S 48 SYMPOSIUM TUESDAY, SEPTEMBER 1, 2009

SymposiumTreatment planning, tumour sites128 speaker

GENERAL: THE ADVANCED ROLE OF THE RTT IN TREATMENTPLANNINGS. Simpson1

1 CLATTERBRIDGE CENTRE FOR ONCOLOGY, Radiation Oncology, Bebing-ton, Merseyside, United Kingdom

Therapeutic Radiographers within the UK are recognised members of themultiprofessional team in pre-treatment and dosimetry working at levels frompractitioner to consultant level, across a number of radiotherapy centres withinthe UK. In the UK Therapeutic radiographers have core skills at registration indosimetric planning and with the addition of post registration education andtraining highly skilled radiographers, working at higher levels of practice arenow responsible for outlining both normal and target treatment volumes andfor undertaking IMRT planning in some centres, under locally agreed proto-cols of care. This role development has the potential to streamline patientcare whilst making best use of the available workforce to ensure new treat-ment techniques and waiting time targets are met for all patients in the UK.This change to skills mix from the traditional model reliant upon the clinicaloncologist is providing opportunity for career progression for radiographersand ensures all their core skills and knowledge of the radiotherapy treatmentpathway are utilised for the benefit of the service.

129 speaker

ESCALATED DOSE FOR NON-SMALL-CELL LUNG CANCER WITHACCELERATED HYPOFRACTIONATED THREE-DIMENSIONALCONFORMAL RADIATION THERAPYP. Thirion1, S. Brennan1, D. Fitzpatrick1, J. Armstrong2, M. Dunne3, C.O’Shea3, A. McElroy31 ST LUKE’S HOSPITAL, Department of Radiation Oncology, Dublin, IrelandRepublic of2 ST. LUKE’S HOSPITAL, Department of Radiation Oncology, Dublin, IrelandRepublic of3 ST LUKE’S HOSPITAL, Clinical Trials Unit, Dublin, Ireland Republic of

Purpose/Objective: Radiotherapy intensification by combining dose esca-lation and acceleration may improve local control in Non-Small-Cell LungCancer (NSCLC) but has a potential for significant toxicity. An institutionalphase I/II trial (ICORG 99-09) was conducted to evaluate the safety and ef-ficacy of an accelerated hypofractionated schedule using free-breathing 3-Dimensional Conformal Radiation Therapy (3-DCRT), omission of electivenodal irradiation and application of strict dose-volume-constraints (DVC).Material/Methods: 46 patients (pts) with stage I-III medically inoperable/ non-resectable NSCLC, weight loss less ≤ 10% and KPS ≥70% weretreated with 3-DCRT delivering a radiation schedule of 72 Gy in 24 daily frac-tions, 5 fractions/week, over 32 days. The DVC were maximum dose to spinalcord < 62% and combined lung V25Gy ≤ 30%. Median age was 65 years(Range: 45-87) and 35 pts were male. Tumour stage was respectively I in10 pts, II in 3 pts and III in 33 pts, and tumour was centrally located in 44pts. 26 pts had induction chemotherapy. Primary endpoints were acute andlate pulmonary (SWOG scale) and every other organs (RTOG/EORTC scale)toxicity. Secondary endpoints were response rate at 3 months (mths), time totumour progression (TTP), time to tumour local progression (TTLP), time todistant progression (TTDP), progression free survival (PFS) and overall sur-vival (OS).Results: The main acute toxicities were pulmonary [26 pts: Grade (Gr)1 =23 pts, Gr2 = 3 pts] and oesophageal [36 pts: Gr1 = 28pts, Gr2 = 5 pts, Gr3 =3 pts] with one 4-day treatment interruption. With a median follow-up (f/u) of24.2 mths [Range 6.9-75.5], 10 pts developed late pneumonitis [Gr1 = 9 pts,Gr3 = 1 pts]. Following two reported Gr 5 late oesophageal toxicity events(Thirion, ASCO 2004) an additional oesophageal DVC [98% isodose circum-ferential oesophagus ≤1 cm] was introduced. Since then 10 pts [median f/u=14.9 mths] were treated with no Gr5 toxicity and Gr1 = 1pt, Gr2 = 1pt, Gr3= 1pt. Tumour response rate at 3 mths were: CR: 17.4%, PR: 32.6% , SD:19.6% and PD: 23.9% [Non-evaluable: 6.5 %]. The other results for efficacywere: median TTP = 15.2 mths, median TTLP =12.6 mths, median TTDP =10.9 mths and median OS=17.9 mths [1 yr OS=78%, 3 yr OS=26%].Conclusions: The studied accelerated hypofractionated regime is feasible,with late oesophageal toxicity being the dose-limiting toxicity. The proposedoesophageal DVC is under prospective evaluation. The median survival andTTLP results are encouraging as 70% pts had Stage III disease.

130 speaker

THE TREATMENT AND 3D VERIFICATION OF AN INVERSEPLANNED IMRT FOR THE WHOLE CENTRAL NERVOUS SYSTEMJ. Davies1, J. Stratford1, M. Duffy1, H. Pennington1, P. Whitehurst2, C.Rowbottom2, R. I. Mackay2, H. Gattamaneni31 CHRISTIE HOSPITAL NHS FOUNDATION TRUST, Wade Centre forRadiotherapy Research, Manchester, United Kingdom2 CHRISTIE HOSPITAL NHS FOUNDATION TRUST, North West MedicalPhysics, Manchester, United Kingdom3 CHRISTIE HOSPITAL NHS FOUNDATION TRUST, Manchester, UnitedKingdom

Purpose: The clinical introduction, treatment and verification of an inverseplanned Intensity Modulated treatment for the whole Central Nervous System(CNS). This new technique incorporated the previously used supine patientpositioning whilst offering the advantages of superior planning and deliverytechniques. Improvements included uniformity and conformity of the PTV, theuse of one standard plan throughout the whole of the treatment, negating theneed for multiple moving centre’s, hence less open to operator error. Thetechnique improved the speed of delivery and introduced 3 dimensional veri-fication using cone beam.Materials: To date four patients have been treated using this new techniqueon an Elekta Synergy 6MV linear accelerator. The whole CNS receives 35Gy in 20 fractions and is inversely planned with a sequential cranial boost de-livering 20 Gy in 10 fractions. Cone beam is used to verify positioning usingan offline NAL protocol, patient’s imaged fractions one to three and weeklythereafter with a tolerance of 3mm for cranial fields and 5mm on the spinalfields. Additional imaging was instigated as required if tolerances were ex-ceeded.Results: The use of cone beam imaging has allowed increased visualizationand quantification of positioning including rotations within the spinal axis andcranium. Cranial displacements on all patients and all images were within the3mm tolerance. For each individual patient the average spinal discrepancieswere within the 5mm tolerance. Random variation in spinal positioning wasidentified predominantly in the lumbar region. This variation did not affectdosimetry or compromise the target volume.Conclusion: The demands of service has led to improved planning, deliv-ery and verification of CNS patients. The requirement of multiple plans cre-ating staggered junctions has been replaced by a simplified one plan ap-proach which has improved workflow within this institution. 3D verificationand improved image quality has confirmed that treatment can be deliveredaccurately within departmental tolerances.Early indications infer the marginscurrently used for cranium and spinal fields could be safely reduced.

131 speaker

RAPIDARC COMPARED TO IMRT FOR H&N CANCERE. Vanetti de Palma1, A. Clivio1, G. Nicolini1, A. Fogliata Cozzi1, S.

Ghosh-Laskar2, J. P. Agarwal2, R. R. Upreti2, A. Budrukkar2, V. Murthy2, D.Deshpande2, S. K. Shrivastava2, K. Dinshaw2, L. Cozzi11 IOSI, Bellinzona, Switzerland2 TATA MEMORIAL HOSPITAL, Mumbai, India

Purpose: The aim of the present study was to investigate the potential clin-ical role for head and neck cancer patients of RapidArc, the novel radiationtreatment technique (Varian Medical Systems), which is based on volumetricintensity-modulated arc delivery, as opposed to intensity modulation whichuses fixed gantry beams.RapidArc aims to (i) improve OARs and healthy tis-sue sparing compared to other solutions; (ii) maintain or improve the samedegree of target coverage; and (iii) reduce beam-on time per fraction.Methods and materials: CT datasets of 29 patients with squamous cell car-cinoma of the oro-pharynx, hypo-pharynx and larynx were included. Plansfor fixed beam IMRT, single (RA1) and double (RA2) modulated arcs with theRapidArc technique were optimised. Dose prescription was set to 66 Gy tothe primary tumour (at 2.2 Gy/fraction), 60 Gy to intermediate-risk nodes and54 Gy to low-risk nodal levels.The planning objectives for PTV were minimumdose >95%, and maximum dose <107%. Maximum dose to spinal cord waslimited to 46 Gy, maximum to brain stem to 50 Gy. For parotids, mean dose<26 Gy (or median <30 Gy) was assumed as the objective. The MU and de-livery time were scored to measure expected treatment efficiency.Results: Target coverage and homogeneity results improved with RA2 planscompared to both RA1 and IMRT. All the techniques fulfilled the objectiveson maximum dose, while small deviations were observed on minimum dosefor PTV. The conformity index (CI95%) was 1.7 ± 0.2 for all the three tech-niques. RA2 allowed a reduction of D2% to spinal cord of ~3 Gy comparedto IMRT (RA1 D2% increased it of ~1 Gy). On brain stem, D2% was reducedfrom 12 Gy (RA1 vs. IMRT) to 13.5 Gy (RA2 vs. IMRT). The mean dose toipsi-lateral parotids was reduced from 40 Gy (IMRT) to 36.2 Gy (RA1) and34.4 Gy (RA2). The mean dose to the contra-lateral gland ranged from 32.6Gy (IMRT) to 30.9 Gy (RA1) and 28.2 Gy (RA2).Conclusion: RapidArc was investigated for head and neck cancer. RA1 andRA2 showed some improvements in organs at risk and healthy tissue sparing,while only RA2 offered improved target coverage with respect to conventional