TY - JOUR
T1 - Dosimetric Changes Resulting From Patient Rotational Setup Errors in Proton Therapy Prostate Plans
AU - Sejpal, Samir V.
AU - Amos, Richard A.
AU - Bluett, Jaques B.
AU - Levy, Lawrence B.
AU - Kudchadker, Rajat J.
AU - Johnson, Jennifer
AU - Choi, Seungtaek
AU - Lee, Andrew K.
PY - 2009/9/1
Y1 - 2009/9/1
N2 - Purpose: To evaluate the dose changes to the target and critical structures from rotational setup errors in prostate cancer patients treated with proton therapy. Methods and Materials: A total of 70 plans were analyzed for 10 patients treated with parallel-opposed proton beams to a dose of 7,600 60Co-cGy-equivalent (CcGE) in 200 CcGE fractions to the clinical target volume (i.e., prostate and proximal seminal vesicles). Rotational setup errors of +3°, -3°, +5°, and -5° (to simulate pelvic tilt) were generated by adjusting the gantry. Horizontal couch shifts of +3° and -3° (to simulate longitudinal setup variability) were also generated. Verification plans were recomputed, keeping the same treatment parameters as the control. Results: All changes shown are for 38 fractions. The mean clinical target volume dose was 7,780 CcGE. The mean change in the clinical target volume dose in the worse case scenario for all shifts was 2 CcGE (absolute range in worst case scenario, 7,729-7,848 CcGE). The mean changes in the critical organ dose in the worst case scenario was 6 CcGE (bladder), 18 CcGE (rectum), 36 CcGE (anterior rectal wall), and 141 CcGE (femoral heads) for all plans. In general, the percentage of change in the worse case scenario for all shifts to the critical structures was <5%. Deviations in the absolute percentage of volume of organ receiving 45 and 70 Gy for the bladder and rectum were <2% for all plans. Conclusion: Patient rotational movements of 3° and 5° and horizontal couch shifts of 3° in prostate proton planning did not confer clinically significant dose changes to the target volumes or critical structures.
AB - Purpose: To evaluate the dose changes to the target and critical structures from rotational setup errors in prostate cancer patients treated with proton therapy. Methods and Materials: A total of 70 plans were analyzed for 10 patients treated with parallel-opposed proton beams to a dose of 7,600 60Co-cGy-equivalent (CcGE) in 200 CcGE fractions to the clinical target volume (i.e., prostate and proximal seminal vesicles). Rotational setup errors of +3°, -3°, +5°, and -5° (to simulate pelvic tilt) were generated by adjusting the gantry. Horizontal couch shifts of +3° and -3° (to simulate longitudinal setup variability) were also generated. Verification plans were recomputed, keeping the same treatment parameters as the control. Results: All changes shown are for 38 fractions. The mean clinical target volume dose was 7,780 CcGE. The mean change in the clinical target volume dose in the worse case scenario for all shifts was 2 CcGE (absolute range in worst case scenario, 7,729-7,848 CcGE). The mean changes in the critical organ dose in the worst case scenario was 6 CcGE (bladder), 18 CcGE (rectum), 36 CcGE (anterior rectal wall), and 141 CcGE (femoral heads) for all plans. In general, the percentage of change in the worse case scenario for all shifts to the critical structures was <5%. Deviations in the absolute percentage of volume of organ receiving 45 and 70 Gy for the bladder and rectum were <2% for all plans. Conclusion: Patient rotational movements of 3° and 5° and horizontal couch shifts of 3° in prostate proton planning did not confer clinically significant dose changes to the target volumes or critical structures.
KW - Dosimetry
KW - Prostate cancer
KW - Proton therapy
KW - Rotational setup errors
KW - Treatment planning
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U2 - 10.1016/j.ijrobp.2008.08.042
DO - 10.1016/j.ijrobp.2008.08.042
M3 - Article
C2 - 19058919
AN - SCOPUS:68649113548
SN - 0360-3016
VL - 75
SP - 40
EP - 48
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 1
ER -