Intensity modulated radiation therapy dose painting for localized prostate cancer using ¹¹C-choline positron emission...

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.

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.

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.

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.