9a. Therefore, it is important to consider the dynamics of both parameters in evaluating impact, especially if only one of the above two tests are performed. Looking at V100 in isolation obscures, the inherent bias toward overtreatment, as a plan generated for a high Docetaxel volume target is more likely to encompass the volumes of other observers and result in good coverage. In this article, we presented a volumetric and dosimetric evaluation of our semiautomatic prostate segmentation algorithm (TES) for ultrasound images (17). In the volumetric evaluation,

our results on 140 cases showed that an average whole gland volume error of less than 7% exists between surfaces created from Raw TES CTV’s and RO-reviewed TES CTV’s. This value is less in the midgland, as expected, 17-AAG where the prostate boundary is more visible, and is higher in the apex. In the dosimetric evaluation (41 cases), we measured the difference between the V100 and CI100 dose parameters of treatment plans created for the Raw TES PTV, used

as the baseline, and treatment plans created for the Raw TES PTV’s but overlaid on RO-reviewed TES PTV’s. The mean decrease in V100 and CI100 was less than 5% and 0.2, respectively, in all regions of the gland. The greatest degradation in quality occurred in the posterior base and apex, and anterior base and apex for the V100, and in the apex for the CI100. However, this study has demonstrated, in a subset analysis of 5 cases with 10 blinded observers, that any differences in the

distribution of dose when planning using TES contours are largely comparable with manual dosimetric variability between observers. Moreover, this variability only considered a single institution and may be even greater between experts at different institutions because of diversity in training backgrounds and treatment strategies. We observed that poor image quality could in some cases lead to unsatisfactory results. However, the algorithm is guided by the manually selected initial midgland boundary points and the positions of the base and apex from which initial contours and surfaces are produced. Because the edge detection is performed Urease within a certain limit of these initial contours and surfaces, artifacts inside the prostate such as calcifications should not pose a problem and, as long as the image quality at midgland is adequate for the observer to perform initialization, our method should provide consistent results. Our program regards the reproducibility of the alignment between the prostate, the probe and the patient’s craniocaudal axes to be important, as the accurate registration of the preplanned PTV with the prostate as visualized on the day of the implant to be a vital component in streamlining the procedure and reducing setup complications. This is facilitated by ensuring that the prostate is positioned so as to have midsagittal symmetry in the planning images.