Anatomical aspects of vessel-sparing radiation therapy for prostate cancer

Aim. To assess the impact of topographic anatomy of the critical structures of the penile vessels on the implementation of vessel-sparing radiation therapy for prostate cancer.Materials and methods. The study included 70 patients with verified prostate cancer. All patients underwent topometric computed tomography and magnetic resonance imaging. The target (prostate gland and proximal third of the seminal vesicles), standard critical structures (rectum, bladder, femoral heads), as well as critical vascular structures responsible for erectile function were delineated (bulb of the penis, crura of the corpus cavernosum, internal pudendal artery). The obtained images were subjected to volumetric and spatial analysis using the Eclipse 4.0 (Varian Medical System) planning system.Results. In all 70 patients, adequate visualization of all anatomical structures was achieved. The mean distance between the apex and the penile bulb was 1.35 ± 0.47 (0.35–2.41) cm. In the majority of patients, this index exceeded 1 cm: up to 1 cm – 18 (25.7 %), between 1.1 and 1.5 – 27 (38.6 %), and more than 1.51 cm – 25 (35.7 %). The apical-cavernous distance on the right and left did not differ significantly: 2.05 ± 0.45 (1.12–3.00) and 2.09 ± 0.44 (1.16–3.02) cm, respectively. The internal pudendal artery in the projection of the irradiated volume (prostate gland and proximal third of seminal vesicles) is located at an average distance of 2.5 cm (apex gland) to 4.3 cm (basal parts of the prostate). Analysis (Spearman’s correlation coefficient) did not reveal a significant relationship between the assessed spatial parameters and prostate volume and body mass index.Conclusion. The topographic relationship between the irradiated volumes and erectile vascular structures makes it possible to implement vessel-sparing radiation therapy protocol in the majority of cases (about 75 %).