Open AccessProximal seminal vesicle displacement and margins for prostate cancer radiotherapy
Author(s) -
Lim Joon Daryl,
Chao Michael,
Piccolo Angelina,
Schneider Michal,
Anderson Nigel,
Handley Monica,
Benci Margaret,
Ong Wee Loon,
Daly Karen,
Morrell Rebecca,
Wan Kenneth,
Lawrentschuk Nathan,
Foroudi Farshad,
Jenkins Trish,
Angus David,
Wada Morikatsu,
Sengupta Shomik,
Khoo Vincent
Publication year - 2021
Publication title -
journal of medical radiation sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 18
eISSN - 2051-3909
pISSN - 2051-3895
DOI - 10.1002/jmrs.457
Subject(s) - prostate cancer , prostate , medicine , confidence interval , fiducial marker , radiation therapy , urology , nuclear medicine , surgery , radiology , cancer
Guidelines recommend that the proximal seminal vesicles (PrSV) should be included in the clinical target volume for locally advanced prostate cancer patients undergoing radiotherapy. Verification and margins for the prostate may not necessarily account for PrSV displacement. The purpose was to determine the inter‐fraction displacement of the PrSV relative to the prostate during radiotherapy. Methods Fiducials were inserted into the prostate, and right and left PrSV (RSV and LSV) in 30 prostate cancer patients. Correctional shifts for the prostate, right and left PrSV and pelvic bones were determined from each patient's 39 daily orthogonal portal images relative to reference digitally reconstructed radiographs. Results There was a significant displacement of the RSV relative to the prostate in all directions: on average 0.38 mm (95% confidence interval (CI) 0.26 to 0.50) to the left, 0.80–0.81 mm (CI 0.68 to 0.93) superiorly and 1.51 mm (CI 1.36 to 1.65) posteriorly. The LSV was significantly displaced superiorly to the prostate 1.09–1.13 mm (CI 0.97 to 1.25) and posteriorly 1.81 mm (CI 1.67 to 1.96), but not laterally (mean 0.06, CI −0.06 to 0.18). The calculated PTV margins (left–right, superior–inferior, posterior–anterior) were 4.9, 5.3–5.6 and 4.8 mm for the prostate, 5.2, 7.1–8.0 and 9.7 mm for the RSV, and 7.2, 7.5–7.6 and 8.6 mm for the LSV. Conclusion There is a significant displacement of the PrSV relative to the prostate during radiotherapy. Greater margins are recommended for the PrSV compared to the prostate.