Targeting Issues For Proton Treatments Of The Prostate
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Targeting Issues For Proton Treatments Of The Prostate SJ Rosenthal Ph.D., JA Wolfgang Ph.D., Sashi Kollipara Department of Radiation Oncology PowerPoint PPT Presentation


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Targeting Issues For Proton Treatments Of The Prostate SJ Rosenthal Ph.D., JA Wolfgang Ph.D., Sashi Kollipara Department of Radiation Oncology Massachusetts General Hospital, Boston MA. History of Proton Prostate Therapy Issue of Proton Scatter Issue of Organ Motion

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Targeting Issues For Proton Treatments Of The Prostate SJ Rosenthal Ph.D., JA Wolfgang Ph.D., Sashi Kollipara Department of Radiation Oncology

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Targeting Issues For Proton Treatments Of The Prostate

SJ Rosenthal Ph.D., JA Wolfgang Ph.D., Sashi Kollipara

Department of Radiation Oncology

Massachusetts General Hospital, Boston MA


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History of Proton Prostate Therapy

Issue of Proton Scatter

Issue of Organ Motion

Setting Compensator Smear

Patient/Organ Set Up Technique

Early Patient Study

Range Compensator Strategy


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History of Proton Prostate Therapy

1982 Perineal Proton Boost for Prostate Protocol Up to 75.6 CGE

-1992Used 160 MeV Beam at Harvard Cyclotron Laboratory

Rectal Probe to Immobilize Prostate

Radiographic Set Up

1995Perineal Boost Increased to 79CGE At HCL

-2000Boost with Probe Delivered First to Reduce Toxicity

1991LLUMC Proton Only with Lateral Fields

- 2002Retained Probe for Alignment

2002 NPTC Study of Proton Treatments of the Prostate

Lateral Fields Plan Optimized with Pencil Beam Calculation

Organ Motion Adjustments - No Probe

Digital Radiography for Rapid Set Up and Seed Tracking

2002Prostate Dose Escalation Protocol Up to 84.6 CGE


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Pencil Beam vs. Broad Beam


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Pencil Beam Calculation Needed to Insure Distal Coverage

Broad Beam Calculation

Cold Target when Broad Beam Calculation is Used

Add 1 cm to Range and Modulation for Good Coverage with Pencil Beam Calculation

Pencil Beam Calculation


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Gold Seeds in Prostate


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Prostate Seed Daily Motion First Three Patients

Patient 1

Patient 3

Patient 2


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Daily Treatment Set Up 6 Prostate Patients

  • Monitored position of prostate by marking position of seeds relative to original setup simulation position

  • Perform statistical analysis of observed setup error for six patients

  • Take average setup error after N (Ö total fractions) treatments and apply it to remaining treatments


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Setup Error Analysis

Standard Deviation averaged about 2 mm per patient

Setup error could be as large as 0.5 – 1.0 cm


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Increasing the Compensator Smear From 5 to 10 mm

5 mm Smear

10 mm Smear

Actually Improves Femoral Head Sparing and Prostate Coverage


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Increasing the Compensator Smear From 5 to 10 mm

Prostate 5 mm Smear

Prostate 10 mm Smear

Anterior Rectum 10 mm Smear

Anterior Rectum 5 mm Smear

Allows for prostate to bony anatomy mis-registration up to 1 cm


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Consequences of Prostate Motion and Re -Targeting

Create Shifted Prostate Target to Simulate

Movement in Treatment Plan

GTV Draw by MD

GTV Draw by MD

GTV with 1cm

Shift Inferior

GTV with 1cm

Shift Inferior

Target Beam to Shifted Prostate but Retain Aperture

and Compensator designed to Original Target


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Minimum Dose To Prostate

As Planned No Shift

Shifted Prostate With Tracking

100

99

95

90

75

50


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Maximum Dose To Femoral Heads

As Planned No Shift

With Prostate Tracking

99

95

90

75

50

43

40

40 % Isodose

43 % Isodose


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Dose to Femoral Heads and Prostate in Fixed and Shifted Plans

Prostate Fixed Plan

Femoral Heads Fixed Plan

Shifted Prostate Shifted Plan

Femoral Heads Shifted Plan


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