Intensity Modulated Radiation Therapy Dose Painting for Localized Prostate Cancer Using11 C-choline Positron Emission Tomography Scans

Purpose To demonstrate the technical feasibility of intensity modulated radiation therapy (IMRT) dose painting using11 C-choline positron emission tomography PET scans in patients with localized prostate cancer. Methods and Materials This was an RT planning study of 8 patients with prostate cancer who had11 C-choline PET scans prior to radical prostatectomy. Two contours were semiautomatically generated on the basis of the PET scans for each patient: 60% and 70% of the maximum standardized uptake values (SUV60% and SUV70% ). Three IMRT plans were generated for each patient: PLAN78 , which consisted of whole-prostate radiation therapy to 78 Gy; PLAN78-90 , which consisted of whole-prostate RT to 78 Gy, a boost to the SUV60% to 84 Gy, and a further boost to the SUV70% to 90 Gy; and PLAN72-90 , which consisted of whole-prostate RT to 72 Gy, a boost to the SUV60% to 84 Gy, and a further boost to the SUV70% to 90 Gy. The feasibility of these plans was judged by their ability to reach prescription doses while adhering to published dose constraints. Tumor control probabilities based on PET scan-defined volumes (TCPPET ) and on prostatectomy-defined volumes (TCPpath ), and rectal normal tissue complication probabilities (NTCP) were compared between the plans. Results All plans for all patients reached prescription doses while adhering to dose constraints. TCPPET values for PLAN78 , PLAN78-90 , and PLAN72-90 were 65%, 97%, and 96%, respectively. TCPpath values were 71%, 97%, and 89%, respectively. Both PLAN78-90 and PLAN72-90 had significantly higher TCPPET ( P =.002 and .001) and TCPpath ( P