Dosimetric Study of Pelvic Proton Radiotherapy for High-Risk Prostate Cancer

Journal Article · Sun Nov 15 00:00:00 EST 2009 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.01.044· OSTI ID:21367491

Chera, Bhishamjit S ^[1]; Vargas, Carlos ^[2]; Morris, Christopher G ^[1]; Louis, Debbie; Flampouri, Stella; Yeung, Daniel; Duvvuri, Srividya; Zuofeng, Li ^[3]

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1. University of Florida Department of Radiation Oncology, Gainesville, FL (United States)
2. Boca Radiation Oncology Associates, Boca Raton, FL (United States)
3. University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

Purpose: To compare dose distributions in targeted tissues (prostate, seminal vesicles, pelvic regional nodes) and nontargeted tissues in the pelvis with intensity-modulated radiotherapy (IMRT) and forward-planned, double-scattered, three-dimensional proton radiotherapy (3D-PRT). Methods and Materials: IMRT, IMRT followed by a prostate 3D-PRT boost (IMRT/3D-PRT), and 3D-PRT plans were created for 5 high-risk prostate cancer patients (n = 15 plans). A 78-CGE/Gy dose was prescribed to the prostate and proximal seminal vesicles and a 46-CGE/Gy was prescribed to the pelvic nodes. Various dosimetric endpoints were compared. Results: Target coverage of the prostate and nodal planning target volumes was adequate for all three plans. Compared with the IMRT and IMRT/3D-PRT plans, the 3D-PRT plans reduced the mean dose to the rectum, rectal wall, bladder, bladder wall, small bowel, and pelvis. The relative benefit of 3D-PRT (vs IMRT) at reducing the rectum and rectal wall V5-V40 was 53% to 71% (p < 0.05). For the bladder and bladder wall, the relative benefit for V5 to V40 CGE/Gy was 40% to 63% (p < 0.05). The relative benefit for reducing the volume of small bowel irradiated from 5 to 30 CGE/Gy in the 3D-PRT ranged from 62% to 69% (p < 0.05). Use of 3D-PRT did not produce the typical low-dose 'bath' of radiation to the pelvis seen with IMRT. Femoral head doses were higher for the 3D-PRT. Conclusions: Use of 3D-PRT significantly reduced the dose to normal tissues in the pelvis while maintaining adequate target coverage compared with IMRT or IMRT/3D-PRT. When treating the prostate, seminal vesicles, and pelvic lymph nodes in prostate cancer, proton therapy may improve the therapeutic ratio beyond what is possible with IMRT.

• OSTI ID: 21367491
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 75, Issue 4; Other Information: DOI: 10.1016/j.ijrobp.2009.01.044; PII: S0360-3016(09)00140-0; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0360-3016
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
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RADIOTHERAPY
RECTUM
THREE-DIMENSIONAL CALCULATIONS
BARYONS
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