PURPOSE: To demonstrate the technical feasibility of intensity modulated radiation therapy (IMRT) dose painting using (11)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 had (11)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 (SUV(60%) and SUV(70%)). Three IMRT plans were generated for each patient: PLAN(78), which consisted of whole-prostate radiation therapy to 78 Gy; PLAN(78-90), which consisted of whole-prostate RT to 78 Gy, a boost to the SUV(60%) to 84 Gy, and a further boost to the SUV(70%) to 90 Gy; and PLAN(72-90), which consisted of whole-prostate RT to 72 Gy, a boost to the SUV(60%) to 84 Gy, and a further boost to the SUV(70%) 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 (TCP(PET)) and on prostatectomy-defined volumes (TCP(path)), 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. TCP(PET) values for PLAN(78), PLAN(78-90), and PLAN(72-90) were 65%, 97%, and 96%, respectively. TCP(path) values were 71%, 97%, and 89%, respectively. Both PLAN(78-90) and PLAN(72-90) had significantly higher TCP(PET) (P=.002 and .001) and TCP(path) (P<.001 and .014) values than PLAN(78). PLAN(78-90) and PLAN(72-90) were not significantly different in terms of TCP(PET) or TCP(path). There were no significant differences in rectal NTCPs between the 3 plans.
CONCLUSIONS: IMRT dose painting for localized prostate cancer using (11)C-choline PET scans is technically feasible. Dose painting results in higher TCPs without higher NTCPs.
Written by:
Chang JH, Lim Joon D, Lee ST, Gong SJ, Anderson NJ, Scott AM, Davis ID, Clouston D, Bolton D, Hamilton CS, Khoo V Are you the author?
Radiation Oncology Centre, Austin Health, Victoria, Australia; University of Melbourne, Victoria, Australia
Reference: Int J Radiat Oncol Biol Phys. 2012 Aug 1;83(5):e691-6
doi: 10.1016/j.ijrobp.2012.01.087
PubMed Abstract
PMID: 22658218