The University of Texas

M.D. Anderson Cancer Center

Current Status of Proton Clinical Activities at PTC HMichael Gillin, PhD, Professor, Chief of Clinical Services

Department of Radiation Physics, UT MDACC

M.D. Anderson Cancer Center

Proton Therapy Center

New Old

UT MDACC Radiation OncologyUT MDACC > 24,000 patients/year

• > 7,000 patients per year treated in Radiation Oncology• Main campus (20 linacs)• PTC H• 4 Regional Care Centers in greater Houston area• Albuquerque, New Mexico• Albuquerque, New Mexico• Istanbul, Turkey• > 60 radiation oncologists• Filmless, paperless practice. With the exception of

Istanbul, all sites, including PTC H, use the same EMR, Mosaiq V 1.6.

• Photon TPS Pinnacle, Proton TPS Eclipse

140 MeV Protons and 50 MeV Electrons (U of Michigan)

140 MeV proton PDD vs 50 Mev Electron PDD

80.00

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Proton 140 MeV 8 cm SOBP

Proton 140 MeV 10 cm SOBP

Electron 50 MeV

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Protons: Flat peak, sharp drop off. Range controlled to within 1 mm in water. What clinical sites benefit from these characteristics?

Why protons? It is a positive experience.

PTC HBrief History

• Acceptance testing team did the AT.• Clinical physics was responsible for

commissioning and continuous support, beginning March, 2006.

• First patient with scattered beam, May, 2006• First patient with scattered beam, May, 2006• First patient with scanned beam, May, 2008• 2,600 patients treated with protons (March 2011)

– 1250 GU patients, > 400 pediatric patients, > 400 thoracic patients

– > 400 scanned beam patients (SFO and SFIB), > 10 MFO

Patient Daily Census and ECA (June 2007 – March 2011)

ECA = [(FST-EDT)/FST] X 100 ECA: Equipment Clinical Availability

FST: Facility Schedule Time; EDT: Equipment Down Time

ECA

5

Patients

Major Systems for Protons• CT scanners: GE at PTC and GE and Philips on

main campus CT number/stopping power • Hitachi Treatment Delivery PROBEAT• Hitachi imaging systems and Hitachi PIAS

(Patient Image Analysis System)(Patient Image Analysis System)

• Varian Eclipse Planning, V 8.9• Anderson MU Determination for scattered beam• IMPAC EMR Mosaiq V1.6 supports scattering

and scanning – All patients have been treated using the EMR.

• Gibbscam for aperture and compensator construction on Mazak milling machines.

Major Challenges for Protons

• Treatment Planning System – TPS have been a major challenge, as they are quite immature. In June, 2011 we will have migrated to our fourth major version of TPS.

• Competing demands to treat patients, improving • Competing demands to treat patients, improving treatment techniques and program development.

• Digital communication between various vendors:TPS to EMR through MDACC filter to Rx Delivery to EMR

Clinical physicists want to measure everything, but time is limited.

Proton Therapy Center - Houston

Passive Scattering Port

Pencil Beam Scanning Port

Experimental Port

PTC-H3 Rotating Gantries1 Fixed Port1 Eye Port1 Experimental Port

Large Fixed Port Eye Port

Experimental Port

Accelerator System(slow cycle synchrotron)

Treatment Mode

Physics Mode

Service Mode

PTC H Operations, April, 2011

• 110 to 130 patients per day, treated from 6 AM to 11 PM, Monday through Friday

• Morning QA < 30 minutes per beamline• Saturday Physics time 8 AM until 8 PM• Saturday night and Sunday Hitachi • Saturday night and Sunday Hitachi

maintenance.• 96 to 97% uptime. Most troublesome

component has been the 7 MeV linac.• Highly controlled environment: ~ All changes

are reviewed by MDACC and Hitachi before they are made.

Selected PTC H Staff

• 8 clinical physicists (2 shifts), 1 accelerator physicist –faculty physicists are expected to work on an every other Saturday basis. TPS requires ~ 1.5 FTE clinical physics effort

• 2 Clinical Physics Fellows• 4 Physics Assistants (2 ea AM, 2 ea PM)• 4 Physics Assistants (2 ea AM, 2 ea PM)• 4 machinists for compensators and apertures• 3 MDACC service techs + 5 Hitachi service techs + 2

Hitachi management• 15+ oncologists who regularly treat patients• ~ 16 RTTs – two shifts• 9 clinical dosimetrists, 2 research dosimetrists• IT support, administrative support, bureaucrats, etc.

2 Stage Linear AcceleratorCurrently 20 Hz, soon 2 HzAccSys – Made in California

Duoplasmatron

Max. 30 Hz

Ion Source

RFQ DTLEinzel lens

Synchrotron Accelerator

Circumferential

Length: 23 meters

Extraction

Energy: 70 to 250 MeV

Energy Extraction Scheme Energy resolution:

0.4 MeV

Design value of the extracted particles: 0.75 x 1011 ppp at 250 MeV

Extraction Scheme

Transverse RF driven with Separatrix Constant Extraction

Accumulated Charge in the Synchrotron

• This may be the most important parameter for delivering beam to both the passive and scanning nozzles. The accumulated charge should be ~ 15 nC for all energies for passive scattering and ~ 5 nC for higher energies and ~ 3 nC for lower energies for scanned beam.

• Operating parameters which control this include the • Operating parameters which control this include the voltage and position of the Electro Static Inflector, which changes the injection condition in the synchrotron and the relative phase of the debuncher, which adjusts the energy and energy distribution of the 7 MeV protons in the linac.

• The ESI and the debuncher are tuned manually on an as needed basis.

PTC H SynchrotronPassive Scattering

• Passive scattering: Beam on 0.5 seconds, Beam off 1.5 seconds, low dose rates – 75 to 200 cGy/min

• 3 snouts: large (25 cm x 25 cm), medium (18 cm x 18 cm), and small (10 cm x 10 cm)

• 8 Energies (250, 225, 200, 180, 160, 140, 120, and 100 MeV)• A separate RMW for each snout and energy – SOBP width from 2

cm to 16 cm.• Range shifters to adjust depth to within 1 mm.• Snout is adjustable from isocenter to 45 cm from isocenter.

G2_250MeV_RMW91_range28.5cm_mediumsnout@5cm

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Depth (mm)

PD

D SOBP 4 cm, Measured 4.2 cmSOBP 10 cm, Measure 10.2 cmSOBP 16 cm, Measured 16.1cmSOBP 12 cm, Measured 12.0 cmSOBP 8 cm, Measured 8.1 cmSOBP 6 cm, Measured 6.1 cmSOBP 14 cm, Measured 14.3 cm

G2_250MeV_RMW88_range25.0 cm_largeSnout@5cm

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Depth (mm)

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D

SOBP 4 cm, Measured 3.9 cmSOBP 6 cm, Measured 5.9 cmSOBP 8 cm, Measured 7.9 cmSOBP 10 cm, Measured 10.0 cmSOBP 12 cm, Measured 12.2 cmSOBP 14 cm, Measured 14.3 cmSOBP 16 cm, Measured 16.6 cm

G2_160MeV_RMW76_range13.0cm_mediumsnout@5cm

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Depth (mm)

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D SOBP 10 cm, Measured 10.6 cmSOBP 8 cm, Measured 8.2 cmSOBP 6 cm, Measured 6.1 cmSOBP 4 cm, Measured 4.0 cm

G2_160MeV_RMW4_range 11.0 cm_large Snout at 5 cm

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D SOBP 4 cm, Measured 3.8 cm

SOBP 6 cm, Measured 5.8 cm

SOBP 8 cm, Measured 7.8 cm

SOBP 10 cm

PTC H Proton BeamsScattered Scanned

• Ranges: 1 mm to 324 mm in 1 mm increments using range shifters

• 100 to 250 MeV• 8 Energies• Maximum Field Size: 10x10,

18x18, 25x25 cm2

• Pulse length: 0.5 sec

• Ranges: 40 mm to 306 mm in 1 mm to 6 mm increments

• 72.5 to 221.8 MeV• 94 energies• Maximum Field Size: 30 x 30 cm2

• Maximum pulse length: 4.1 sec• Pulse length: 0.5 sec• Time between pulses: 1.5 sec• Apertures and compensators

• 24 different scattering conditions per beamline

• TPS does not provide MUs, because MDACC did not take the time to implement it.

• Maximum pulse length: 4.1 sec• Time between pulses: 2.1 sec

• TPS, at this point in time, does not support apertures.

• Soon Energy Absorbers, as a new version of TPS is released.

• TPS provides MUs, as it is required. Per spot, MUs range from 0.005 to 0.04.

PTC H Machine QAScattered Beam

• System works. 99.999% of patients are started on time. EMR is used for 100% of patients.

• 24 hours are required to make apertures and compensators. This has been incorporated into normal clinical workflow.

• Proton production shop: 5+ days/week• Proton production shop: 5+ days/week• Physics in-room activities: Saturdays and late at night

and 5:30 AM morning QA• Annual machine QA – very time consuming – 40 to 100

hours on Saturdays. G1 16 different beams, G2 24 different beams, F2 3 different beams. There are annual reviews going on all year long.

Patient Specific QA5 cm/10 cm water box

Which is designed to hold a Farmer type chamber. We also use a Markus or a pinpoint chamber.

Solid water plates to obtain the desired depths.

Note brass apertures and no compensator

The Physics Miracle transforming treatment plans into treatment delivery parameters, including MUs. Generally physics spends 1 to 2 hours after planning is finished to review and prepare for treatment. 27 field cranial spinal patients may require 8 to 10 hours.

PTC H Patient QAScattered Beam – All MUs are

based upon measurements• 1 – 8 hours Physics plan review including

images• 0.5 hr Verification plan creation• 0.5 hr MU determination• 0.5 hr MU determination• 0.1 hr Aperture/compensator QA• 0.1 hr Physical collision check• 0.2 hr EMR sign off• 2 to 10* hours Total physics time per patient• * Cranial spinal patients require substantial

physics time

Cranial spinalpatient supine

~15 to 20 cranial spinal patients are treated per year. Each new field requires new apertures. Spinal fields change each week.

Machine QA Scattered Beam - DailyICRU 78 PTC H Practice

• Interlocks/Communication• Room lasers• Aperture alignment• Pt positioning system• Depth dose and lateral profiles

• Interlocks/Communication• N/A – lasers not used• First Rx aperture film• Couch movement• 1 energy, 3 points, review

output from segmented

• Dose monitor cal

• Individual patient treatment calibration and range checks

output from segmented chamber – measured field size

• Dose vs. MU – standard condition

• Part of patient QA, but not range checks

• Data flow from EMR to RX delivery and imaging systems

• X-ray system alignment

Machine QA Scattered Beam - WeeklyICRU 78 PTC H Practice

• Patient position and imaging systems

• Beam line apparatus

• Imaging systems –daily check of x-ray/proton alignment.

• ? What apparatus• Beam line apparatus• Respiratory gating

• Dose delivered to randomly selected patients

• ? What apparatus• Soon RPM will be

connected to Hitachi• Every patient – every

field

Machine QA Scattered Beam - AnnualICRU 78 PTC H Practice

• X-ray positioning and alignment systems

• CT Hounsfield number calibration

• Comprehensive tests of therapy equipment:

• X-ray positioning and alignment systems

• CT Hounsfield number calibration all CT scanners

• Comprehensive tests of • Comprehensive tests of

therapy equipment:– Monitor chambers, timers,

beam-delivery termination and control interlocks, stray radiation, gantry isocenter, depth-dose and lateral profiles, baseline date for daily QA checks.

• Comprehensive tests of therapy equipment:– Monitor chambers, beam-

delivery termination and control interlocks, gantry isocenter, depth-dose and lateral profiles, baseline for daily QA checks.

The setup of Gantry rotation isocenter versus couch mechanical isocenter using

2mm sphere in X-ray mode.

The cage x-ray tube and FPD are extended. They must be retracted before we can move the gantry. This safety requirement is a pain.

G1 2010 Medium ScatterRange and SOBP Widths Annual

Note different

SOBP widths

Range: within 2 mm of baseline SOBP: within 5 mm of baseline

G1 Distal Penumbra 80% to 20%

2010 vs. Commissioning

G1 Annual Independent Output Check Radiological Physics Center

Patient Treat Field Output Measurement – G1

Example of a typical form used to established the MUs established the MUs for scattered beam treatments.

Pristine Bragg Peak TPS Input Data – Also in air spot profilesMonte Carlo Calculated and Measured Normalization Dose in Gy/MU versus range Normalization measurements: 2 cm depth, 8 cm chamber

94 Energies: Ranges from 4.0 cm to 30.6 cm

Spots are not pencils.Low energy spots have issues.

FWHM

Gillin et al. Med Phys 2010

Scanned Beam Patient QAA 3D Dosimetry Challenge

SFO, SFIB, MFO• SFO – Single Field Optimization• SFIB – Single Field Integrated Boost• MFO – Multi-Field Optimization

• Currently 1 MFO patient – every other week• 3D dosimetric system(s) needed to meet this 3D

challenge• Standards for patient QA are evolving• 4 + minutes are required to run a field from the EMR,

which includes uploading from EMR, Rx machine preparation, Rx delivery, and downloading to EMR

Terminology• In treatment planning of spot scanning proton therapy

(SSPT), the weight of each spot is optimized using an inverse planning process with or without dose constraints to the target volumes and critical structures.

• Multi-field optimization (MFO) –Intensity modulated proton therapy (IMPT)– All spots from all fields are optimized simultaneously– All spots from all fields are optimized simultaneously

• Single field optimization (SFO) - Each field is optimized to deliver the prescribed dose to target volume:– Single field uniform dose (SFUD)– Single field integrated boost (SFIB)

Scanned Beam Patient QA

• 2D measurements are routinely made with the Matrixx ion chamber array and solid water

• Note Energy Absorber (EA) in snout, which will be supported in the Spring, 2011 clinical release of Eclipse and will eliminate the need for many low energy beams.

Scanned Beam Patient QASFO, SFIB, MFO

• 1 to 4 hrs Physics plan review• ~ 1 hr EMR QA Rx Delivery• ~ 1 hr Verification plan• 1 to 6 hrs 2D % DD in multiple plans• 1 to 6 hrs 2D % DD in multiple plans• 1 hr % DD using Advanced

Markus Chamber• 4 to 12 hrs Total per patient• First MFO patient 120 hrs +. Patient not treated

with MFO technique, based upon Physics recommendation

Machine QA Scanned Beam - DailyICRU 78 PTC H Practice

• Dose rate and monitor issues• Performance of beam position

monitors• Depth dose curve in a water

phantom

• Interlocks/Communication• Monitors – 3 energies per day• 5 spot positions • Depth dose in a water

phantom Not donephantom

• Calibration of primary dose monitor

• Dose at several spots and depths

• Data flow between EMR and delivery system

• Alignment of the proton central ray and the x-ray system

Machine QA Scanned Beam - WeeklyICRU 78 PTC H Practice

• Qualitative 3-D checkof the outline and range of dose distribution for one patient’s irradiation

• Output check for three standard 1 liter patterns, which involve all energies –a single point patient’s irradiation

field in water phantom• Definition of 3D check

needs to be established.

a single point measurement.

• Quantitative 2D QA is performed on each patient at several depths

Machine QA Scanned Beam –Semi-annual

ICRU 78 PTC H Practice• Calibration of primary dose

monitor and the phase space of the beam tunes

• What is the phased space of

• Weekly primary monitor calibration checks.

• Beam steering is performed weekly to align the spot to the central ray. Pause or alarm signals are a regular

• What is the phased space of beam tunes?

• Clinical physics understands that beam tunes are related to the operating conditions of the accelerator. Beam steering is the use of the bending magnets to steer the beam to the center of the nozzle for each gantry angle.

signals are a regular occurrence. Tuning the synchrotron may be performed daily.

• Spot size and position are checked with each spot delivered.

Machine QA Scanned Beam – AnnualICRU 78 PTC H Practice

• Check of the beam characteristics– Calibration of the whole

dosimetry system,

• Check mechanicals• Check imaging system• Check of the beam

characteristics– Calibration of the whole dosimetry system,

performance of the scanning system in terms of dose linearity and dose rate dependence.

– Calibration of the whole dosimetry system, performance of the scanning system in terms of dose linearity and dose rate dependence.

– End effect for very small MUs.

End Effect for G30.005 MU to 0.04 MU

• The maximum number of MUs for the discrete spot scanning beam is 0.04, while the minimum is 0.005. The end effect was studied using the Bragg Peak chamber at a depth of 2 cm for both the lowest energy beam and the highest energy beam. The same number of MU’s (10) were delivered using 0.005 MU/spot (2000 spots), 0.01 were delivered using 0.005 MU/spot (2000 spots), 0.01 MU/spot (1000 spots), and 0.04 MU per spot (250 spots). Ionization was measured and the results were normalized to the readings for 0.04 MU/spot. The measured outputs were within one percent the same. Thus, within the allowed range of spots, there is no significant difference in the dose delivered, independent of the dose per spot.

Gillin et al. Med. Phys. 2010

G3 Annual %DD Measured on 5 Different Beams

Energy Requested Range Measured Range

• MeV cm cm• 221.8 30.6 30.7• 201.0 25.8 25.9• 201.0 25.8 25.9• 185.7 20.5 20.6• 96.4 7.0 7.0• 72.6 4.0 4.0

Point by point measurements for a set number of MUs is the general approach. Ranges are confirmed for only a limited number of energies.

G3 TLD Report from RPC

ICRU 789.4 Examples of Periodic Checks

• … The procedures for scanned beams are given mostly in terms of dosimetric issues, as the check of dose delivery is the most important task.important task.

• Better tools are needed.

Scanned Beam Patient QAat PTC H

• MUs are provided by the TPS and confirmed through measurements.

• Before treatment at least one delivery of each field must be performed using the EMR and the delivery system, in order to upload the bending magnet currents to the EMR.EMR.

• The entire spot pattern is delivered for each measurement. This requires at least four minutes of beam time per measurement.

• Patient dose measurements to confirm the dose at a single point, as performed for IMRT, have recently been abandoned for complex dose distributions, e.g. IMPT.

Zhu et al. IJRBP (in press)

Scanned Beam Patient QAProstate + SV

(SFO) March, 2011• 6 page report including 2D dose pattern• Table 1: Treatment field parameters• Prescription Isodose line: 98.2%• CTV (cc): 44.3 STV (cc): 116.3• CTV (cc): 44.3 STV (cc): 116.3• ARLPB Nominal range: 24.83 cm SOBP 9.51

cm, Max E 198.3 MeV, Layers 19, Raw spots 1429, MU 33.38

• Absolute dose at isocenter: TPS calculated physical dose (210.8/1.1 = 191.6 cGy). Measured dose 191.3 cGy.

Scanned Beam Patient QAProstate + SVMarch, 2011

• Central axis depth dose in a rectangular phantom – a 2D ion chamber array was used for CA depth dose measurements. used for CA depth dose measurements. Calculated values were obtained from a verification plan created for a solid water phantom in the TPS. Nominal SSD is 250 cm. Three points are measured: two points inside the SOBP and one point in the high-gradient distal fall-off region.

Fish bowl measurement to confirm MU’s.

Point dose MU measurements

Scanned Beam Patient QAProstate + SVMarch, 2011

• 2D dose distributions in planes perpendicular to beam direction at depths of 18.4 cm and 22.4 cm for each field. of 18.4 cm and 22.4 cm for each field. Both depths are inside the nominal SOBP. The criteria for acceptance is a works in progress. For prostate patients, 2% relative dose/2 mm works well.

Purple: 100%

Orange: 95%

Teal: 90%

Relative dose

comparison

Black: 80%

Blue: 20%

Matrixx: Solid lines TPS: Dashed lines

CTV-45 CTV-50

GTV-54GTV-54

Single Field Integrated Boost

Patient QA Scanning BeamSFIB

• 10 yo with infratentorial medulloblastoma. Boost portion treated with scanning beam. Right and left posterior brain boost and a PA spine boost. Depth dose PA spine boost. Depth dose measurements at two different locations for the spine boosts.

Scanned Beam Patient QABrian and Spine Boosts

(SFIB) March, 2011

• Prescription Isodose line: 100%• Brain CTV (cc): 205.1 STV (cc): 276.6• Spine CTV (cc): 19.1 STV (cc): 61.3• Spine CTV (cc): 19.1 STV (cc): 61.3• QRPPB (Brain) Nominal range: 13.61 cm SOBP

13.41 cm, Max E 136.4 MeV, Layers 43, Raw spots 2283, Post spots 3064, MU 78.78

• SPAPB (Spine) Nominal range: 10.2 cm SOBP 6.97 cm, Max E 118.6 MeV, Layers 32, Raw spots 1120, Post spots 4675, MU 166.26

Point MeasurementsPin Point Ion Chamber

These point dose measurements are no longer being performed.

Brain

Spine:

SFIB

Depth dose measurements: Red – Markus chamber. Green - Matrixx

Spine:

2 different

axes

Measured versus Calculated DosePurple 100%, Orange 90%, Teal 80%, Black 70%, … Blue 10%

Purple: 100%

Orange: 90%

Teal: 80%

Spine Field: Depth 6.4 cm Depth 10.4 cm

Black: 70%

Blue: 10%

Patient QA Scanning BeamMFO

• 44 yo with chondrosarcoma of the bones of the skull and face.

• 3 fields: right anterior oblique, ARAPB, PA, BPAPB, and a superior-inferior vertex BPAPB, and a superior-inferior vertex field, CSIPB.

• Prescription 70 CGE to the T_PTV70 in 35 fractions.

• T_GTV 10.1 cc, CTV 70 31.4 cc, T_PTV 70 57.3 cc

Dose measurements along defined axes with Markus and Matrixx

Approximate beam time for measurements: 2 hrs.

Measurements are in terms of ‘absolute’ dose.

Prior to use, Matrixx is ‘calibrated’ against known dose pattern.

Superior-Inferior Vertex Field2D Measurements in Solid Water

9.4 cm 13.4 cm

15.4 cm 17.4 cm

100% is defined has the maximum dose in each plane.

Patient QA Scanning BeamMFO

• 67 yo with base of tongue carcinoma.• 3 fields: right superior-inferior field (56 different

energies), left superior-inferior field (58 different energies), and PA field (60 different energies).

• Prescription 66 CGE to CTV1, 60 CGE to CTV2 and 54 CGE to CTV3.

• Prescription 66 CGE to CTV1, 60 CGE to CTV2 and 54 CGE to CTV3.

• 2D measurements at the gantry angle for each field• Dose measurements in Physics Mode at 270 degrees,

both depth dose profile comparison and 2D dose distribution in planes perpendicular to the beam direction.

H&N Planning – IMPT(MFO)

• 67 yr old male• Squamous cell carcinoma • Right base of tongue• CTV66, CTV60 & CTV54• 3 fields: G280° /C15°, G80°/C345° & G180° /C0°

Field 1 Field 2

G80°/C345° & G180° /C0°

Field 3

Field 1 Field 2

ARSPB Gantry: 280 degreesDepth 4.6 cm

CalculatedDose profile

Measured Gamma index map: 100% for 2% and 2 mm

BRSPB Gantry: 80 degreesDepth 7.0 cm

Measured Profiles

CalculatedGamma Index Map

CRSPB Gantry: 180 degreesDepth 4.5 cm

Measured Profiles

CalculatedGamma Index Map

ARSPB Gantry: 270 degreesDepth Dose Measurements 260 cm TSD

3 Different Axes – Same depths

BRSPB Gantry: 270 degreesDepth Dose Measurements 260 cm TSD

Four different axes

CRSPB Gantry: 270 degreesDepth Dose Measurements 260 cm TSD

Three different axes

ARSPB Gantry: 270 degrees2D Relative Dose Measurements 260 cm TSD

Depth: 4.4 cm

Depth:6.4 cm

Depth:

8.4 cm

Depth:

10.4 cmAgreement between TPS and measurement is good

CRSPB Gantry: 270 degrees2D Relative Dose Measurements 260 cm TSD

• Depth 10.4 cm• Relative dose comparison,

normalized to the highest dose in the plane. Multiple planes are studied.

• Absolute doses are measured along specific axes.along specific axes.

• Time intensive: Preparation time several hours, measurement time several hours, report generation time several hours, and review time 1 hour.

• Eclipse: Double Gaussian spot model.

Works-in-Progress AP/PA fields with Energy Absorber

EA will provide for faster for faster treatments with sharper penumbra, as higher energy protons will be used and fewer energy changes.

Edvard Munch,

1893

PTC H Summary

• Protons demand attention to details.• There is a substantial amount of clinical physics

work.• Time is the ultimate constraint. More efficient • Time is the ultimate constraint. More efficient

processes need to be developed.• Commissioning new versions of the TPS with

new features requires ~ 1 man year. • Long term upgrades to the imaging and delivery

systems remain a poorly defined challenge.

Protons: The Clinical Physics Full Employment Modality

• Dedicated Clinical Physics Team: Ron Zhu, Narayan Sahoo, Jim Lii, Richard Amos, Richard Wu, Falk Poenisch, Heng Li, Mengping Zhu, Craig Martin, Patrick Oliver, Brad Tailor + others who have moved on.

• Dedicated Physics Engineering team: Kazumichi Suzuki, Chuck Smith, MDACC engineers + Hitachi engineersChuck Smith, MDACC engineers + Hitachi engineers

• Dedicated Research Team: Radhe Mohan, Uwe Titt, Xiaodong Zhang, Dragan Mirkovic + others who have moved on.

• In addition, PTC H is a success thanks to the contributions made by the RTT’s, the CMD’s, and the MD’s.

Ranges (cm) (d 90%)24 different scattering conditions

Energy (MeV)

Small Snout

Medium Snout

Large Snout

250 32.4 28.5 25.0

225 26.9 23.6 20.6225 26.9 23.6 20.6

200 21.8 19.0 16.5

180 16.9 16.1 13.7

160 13.4 13.0 11.0

140 10.2 10.0 8.4

120 6.9 6.4 6.3

100 4.9 4.3 4.3

Point by Point Measurement of Depth Dose Curve

0.8

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Series1

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G1 2110 Mechanical/Radiation Tests