Prospective clinical validation of independent DVH prediction for plan QA in automatic treatment planning for prostate cancer patients.

Abstract

To prospectively investigate the use of an independent DVH prediction tool to detect outliers in the quality of fully automatically generated treatment plans for prostate cancer patients. A plan QA tool was developed to predict rectum, anus and bladder DVHs, based on overlap volume histograms and principal component analysis (PCA). The tool was trained with 22 automatically generated, clinical plans, and independently validated with 21 plans. Its use was prospectively investigated for 50 new plans by replanning in case of detected outliers. For rectum D_mean, V_65Gy, V_75Gy, anus D_mean, and bladder D_mean, the difference between predicted and achieved was within 0.4 Gy or 0.3% (SD within 1.8 Gy or 1.3%). Thirteen detected outliers were re-planned, leading to moderate but statistically significant improvements (mean, max): rectum D_mean (1.3 Gy, 3.4 Gy), V_65Gy (2.7%, 4.2%), anus D_mean (1.6 Gy, 6.9 Gy), and bladder D_mean (1.5 Gy, 5.1 Gy). The rectum V_75Gy of the new plans slightly increased (0.2%, p = 0.087). A high accuracy DVH prediction tool was developed and used for independent QA of automatically generated plans. In 28% of plans, minor dosimetric deviations were observed that could be improved by plan adjustments. Larger gains are expected for manually generated plans.