Utility of Smart Arc CDR for intensity-modulated radiation therapy for prostate cancer

The objective of this study was to clarify the utility of CDR mode for prostate IMRT. Pinnacle3 and Clinac 21EX linac (Varian, 10 MV X-rays) were used for planning. The plans were created for 28 patients using a fixed multi-field IMRT (f-IMRT), VMAT and CDR techniques. The dose distribution results were classified into three groups: optimal, suboptimal and reject. For the f-IMRT, VMAT and CDR results, 25, 26 and 21 patients were classified as ‘optimal’, respectively. Our results show a significant reduction in the achievement rate of ‘optimal’ for a CDR when the bladder volume is <100 cm3. The total numbers of monitoring units (MUs) (average ± 1) were 469 ± 53, 357 ± 35 and 365 ± 33; the average optimization times were ~50 min, 2 h and 2 h 40 min, and the irradiation times were ~280 s, 60 s and 110 s, respectively. CDR can reduce the total MUs and irradiation time compared with f-IMRT, and CDR has a lower initial cost compared with VMAT. Thus, for institutions that do not currently perform VMAT, CDR is a useful option. Additionally, in the context of patient identification, bladder volume may be useful.
Source: Journal of Radiation Research - Category: Physics Authors: Tags: Oncology Source Type: research