daily imageguidance, changes that occur during the treatment can be detected andhandled. Meanwhile, most linear accelerators are able to acquire images(eg, kilovoltage/megavoltage setup images or cone beam computed to-mography [CT] scans) that allow correlation of the actual patient positionwith that during treatment planning CT. By the use of such image guidedradiation therapy techniques, the potential benet for the patient has to beweighed against the additional risk associated with the imaging dose.For this reason, non-radiologic techniques to verify the setup position ofthe patient are of great interest. As such developments, there are varioussystems available that provide also information of motion and/or position.There are devices available where electromagnetic markers have to beimplanted into the patient or technologies where other informations areused to generate signals that can be used for position or motion correction.One of the latter are optical surface imaging systems. Optical surface im-aging systems are able to reconstruct a 3-dimensional (3D) surface modelrelative to the isocenter position. A setup correction is calculated byregistering actual images with reference images stored in the system be-forehand. Although the technical accuracy of such systems has been shownto be quite high, their suitability for clinical application depends onadditional aspects, in particular on a xed spatial relation between thesurface and target region. To analyze this, setup corrections from a surfaceimaging systemwere evaluated in 120 patients. As a measure of reliability,the corrections derived by the optical system were compared with thosefrom 3D radiologic imaging, which is the current gold standard in imageguided radiation therapy. We found a dependence on the target region andthe used reference image modality. Therefore, additional radiologic im-aging may still be necessary on a regular basis (e.g., weekly) or if thecorrections of the optical system appear implausibly large. Nevertheless,such a combined application may help to reduce the imaging dose for thepatient.

SMALL PHOTON FIELD DOSIMETRY: PRESENT STATUS

Maria M. Aspradakis. Cantonal Hospital of Lucerne, 6000 Lucerne 16,Switzerland

Background: IPEM report 1031 summarised existing knowledge on thephysics and challenges in the dosimetry of small MV photon elds,reviewed available detectors for dose measurement, gave recommenda-tions based on existing knowledge and experience, explained the need ofcommissioning treatment planning systems for small eld applicationsand pointed out directions for future work. This presentation reports onrecent developments.Materials and Methods: A megavoltage (MV) photon eld is dened assmall when either the eld size is not large enough to provide lateralcharged particle equilibrium at the point of dose measurement or thecollimating device obstructs part of the focal spot as viewed from thatpoint. The overlapping penubras from opposing jaws result that the fullwidth half maximum of the dose prole (FWHM) no longer matches thecollimator setting. Thus, the conventional dention of eld size in terms ofFWHM breaks down. The measurement of dosimetric paraments in suchnon-at narrow elds becomes a challenge because most detectors are too

large to resolve the non at dose prole or that they perturb uence in a

a Meway that using available perturbation factors is not appropriate. Further-more, changes in energy spectrum with eld size, the fact that on somemodern radiotherapy equipment conventional reference conditionscannot be realised or that the attening lter is not present, means thatcurrent dosimetry codes of practice do not provide recommendations fordosimetry in such elds.Results & Discussion: The new formalism for dose determination in smalland non-standard photon elds developed by the IAEA/AAPM isexplained2. Some results on detector-specic beam quality correctionsfactors are presented.References1. Aspradakis, M.M., Byrne, J. P., Palmans, H., Conway, J., Rosser, K., War-rington, A. P., Duane, S. IPEM report 103: 'Small Field MV Photon Dosimetry'.2010, York, UK: Institute of Physics and Engineering in Medicine (IPEM).ISBN 978 1 903613 45 02. Palmans, H, Dosimetry of small elds: Present status and future guidelinesby IAEA, Radiotherapy & Oncology, Vol 111, Supp 1, April 2014, ISSN 0167-8140

MEDICAL PHYSICS CHALLENGES WITHIN THE MICROBEAM RADIATIONTHERAPY (MRT) PROJECT

E. Brauer-Krisch a,f, C. Nemoz a,f, T. Brochard a,f, M. Renier a,f, H.Requardt a,f, R. Serduc b,f, G. LeDuc a,f, A. Bravin a,f, S. Bartzsch c,f, P.Fournier d,a,f, I. Cornelius d,f, P. Berkvens a,f, J.C. Crosbie d,f, M.L.F.Lerch d,f, A.B. Rosenfeld d,f, M. Donzelli a,c,f, U.Oelfke c,f, A. Bouchet e,f, H.Blattmann g,f, B. Kaser-Hotz h,f, J.A. Laissue i,f. aEuropean SynchrotronRadiation Facility, B.P.220, F-38043 Grenoble Cedex, France; bINSERM unit836, CHU Grenoble, Grenoble, France; cIm Neuenheimer Feld 280,69120Heidelberg,Germany; dCMRP, Northelds Ave., Wollongong, 2500, NSW,Australia; eUniversitat Bern Institut fr Anatomie Baltzerstrasse 2CH-3000Bern 9, Switzerland; fCHU Grenoble, Grenoble, France; gNiederwiesstr. 13c5417 Untersiggenthal, Switzerland; hAnimal Oncology and Imaging Center,Rothusstr. 2, CH-6331 Huenenberg/CH,.Switzerland; iUniversity of Bern,Faculty of Medicine, Murtenstrasse 11, CH-3010 Bern, Switzerland

Background: Microbeam Radiation Therapy (MRT) uses a spatially frac-tionated ltered white X-ray beam from a high energy wiggler Synchro-tron Source (energies 50-350keV) with extremely high dose rates (up toabout 20kGy/s). The typical planar beam width in an array is 25-100mmwith 100-400mm wide spaces between beams. Such beams are very welltolerated by the tissue, even the high peak doses delivered in the path ofthe microbeams, when respecting a dose prescription in the valley thatcorresponds to a dose used of conventional Radiation Therapy (RT) con-verted to a single exposure . The superior tumor control when compared tothat realized by conventional RT is achieved by differential effects of MRTon the normal tissue vasculature versus the tumor vasculature.Materials and Methods: The MRT technique has been technically set up,tested and successfully applied during the last 20 years on various tumormodels. Presently, the project is mature enough to be used for the treat-ment of spontaneous tumors in pets. Unied efforts from several teamswith very different expertise now permit Microbeam Radiation Therapy inanimal patients with a high degree of safety, in pursuit of the ultimate goalof clinical applications in humans.Results: The MRT trials for animal pets as tumor patients required sub-stantial work for developing, upgrading and progressively implementinginstrumentation, dosimetry protocol, as well as the crucial patient safetysystems. Progress on the homogenous dose measurements using ionisa-tion chambers and Alanine dosimetry as well as the comparison of highresolution dosimeters with the dose calculations based on a novel tumorplanning system will be summarized. A general overview on the differentachievements will be presented as well as a vision for possible humantrials.

TEXTURE AS IMAGING BIOMARKER

Costaridou Lena. Department of Medical Physics, School of Medicine,University of Patras, Rion Patras 26504, Greece

Abstracts / PhysicQuantitative image analysis involves derivation of quantitative measures(extraction of image features), aiming to capture image manifestations ofconsidered. Representative texture analysis approaches will be reviewedacross imaging modalities, with reference to methodological and techno-logical aspects and challenges. The advent of multimodality imaging withnear isotropic 3-dimensional spatial resolution modalities, includinganatomical and functional modalities, is expected to enhance character-ization and quantication of naturally occurring textures, as well as theirscale and orientation properties, while casting insight to texture dynamics,provided by imaging tissue volume times series (spatiotemporal data).

TECHNICAL CHALLENGES AND CLINICAL RESEARCH APPLICATIONS OFULTRAHIGH FIELD MRI

AndrewWebb. Leiden University Medical Center, Radiology Department, TheNetherlands

With the rapid spread of 7 Tesla whole body MRI systems throughout theworld there has been signicant recent progress in both clinical andclinical research applications. Although predominantly in the neurologicalarea, there have also been many developments in the areas of musculo-skeletal, cardiac and ocular imaging. Increased magnetic susceptibilitycontrast, enhanced magnetic resonance angiography, and much highersignal-to-noise in spectroscopy and heteronuclear imaging/spectroscopyhave been the driving forces for much of this progress. The major chal-lenges have been, and continue to be, increased image inhomogeneity,power deposition, and motion-induced artifacts. Many hardware advanceshave already been necessary to deal with these problems, and many futureadvances are required to keep the eld moving forward.Examples which will be presented include: (i) the use of navigator echoesand phase imaging for high resolution MRI in Alzheimers patients, (ii) theuse of high dielectric materials to improve neuroimaging and spectroscopyat high eld, (iii) diffusion weighted metabolite spectroscopy in the brain,(iv) high eld cardiac and musculoskeletal imaging, and (v) the design ofnew types of RF coil specically for high eld.

DOSIMETRY IN SUPPORT OF PATIENT PROTECTION IN DIAGNOSTICRADIOLOGY - A VALEDICTORY VIEW FROM THE UK

Dr Paul C. Shrimpton. Formerly Leader of Medical Dosimetry Group, PublicHealth England, Chilton, OX11 0RQ, UK

Invited lecture in relation to EFOMP Medal Award CeremonyThe increasingly widespread use of x-rays in diagnostic radiology providesnot only enormous benets to patients, but also signicant radiationexposure for populations. The protection of patients against potential ra-diation harm requires the elimination of all unnecessary x-ray exposure inrelation to effective clinical diagnosis. Dosimetry is an essential manage-ment tool for patient safety by allowing the assessment of typical radiationrisks in support of the justication of procedures, and the routine moni-toring and comparison of typical doses in pursuit of the optimisation ofpatient protection. Periodic assessment of patient doses should form anintegral part of quality assurance in x-ray departments and is best based onpractical measurements that provide useful characterisation of patientexposure, such as entrance surface dose, dose-area product and, for CT,volume-weighted CT dose index and dose-length product. Mean valuesunderlying pathophysiological processes, with the ultimate goal to identifyimage-based biomarkers and improve patient-specic disease manage-ment. While features capturing lesion contrast and shape, also mimickingradiologists used image attributes, have been extensively studied in theframework of image-based computer aided diagnosis texture analysis, notdirectly intuitive to radiologists, is an emerging approach. In addition, thetissue appearance modeling and classication task has been recentlyenriched, encompassing tasks, such as prognosis, monitoring diseaseprogression and response to therapy, as well as cancer risk assessment.Prognosis imaging biomarkers assess neoplasm aggressiveness, in terms oftheir relationship to pathology and molecular classication, while treat-ment response imaging biomarkers could help early identication of re-sponders/non responders to neo-adjuvant chemotherapy schemes prior tosurgical decisions. In this review, texture analysis methodologies exploitedtowards the identication of potential imaging biomarkers will be

dica 30S1 (2014) 5determined in a department for these practical dose monitoring quanti-ties, from patient samples for each type of examination and patient group,

Badly written papers, not complying with requirements and including

Abstracts / Physica Medica 30S1 (2014)6can form the basis not only for estimates of typical organ and effectivedoses to reference patients utilising appropriate coefcients, but also localdiagnostic reference levels (DRLs). DRLs represent a pragmatic mechanismfor promoting continuing improvement in performance by facilitatingcomparisonwith national values and practice elsewhere. The developmentand application of DRLs in the UK over the last 30 years, within a coherentframework for patient protection that has included periodic nationalsurveys for conventional x-rays and CT, has successfully helped reduceunnecessary exposures, with national DRLs for many examinations havingfallen by a factor 2.

HOW TO OPTIMIZE EXPOSURES USING RADIOBIOLOGY AS A GUIDE

Klaus Trott, Vere Smyth, Andrea Ottolenghi. Department of Physics,University of Pavia, Via Bassi 6, 27100, Pavia, Italy

Medical radiation exposures associated with the diagnosis and treatmentof diseases are, besides natural background irradiation, the main source ofradiation burden to mankind and may lead to an increased risk of variousdiseases such as cancer, cardiovascular diseases, developmental disordersand heritable health injury. Concepts for radiation risk estimation andreduction were developed by ICRP, yet they do not apply to individualpatients but to the population at large. They are designed to be used asguidelines for planning safe procedures e.g. in industry and publichealth. Population risk estimates are based on mean doses to a list ofcritical organs and on tissue weighting factors. The estimation of radia-tion risks for individual patients, however, has to be based on the deter-mination of anatomical dose distribution within the exposed organs emean doses may be meaningless. Even within the same organ, pathology,pathophysiology and pathogenesis differ between different potentialhealth complications from medical radiation exposures of the differentorgans. They depend on dose to critical structures and subvolumes, on ageand sex of the exposed patient and most likely also on genetic predispo-sition and life style factors. Both, for diagnostic exposures and therapeuticexposures of the individual patient, estimations of health risks need to bebased on radiobiological mechanisms of pathogenic pathways. Models ofrisk estimation in particular those from therapeutic exposures are notspecic for particular organs but for particular clinical manifestation ofradiation-induced disorders and diseases. Moreover, dose volume histo-grams are of little value in these estimates since anatomy is more impor-tant than volume. Several exposure scenarios in diagnostic and therapeuticradiology will be discussed to explain the problems and suggest possibil-ities to solve the problems.Acknowledgments. This work was partially funded by EU (EC Contract FP7605298, EUTEMPE-RX).

HOW TO PUBLISH A PAPER IN A PEER-REVIEWED JOURNAL

David Thwaites. Institute of Medical Physics, School of Physics, University ofSydney, NSW2006, Australia

Publication of work is necessary to move the eld forward. Using experi-ence as an author, reviewer, editorial board member and editor, someobservations are summarized onwriting a paper, submitting it and gettingit published, focussing on what makes a good paper and hence likely to beacceptable.First, consider yourmainmessage and hencematerial selection andwritingow so that this is clear. Make the introduction relevant towhere the workts into current related research, going quickly from generalities to spe-cics. Even good well-presented work will not get into high-impact-factorjournals unless it is clearly novel and/or signicant. Methods should allowthework to be repeated; ask yourself if they are clear and complete. Explainacronyms. Results should clearly tie gures and tables to text. Conclusionsshould relate back to the key message and be veriably supported by re-sults. Discussion and conclusions should not just be re-stated results!Ask a colleague, unconnected with the work, to read the nal draft paperand give comments on clarity. If they can't understand it, neither will thereferees! Re-read it yourself after a time gap. Check journal requirementsand comply! Hastily prepared submissions are usually poorly prepared!mistakes, eg in references, immediately give the impression that the workmay also be poor. Work with experienced authors initially (eg supervisor).Look critically at papers you read and notewhat you thinkworkswell. Newwriters can learn good practice by example. Good luck!

REASONS FOR REJECTION

Paolo Russo. Universita di Napoli Federico II, Naples, Italy

Rejection of a paper refers to the decision of the Editor of a scienticJournal not to accept the submitted manuscript for publication in thatJournal. This condition may occur in any phase of the paper evaluationprocess, but mostly occurs at the end of the rst round of the peer-reviewprocess, i.e. when one of two experts, asked for their independentopinion, suggest reasons for acceptance, revision or rejection of themanuscript. Typically, in the case of a negative peer-review, the AssociateEditor expresses a recommendation (e.g., reject) for the Editor-in-Chief,who takes the nal decision. The rejection rate of a Journal, i.e. the ratio ofthe number of rejected to the number of evaluated manuscripts, has beenseen to increase over the last years in many well-reputed scienticJournals, also in the case of medical physics Journals, and this has causedconcern both in the Journal's Editorial Boards, and in the authors' com-munity. For example, for the Journal Physica Medica (European Journal ofMedical Physics, EJMP) the rejection rate is such that only about onemanuscript out of three is accepted for publication. This has thenprompted various actions from scientic Publishers and Journal Editors,in order to increase the awareness of the authors toward the scienticwriting best practice, the peer-review process and the Journals' wholepaper evaluation process. This presentation, by the Editor-in-Chief ofEJMP, indicates possible reasons for paper rejection, based on the pre-senter's experience as an author, as a reviewer, as Associate Editor and asEditor of a scientic Journal in medical physics. These reasons mayinclude lack of proper English writing, lack of motivations or originality,weaknesses in the methodological aspects or in the signicance of thendings and other specic reasons, which overall may indicate a generallack of convincing strength of the manuscript. Since publishing in a well-reputed scientic Journal is a competition for the acquisition of theconsensus in the Journal's audience, and hence in the correspondingscientic community, toward the work carried out in the specic study,lack of strength of a manuscript for one or more of the above reasons invariably leads to paper rejection. Ultimately, the efforts by the scienticcommunity toward reaching the best practice in scientic writing andevaluation, will hopefully produce a reduced Journals' rejection rate, andmost importantly, an improved efcacy of the research work, for thebenet of the scientic and social progess.

THE CURRENT STATUS OF MEDICAL PHYSICS RECOGNITION IN EUROPE

Stelios Christodes. Medical Physics Department, Nicosia General Hospital,Nicosia, Cyprus

The European Union recognises professions automatically if they meet therequirements of Directive 2005/36/EC [1], as this was amended by Direc-tive 2013/55/EU [2]. Automatic profession recognition gives the right ofprofessionals to move and work without any restrictions in any MemberState of the European Union.European recognition of the Medical Physics profession will allow Clini-cally Qualied Medical Physicists (CQMP) the same privileges as otherrecognised professions, such as Medical Doctors, Architects, Nurses, etc.Furthermore, Medical Physics Experts (MPE), as dened by Directive 2013/59/Euratom [3, 4], can have the same privileges, if are recognised by all theCompetent Authorities of all the Member States of the European Union.Currently, neither the CQMPs nor the MPs are recognised automatically asa profession by all the Member States of the European Union. The Euro-pean Federation of Organisations for Medical Physics (EFOMP) is workingfor many years in developing the education, training and competence ofMedical Physicists, both at the CQMP and MPE levels so as the

a Merequirements of the above Directives are met for automatic professionalrecognition.The purpose of this presentation is to give a brief account of the effortsmade by EFOMP and the requirements that need to be met, at the nationallevel, in order for both the CQMPs and MPEs can be automatically recog-nised by the European Union.References[1] Directive 2005/36/EC of the European Parliament and of the Council of7 September 2005 on the recognition of professional qualications, OJL255, 30.9.2005, pp 22-142.[2] Directive 2013/55/EU of the European Parliament and of the Council of20 November 2013 amending Directive 2005/36/EC on the recognition ofprofessional qualications and Regulation (EU) No 1024/2012 on admin-istrative cooperation through the InternalMarket Information System (theIMI Regulation), OJ L354, 28.12.2013, pp 132-170.[3] Council Directive 2013/59/Euratom of 5 December 2013 laying downbasic safety standards for protection against the dangers arising fromexposure to ionising radiation, and repealing Directives 89/618/Euratom,90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom,OJ L13, 17.1.2014, pp. 1-73.[4] European Commission, Radiation Protection Report 174, Guidelines onMedical Physics Expert, Directorate-General Energy, Luxembourg, 2014,available from: http://ec.europa.eu/energy/nuclear/radiation_protection/doc/publication/174.pdf (last accessed on the 11th of May 2014).

THE CURRENT STATUS OF MEDICAL PHYSICS RECOGNITION IN THEMIDDLE EAST

Ibrahim Duhaini. Chief Medical Physicist & RSO, Rak Hariri UniversityHospital, Beirut - Lebanon & President of the Middle East Federation ofOrganizations of Medical Physicists (MEFOMP), Lebanon

Medical physics is the branch of physics concerned with the application ofphysics to medicine, particularly in the diagnosis and treatment of humandiseases. From the time whenWilhelm Roentgen and other physicists madethe discoveries which led to the development of Diagnostic Radiology,Radiotherapy, Brachytherapy and Nuclear Medicine, Medical Physicistshave played a pivotal role in the development of new technologies thathave revolutionized the way medicine is practiced. In today's health carescene, the medical physicist is essential to the safe and cost effectiveoperation of any creditable medical institution.Medical Physics in the Middle East Region has passed in different stages. Inparticular the ISEP Conference held in Bahrain in November 2007 and the16 th ICMP Conference held in Dubai in 2008. During these conferences,there were several meetings for all the medical physics societies in theMiddle East. The result was the establishment in September 2009 of theMiddle East Federation of Organizations in Medical Physics (MEFOMP)which is part of the International Organization of Medical Physics IOMP.The following countries have signed up for this chapter: Bahrain, Iran, Iraq,Jordan, KSA, Lebanon, Oman, Qatar, Syria, UAE and Yemen. Ever since then,the medical physics profession has gone the rst mile in the road ofrecognition in most of the ME countries. Governmental entities and Uni-versity bodies started looking deeply into the need of promoting MP ac-tivities across the region.Now, Medical physicists in the ME region are considered scientists whothrough science are able to identify problems and unveil deciencies. It isalso through science that they solve the problems and correct the de-ciencies encountered in the diagnosis and treatment of diseases.There will be exciting and difcult challenges not only in the eld of healthcare but also in the race for nuclear power in the ME region. Countries willbe counting on the science of Medical Physics to help meet thesechallenges.Keywords: IOMP, MEFOMP, Middle East, Medical Physics, Recognition.

EDUCATION AND TRAINING OF MEDICAL PHYSICISTS IN EUROPE

V. Tsapaki. Konstantopoulio General Hospital, Athens, Greece

Background:Medical exposure represents the utmost and fastest growing

Abstracts / Physiccontribution to manmade radiation exposure not only in Europe but alsoacross the world. Furthermore, the evolution of medical equipment istherefore become part of an indispensable core team within the hospitalto ensure safe and procient use of medical equipment. His presence isgrowing alsowithin the industry and/or regulatory authority environment.In order to meet all these demands, sufcient education and training isindispensable. Collaboration and innovation in this eld is imperative forthe appropriate professional response to all these challenges. The Euro-pean Commission has for a number of years recognized the need foradequate theoretical and practical training of medical physicists for thepurpose of radiological practices. This is clearly stated in a number ofEuropean directives as well as in the latest European Basic Safety Stan-dards. A number of questions arise based on all these facts. Do we havesufcient number of adequately trained medical physicists or medicalphysics experts to address the needs of the increasing number of medicalprocedures in Europe? Is the education and training of such scientistsharmonized across Europe, that will facilitate in easier and mutualrecognition as well as improved cross-border mobility of medical physi-cists? The present paper will attempt to answer these questions using themost recent information within Europe.

EDUCATION AND TRAINING OF MEDICAL PHYSICISTS IN MIDDLE EASTKINGDOM OF BAHRAIN AS AN EXAMPLE

Lama Sakhnini. Department of Physics, College of Science, University ofBahrain, Sakhir, PO. Box 32038, Kingdom of Bahrain

Education: TheDepartment of Physics at University of Bahrain offers a B.Sc.in medical physics program. The program produces B.Sc. degree graduateswith a broad knowledge of fundamental and applied physics. With aspecialization in medical physics, the graduates will be eligible foremployment in hospitals, clinics, environmental establishments or indus-trial health care centers. Students should also be suitably prepared to carryout research in medical physics leading to a higher degree. The B.Sc. inMedical Physics degrees gives the opportunity to study the many medicalapplications of advanced physics.Medical physics courses, taught by staff ofthe department of Physics, are supplemented by specialist lectures given bysenior practicing medical physicists and doctors from Salmaniya medicalcomplex and Bahrain Defense force hospital. The B.Sc. programs inMedicalPhysics shares many common courses with the B.Sc. program in Physics,but nearly 48 credit hours include courses which are specic to MedicalPhysics program. A total of 42 female students graduated from the programso far, only 3 students managed to get jobs in the medical sector.Training: The B.Sc. in Medical Physics program ensures that the studentsgo through clinical training at hospitals in the Kingdom of Bahrain or in theKingdom of Saudi Arabia. In an ideal situation; the student spends aminimum of 2months of hospital training to complete a clinical rotation inradiation therapy, diagnostic imaging and nuclear medicine. The studentobserves and practices clinical procedures under the direct supervision ofa senior clinical medical physicist. The student is required to write aprogress report on the clinical procedures. However there is no welldesigned training program in the hospitals. Hence there is a disparate needfor a Residency Program which is aimed at both educating and providingpractical experience so that the medical physicist would be ready topractice in a hospital setting and obtain board certication. Training for ourstudents faced many challenges, as most hospitals do not have medicalphysicists, most hospital administrators do not know the rule of medicalphysicists, many hospitals have no quality management program and relyon the medical supplier of their equipment to do yearly maintenance.

EDUCATIONAL ACCREDITATION IN MEDICAL PHYSICS: IS ITIMPORTANT?

John Damilakis. Professor of Medical Physics, Greece

An increasing number of higher education institutions have in recent yearsstarted to offer courses on Medical Physics. Moreover, Continuing Profes-sional Development (CPD) for medical physicists is of great professionalcontinuous and fast, increasing the demand for high level scientists andexperts in the eld. To ensure that ionizing radiation is safely used, thepresence of the medical physicist is essential. The medical physicist has

dica 30S1 (2014) 7interest. CPD courses is an excellent way to ensure that Medical Physicists

Abstracts / Physica Medica 30S1 (2014)8become knowledgeable about all current issues in their eld and to pro-vide the necessary knowledge, skills and competences for certied Med-ical Physicists to become Medical Physics Experts. However, externalassessment of the quality of education or training provision is needed.Accreditation is the formal recognition that education and training onmedical physics provided by an institution meets acceptable levels ofquality. Accreditation should be based upon standards and guidelines.Requirements for accreditation of a training programme should take intoaccount several aspects including facilities, staff, educational material andteaching methods. In Europe, ENQA (European Network for QualityAssurance) promotes European co-operation in the eld of QualityAssurance in higher education. ENQA members are national agencies andorganizations, which play a major role in the accreditation process. A Eu-ropean organization is needed to offer accreditation of medical physicsCPD and training programs. Certication is the recognition of knowledge ofa professional who has completed his/her education or training. The EC hasdeveloped tools and frameworks to promote training and facilitatemobility. ECVET is a European system of accumulation and transfer ofcredits designed for vocational education and training in Europe.

IMAGE-GUIDED RADIATION THERAPY IN THE PRECLINICAL SETTING

Ross Berbeco PhD. Department of Radiation Oncology, Brigham andWomens Hospital, Dana-Farber Cancer Institute and Harvard MedicalSchool, USA

Current clinical radiation therapy is delivered with multiple collimatedbeams and accurate radiation dose calculation based on CT imaging.Additional advances in image-guided delivery techniques have saturated amajority of modern clinics. Therefore, modern translational research ofradiation biology and radiation physics using in vivo models of cancer re-quires a preclinical therapy platform that has the same capabilities asmodern clinical linear accelerators. In 2010, we established a preclinicalradiation biophysics laboratory at the Dana-Farber Cancer Institute andHarvardMedical School (Boston,MAUSA). The cornerstone of this facility isa Small Animal Radiation Research Platform (SARRP) which was developedby researchers at Johns Hopkins University (Baltimore, MD USA) andcommercialized by Xtrahl, Inc. (Surrey, UK). The SARRP combines a con-ventional x-ray tube with brass collimators to enable delivery of photonbeams as narrow as 0.5 mm at 220 kVp. Precise (sub-mm) image-guidedsetup is performed using cone-beam CT imaging combined with a roboticmotion stage. Absolute dose output is measured with an ADCL-traceableion chamber. Percentage depth-dose and beam proles are measured foreach collimator with EBT3 lm. Monte Carlo modeling of the SARRP isperformed using EGSnrc. The phase space les are used in a GPU-driven 3Ddose calculation engine with the 3D Slicer platform for visualization(Brigham andWomens Hospital Surgical Planning Laboratory, Boston, MAUSA). Collimator size, gantry and collimator angles, and target prescriptionare given and a 3D isodose distribution is calculated. Measurements inheterogeneousmedia have validated the dose calculation accuracy. Routinequality assurance procedures have been developed, based on thoseemployed for clinical radiation devices. The laboratory has facilities foranimal surgery, housing, anesthesia and injection. Our SARRP has beenoutttedwith a tube for continuous isourane delivery during imaging andtherapy procedures. To date,more than 1,000 preclinical procedures on liveanimals have been performed in the laboratory. Examples of currenttranslational research applications include genetic dependence of radiationresistance, chemical radiation sensitizers, metabolic modiers of radiationtherapy efcacy, metallic nanoparticles for enhanced radiation therapy andimaging contrast, and dermatologic studies. We anticipate that by utilizinga research instrument that provides accurate and precise radiation delivery,the results will have high translational relevance. Funding for these pro-jects has come from the United States Department of Defense, the NationalInstitutes of Health, philanthropic foundations and internal sources.

THE GEANT4-DNA PROJECT: OVERVIEW AND STATUS

Sebastien Incerti. CNRS, Bordeaux University, FranceOn behalf of the Geant4-DNA collaborationUnderstanding and prediction of adverse effects of ionizing radiation atthe cellular and sub-cellular scale remains a challenge of todays radiobi-ology research. In this context, a large experimental and modeling activityis currently taking place, aimed at better understanding the biologicaleffects of ionizing radiation at the sub-cellular scale. The Geant4-DNAproject was initiated by the European Space Agency [1]. It aims to developan experimentally validated simulation platform for the modeling of earlyDNA damage induced by ionizing radiation, using modern computing toolsand techniques. The platform is based on the general-purpose and open-source Geant4 Monte Carlo simulation toolkit, and benets from thetoolkits full transparency and free availability [2].This project proposes to develop specic functionalities in Geant4allowing:1) The modeling of elementary physical interactions between ionizingparticles and biological media, during the so-called physical stage.2) The modeling of the physico-chemical and chemical stages corre-sponding to the production, the diffusion and the chemical reactionsoccurring between chemical species. During the physico-chemical stage,the water molecules that have been excited and ionized during the physicsstage may de-excite and dissociate into initial water radiolysis products. Inthe chemical stage, these chemical species diffuse in the medium sur-rounding the DNA. They may eventually react among themselves or withthe DNA molecule.3) The introduction of detailed biological target geometry models, wherethe two above stages are combined with a geometrical description ofbiological targets (such as chromatin segments, cell nuclei). The Geant4-DNA physics processes and models are fully integrated into the Geant4toolkit and can be combined with Geant4 geometry modeling capabilities.In particular, it becomes possible to implement the geometry of biologicaltargets with a high resolution at the sub-micrometer scale and fully trackparticles within these geometries using the Geant4-DNA physics pro-cesses. These geometries represent a signicant improvement of thegeometrical models used so far for dosimetry studies with the Geant4toolkit at the biological cell scale.The current status of the project will be presented, as well as on-goingdevelopments.[1] S. Incerti et al., Comparison of Geant4 very low energy cross sectionmodels with experimental data inwater , Med. Phys. 37, 4692-4708 (2010)[2] S. Agostinelli et al., Geant4-a simulation toolkit, Nucl. Instrum.Methods. Phys. Res. A. 506, 250-303 (2003)

FIELD-CYCLING MRI: A NEW IMAGING MODALITY?

David J. Lurie, Lionel M. Broche, Gareth R. Davies, Nicholas Payne,Kerrin J. Pine, P. James Ross, Vasileios Zampetoulas. Aberdeen BiomedicalImaging Centre, University of Aberdeen, AB25 2ZD, Scotland, UK

Much of the contrast in conventional MRI arises from differences in theNMR relaxation times, especially the spin-lattice relaxation time, T-1. It isalso well known, from in vitromeasurements on small tissue samples, thatthe variation of T1 with the strength of the applied magnetic eld B0(known as T-1-dispersion) is tissue-dependent, and that the shape of atissues T-1-dispersion curve is altered in disease. However, T-1-dispersionis invisible to conventional MRI scanners, because each scanner can onlyoperate at its own native magnetic eld (e.g. 1.5 T, 3.0 T). The aim of ourwork is to exploit T-1-dispersion as a new MRI contrast mechanism, bybuilding new types of MRI scanner which make use of Fast Field-Cycling(FFC) [1].In FFC, the applied magnetic eld is switched rapidly, while the sample (orpatient) is inside the scanner. Thus, the nuclear magnetisation can bemadeto evolve at a range of magnetic eld strengths, allowing the measurementof T-1-dispersion. The magnetic eld is always switched to the same valueprior to measurement of the NMR signals, so that the instruments radi-ofrequency system does not require retuning during the procedure.In our laboratory we have built two whole-body human sized FFC-MRIscanners, one of whichmakes use of a dual magnet in order to achieve eldswitching [1,2]. The detection eld of 59 mT is provided by a vertical-eld,permanent magnet. Inside its bore is located a resistive magnet whichgenerates an opposing magnetic eld; eld-cycling is achieved by

switching the current in the resistive magnet coil.

A o ti he -to (C h it semission scan d ) o ta )

a MeWe have begun to explore bio-medical applications of FFC-MRI, and earlyresults have shown promise in the areas of thrombosis [3] and in osteo-arthritis [4], where the technique seems to be an indicator of early disease-related changes. FFC-MRI is showing signicant potential as a new variantof MRI. Please consult our web site (www.ffc-mri.org) for furtherinformation.[1] Lurie D.J., Aime S., et al., Comptes Rendus Physique 11, 136-148 (2010).[2] Lurie D.J., Foster M.A., et al., Phys.Med.Biol. 43, 1877-1886 (1998).[3] Broche L.M., Ismail S. et al., Magn.Reson.Med., 67, 1453e1457 (2012).[4] Broche L.M., Ashcroft G.P and Lurie D.J., Magn.Reson.Med. 68, 358-362(2012).

STANDARDS FOR MRT DOSIMETRY: THE METROMRT PROJECT

Vere Smyth a, Christophe Bobin b, Lena Johansson a, LeilaJoulaeizadeh c, Marco DArienzo d,e, Marco Capogni d, HansRabus f, Maurice Cox a, Jaroslav Solc g. aNational Physical Laboratory NPL,Hampton Road, Teddington, Middlesex, TW11 0LW, UK; bCommissariat alEnergie Atomique (CEA) Bt 476, Pt Courrier 142, CEA-Saclay, FR-91191 Gif-sur-Yvette Cedex, France; cVSL, Dutch Metrology Institute, Thijsseweg 11,P.O. Box 654, NL-2629, JA Delft, Netherlands; dNational Institute of IonizingRadiation Metrology, ENEA-INMRI, C.R. Casaccia, 00123 Rome, Italy;eDepartment of Human Anatomy, Histology, Forensic Medicine andOrthopedics, Sapienza University of Rome, Via Borelli 50, 00161 Rome,Italy; fPhysikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, D-38116 Braunschweig, Germany; gCzech Metrology Institute (CMI),Inspectorate for Ionising Radiation, Radiova 1, CZ-102 00 Prague 10,Czech Republic

The outcome for the patient of a molecular radiotherapy (MRT) procedureis determined by the radiation doses to the target tissue, and to criticalnormal tissue. It is well known that there is a wide variation betweenindividual patients in these doses for the same administered radiophar-maceutical activity. Generally a patient is given the maximum activity thatwill be tolerated by the normal tissue, on the basis of average populationstatistics obtained during clinical trials, in the hope that an effectivetreatment dose will be received. This practice could clearly be optimised ifthe respective doses could be determined for each patient, and the pre-scription based on this knowledge. Many clinical research centres aredeveloping dosimetry methods of increasing sophistication and accuracy,but to date these developments have very rarely had any effect on indi-vidual patient management. There are many reasons why this is so, but theobvious difference between MRT and other radiotherapy modalities is theabsence of a standard, internationally endorsed dosimetry protocol.Development of a dosimetry protocol analogous to the IAEA TRS398 pro-tocol (Absorbed dose determination in external beam radiotherapy, IAEA,Vienna, 2000) is difcult because of the complex nature of the steps in theMRT dosimetry process and dependence on the radiopharmaceutical be-ing used. However, difcult does not imply impossible. An internationalproject funded under the European Metrology Research Programme,MetroMRT (http://projects.npl.co.uk/metromrt/), is currently makingprogress in addressing this problem. The dosimetry process is analysedinto its component parts: activity measurement, quantitative imaging (QI),activity-time integration, and dose calculation, fromwhich ameasurementchain is constructed, traceable to primary radiation standards of radioac-tivity and absorbed dose, with an evaluated uncertainty. The greatestdifculties are relating a standard QI calibration to a measurement on apatient, and accounting for the uncertainty resulting from the combinationof different biokinetics, measurement time points, and integrationmethods in determining the uncertainty in the activity-time integrationstep. The MetroMRT project is in the nal year of its 3-year duration. De-tails of the individual tasks and success achieved so far will be presented.

RADIOPHARMACEUTICAL DOSIMETRY: FROM THE ANIMALS TO THECLINICS

Manuel Bardies. UMR 1037 INSERM/UPS, Centre de Recherche enCancerologie de Toulouse, Toulouse, France

Abstracts / PhysicNuclear Medicine dosimetry is not limited to the clinical scale (i.e. organ ortumor).that in clinical practice can be selected by the user, or object properties(such as target dimensions, target-to-background (T/B) ratio and activityoutside the eld of view) which depends uniquely on the intrinsic char-acteristics of the object being imaged.Methods and Results: In the rst experiment CNR was studied as afunction of ESD and Aacq for different target sizes and T/B ratios using amultivariate approach in a wide range of conditions approaching the onesthat can be encountered in clinical practice. Sequential imaging was per-formed to acquire PET images with varying background activity concen-trations of about 12, 9, 6.4, 5.3 and 3.1 kBq/mL. The ESD was set to 1, 2, 3,and 4 min/bed. The ESD resulted as the most signicant predictor of CNRvariance, followed by T/B ratio and the cross sectional area of the givensphere. Only last comes Aacq with a weight halved with respect to ESD.Thus, raising ESD seems to be much more effective than raising Aacq inorder to obtain higher CNR.In the second experiment a scatter phantom was positioned at the end ofthe modied IEC phantom to simulate an activity that extends beyond thescanner. The modied IEC phantomwas lled with 18F (11 kBq/mL) and thespherical targets had a target-to-background ratio of 10. PET images wereacquired with background activity concentrations into the FOV (Ac,bkg)about 11, 9.2, 6.6, 5.2 and 3.5 kBq/mL. ESD was set to 1, 2, 3, and 4 min. Thetube inside the scatter phantom was lled with activities to provide anAc,out in the whole scatter phantom of zero, half, unity, twofold and four-fold the one of the modied IEC phantom. CNR diminishes signicantlywith increasing outside FOV activity, in the range explored. ESD and Ac,outhave a similar weight in accounting for CNR variance. A recovery of CNR

loin

ss due to an eindividual beuration (ESDlevated Ac,out actd positions accor activity at the sivity seems feasiblerding to the Ac,out.rt of acquisition (Aacq)

-noise ratio NR)) behavew en varying acquis ion parameters (such a

im: The aim f this presenta on is to describe t way inwhich contrastPreclinical studies, involving animal (or cell experiments) also can benetfrom sound dosimetric studies. Small animal studies are required duringthe development of new radiopharmaceuticals (diagnostics or therapy).The general relevance of radiopharmaceutical dosimetry applies equally topreclinical and clinical studies. The MIRD scheme can most often beapplied, even at the cellular level, as long as macrodosimetric parameters(mean absorbed doses) remain relevant.However, there are differences in the goals and in the methodologyrequired to perform studies:For diagnostic tracers, during the development phase, small-animalradiopharmaceutical biodistribution and pharmacokinetics are frequentlyextrapolated to humans. However, absorbed dose delivered are usually notconsidered.For therapeutic nuclear medicine, absorbed doses are computed to docu-ment the biological effect observed (efcacy/therapy), and that can beperformed in a preclinical context. As for clinical dosimetry, the issue ofmodel versus specic dosimetry must be addressed. Cumulated activity is most often determined from organ/tissues activitymeasurements at different time points, from ex vivo counting. Absorbed dose calculation can be carried out with more or less sophis-ticated radiation transport codes.The table below presents the variouspossibilities offered to perform nuclear medicine dosimetry at the clinicalscale. How that table can be extrapolated in a context of preclinicaldosimetry will be discussed.

Context Cumulatedactivity (Bq.s)

S values(Gy.Bq-1.s-1)

Absorbeddose (Gy)

Diagnostics Model Model Model-basedTherapy Specic Model adjusted Model-based realisticTherapy Specic Specic Specic

Within multidisciplinary teams involved in radiopharmaceutical research, physi-cists should not only focus on the clinical aspects but also participate to preclinicalstudies.

ACQUISITION PROTOCOLS FOR 18F-FDG WHOLE BODY PET/CT:OPTIMIZING SCAN DURATION VERSUS ADMINISTERED DOSE

Marco Brambilla. Medical Physics Department, University Hospital OfNovara, Novara, Italy

dica 30S1 (2014) 9bymodulating the ESD

MeConclusions: The European Association of Nuclear Medicine procedureguidelines for whole-body FDG-PET scanning still prescribe a dose pro-portional to the patients body mass. However, clinical practice andexperimental evidences show that using an FDG dose proportional to bodymass does not overcome size-related degradation of the image quality anddifferent algorithms should be devised instead.

NEW ANALYTICAL ALGORITHMS FOR PET AND SPECT

George Kastis. Academy of Athens, Medical & Biological Research Foundation(IIBEAA), Athens, Greece

Positron emission tomography (PET) and single-photon emissioncomputed tomography (SPECT) are the most important nuclear medicineimaging modalities that measure the in vivo distribution of imagingagents labeled with emitting radionuclides. Image reconstruction is anessential component of both modalities, allowing tomographic images tobe obtained from a set of two-dimensional of three-dimensional projec-tion data. The existing image reconstruction methods can be classiedinto two main categories: analytical methods and iterative (or statistical)methods.Filtered backprojection (FBP) is the predominant analytic reconstructionmethod. Its mathematical formulation is based on the inversion of theRadon transform through the central slice theorem. The main advantagesof FBP are speed and simplicity. However, in FBP it is difcult to incorporatecomplex physical phenomena such as attenuation and scatter. The pre-dominant iterative algorithms are the maximum-likelihood expectation-maximization (MLEM) algorithm and its accelerated successor the or-dered-subsets expectation-maximization (OSEM) algorithm. The mainadvantage of the iterative algorithms is the ability to model several aspectsof the imaging system, including elements of the noise characteristics,sinogram blurring due to detector crystal penetration, depth of interaction,photon scatter, and attenuation in the body. As a consequence, iterativemethods can improve image quality and achieve considerable resolutionrecovery. However, iterative algorithms require more computing time andpower. Furthermore, there is the challenge of choosing the right number ofsubsets and iterations which leads to a tradeoff between noise and bias.Although iterative methods are now in widespread use in clinical andpreclinical systems, recent studies have concluded that analytical methodscould still have advantages over analytic methods in specic applications.For example, a recent dynamic brain PET study by Reilhac et al. concludedthat analytical methods are more robust to low count data than iterativemethods. In another study by Conti et al., it was demonstrated that TOF FBPhas improved performance over TOF OSEM.In this presentation we will present recent results from the spline recon-struction technique (SRT), a new analytic, two-dimensional reconstructionalgorithm based on cubic splines. We will present the mathematicalformulation of the algorithm and comparisons with FBP and OSEM, usingsimulated data from a clinical PET system, as well as real data obtainedfrom clinical and preclinical PET scanners. Furthermore, we will presentpreliminary results from IART (inverse attenuated Radon transform), ananalytic reconstruction technique based on cubic splines that inverts theattenuated Radon transform and is better suited for SPECT where atten-uation correction is needed.

AN OVERVIEW OF THE CONCERT PROJECT

John Damilakis. Professor of Medical Physics, University of Crete, Greece

The overall aim of the CONCERT (Conceptus Radiation Doses and Risksfrom Imaging with Ionizing Radiation) project is to perform originalresearch fromwhich new ndings, innovations and practical guidelines foroptimal clinical management of pregnant patients needing radiologicprocedures will result. An additional objective is to generate dose data thatmay be used for the implementation of a radiation protection programdesigned for pregnant employees working in imaging departments,interventional laboratories and electrophysiological suites.The activities of the project focus on the following main tasks:a) Conduction of a nation-wide study (survey) on current practice patterns

Abstracts / Physica10in imaging of pregnant patients and on policies for screening women ofchildbearing age for pregnancy before imaging with ionizing radiationb) Development of methods for estimation of conceptus dose from imag-ing examinations performed on the motherc) Development of a method for (a) anticipation of conceptus dosefrom occupational exposure of pregnant staff during uoroscopically-guided procedures and (b) estimation of maximum workloadallowed for each month of gestation period following pregnancydeclarationd) Development of a software expert system that will allow a) calculationof conceptus radiation dose and risk associatedwith imaging examinationsperformed on the expectant mother and (b) anticipation of conceptusdose and determination of the maximum workload for the pregnantemployee who participates in uoroscopically-guided interventionalprocedurese) Organization of a workshop on pregnancy and radiation protection todiscuss the ndings of the survey and disseminate the research results.f) Development of guidance document on a) the management of pregnantpatients who need radiologic examinations, b) the management of preg-nant employees exposed to considerable levels of occupational radiationand c) policies for screening women of childbearing age for pregnancybefore imaging proceduresThe project started in September 2012 and ends in September 2015.CONCERT is supported by the Greek Ministry of Education and ReligiousAffairs, General Secretariat for Research and Technology, OperationalProgram 'Education and Lifelong Learning', ARISTIA.

HOW TO ESTIMATE CONCEPTUS RADIATION DOSE FROMRADIOGRAPHIC, FLUOROSCOPIC AND FLUOROSCOPICALLY GUIDEDINTERVENTIONAL PROCEDURES? (REVIEW COURSE TALK FOR THECONCERT PROJECT)

G. Solomou, J. Stratakis, J. Damilakis. Department of Medical Physics,Faculty of Medicine, PO Box 2208, University of Crete, Iraklion 71003,Crete, Greece

Radiologic evaluation may be needed during pregnancy to assess commoncauses of acute abdominal or thoracic pain. Accidental irradiation ofpregnant women from radiologic examinations may occur during theearly postconception weeks. In each case, there has been a growingconcern about radiation exposure which invokes a great anxiety for thepregnant patient as well as the treating doctor and may probably lead tothe unnecessary termination of pregnancy. However, conceptus dosesbelow 100 mGy should not be considered a reason for termination. Whilesuch a high-level exposure rarely occurs during a single medical diag-nostic procedure, the estimation of conceptus radiation dose is essentialto determine radiogenic risks to the unborn child and inform theoncoming mother.Several methods have been developed to estimate conceptus radiationdose in pregnant woman who undergo radiographic, uoroscopic anduoroscopically guided interventional procedures. These methods usethermoluminescence dosimeters along with anthropomorphic phantoms,which represent pregnant patients at various gestational stages. Compu-tational methods, which are based on the Monte Carlo transportation codeas well as mathematical phantoms have also been applied to estimateconceptus radiation dose in radiologic procedures. An advantage of thelatter methods is that they may take into account the somatometriccharacteristic of the pregnant patients, such as body size, perimeter of theabdomen and conceptus location.A literature review on the methodologies applied to estimate conceptusradiation dose in pregnant patient who undergo diagnostic radiologicalprocedures is presented.

HOW TO ESTIMATE CONCEPTUS DOSE FROM CT EXAMINATIONS

Kostas Perisinakis. Department of Medical Physics, Faculty of Medicine, POBox 2208, University of Crete, Iraklion 71003, Crete, Greece

The utilization of computed tomography (CT) in pregnant patients hasincreased in recent years, following the same trend observed for non-pregnant patients. In case of a pregnant patient subjected to CT exposure,

dica 30S1 (2014)apart from the risk for carcinogenesis to the expecting mother, there is alsoconcern about the teratogenic and carcinogenic effects of ionizing

Abstracts / Physica Medica 30S1 (2014) 11radiation to the developing conceptus. To estimate the radiogenic risks foran exposed conceptus to be used in risk benet analysis for a certain CTexamination, the accurate determination of absorbed dose to theconceptus is prerequisite.CT exposures of pregnant patients may be categorized in three typescorresponding to conceptus a) entirely excluded, b) partially includedand c) entirely included in the primarily exposed body region. Thiscategorization is associated with the size of conceptus at the time ofexposure. As gestation progresses, conceptus size is increased andtherefore, partial conceptus exposures may occur with increasedpossibility.Several methods have been proposed in literature for the determinationof conceptus dose from CT exposures such as a) the use of the computedtomography CT dose index (CTDI), b) the IMPACT CT Patient DosimetryCalculator, c) formulas and relevant data provided in the literature, d)Monte Carlo simulation with standard anthropomorphic mathematicalphantoms simulating pregnant patients at different gestational stagesand e) the IMPACT MC dosimetry tool. Some methods are limited to the1st trimester of pregnancy while others may be used in all gestationalstages. Some methods may be used only in case of entire or partial directexposure of conceptus while others may be also used in case conceptusis not primarily exposed. Applicability of the above methods in associ-ation with z-overscanning effect and the use of adaptive section colli-mation, the use of automatic exposure control and the use of iterativereconstruction algorithms will also be discussed. The pros and cons ofthe above methods regarding accuracy, applicability, required equip-ment and cost will be discussed and guidelines will be providedregarding the appropriate use of available methods to estimateconceptus dose in case of intentional or inadvertent CT exposure of apregnant patient.

OCCUPATIONAL EXPOSURE OF PREGNANT PERSONNEL (REVIEWCOURSE TALK FOR THE CONCERT PROJECT)

John Stratakis PhD, Kostas Perisinakis PhD, Georgia Solomou MSc, JohnDamilakis PhD *. Department of Medical Physics, Faculty of Medicine, POBox 2208, University of Crete, Iraklion 71003, Crete, Greece

Development of interventional radiology (IR) has been accompanied by asignicant concern for the safety of the staff involved in interventionalprocedures, since patient and staff doses in the IR laboratory may beincreased because of case difculty, patient condition, and operatorsexperience. Many researchers have pointed out issues of interest withinthe optimization of radiation protection that included assessment of doseand risks of interventional laboratory personnel focused mainly on radi-ation protection on cardiological, orthopedic and angiographic procedures.Information about conceptus occupational exposure during IR proceduresstill remains limited.An anthropomorphic phantomwas exposed at projections commonly usedin IR procedures. An extended range of combinations of tube voltage andbeam ltration were used. For the measurement of scattered air-kerma,the area relative to the sides