Targeting Issues For Proton Treatments Of The Prostate SJ Rosenthal Ph.D., JA Wolfgang Ph.D., Sashi Kollipara Departme

1. 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

3. 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

4. History of Proton Prostate Therapy 1982 Perineal Proton Boost for Prostate Protocol Up to 75.6 CGE -1992 Used 160 MeV Beam at Harvard Cyclotron Laboratory Rectal Probe to Immobilize Prostate Radiographic Set Up 1995 Perineal Boost Increased to 79CGE At HCL -2000 Boost with Probe Delivered First to Reduce Toxicity 1991 LLUMC Proton Only with Lateral Fields - 2002 Retained 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 2002 Prostate Dose Escalation Protocol Up to 84.6 CGE

5. Pencil Beam vs. Broad Beam

6. 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

8. Gold Seeds in Prostate

9. Prostate Seed Daily Motion First Three Patients Patient 1 Patient 3 Patient 2

10. 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

11. Setup Error Analysis Standard Deviation averaged about 2 mm per patient Setup error could be as large as 0.5 – 1.0 cm

12. Increasing the Compensator Smear From 5 to 10 mm 5 mm Smear 10 mm Smear Actually Improves Femoral Head Sparing and Prostate Coverage

13. 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

14. 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

15. Minimum Dose To Prostate As Planned No Shift Shifted Prostate With Tracking 100 99 95 90 75 50

16. Maximum Dose To Femoral Heads As Planned No Shift With Prostate Tracking 99 95 90 75 50 43 40 40 % Isodose 43 % Isodose

17. 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