Neurovascular bundle–sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study

Journal Article · Fri Jan 01 00:00:00 EST 2016 · Medical Dosimetry

DOI:https://doi.org/10.1016/J.MEDDOS.2016.08.003· OSTI ID:22685171

Yang, X.; Liu, T.; Thomas, M. ^[1]; Nour, S. G. ^[2]; Jani, A. B. ^[1]

---

1. Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States)
2. Department of Radiology, Emory University, Atlanta, GA (United States)

Purpose: Sexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie posterolaterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the dosimetric feasibility of “NVB-sparing” prostate radiotherapy while still delivering adequate dose to the prostate. Methods: Twenty-five consecutive patients with prostate cancer (with no extraprostatic disease on pelvic magnetic resonance imaging [MRI]) who that were treated with external beam radiotherapy, with the same primary planning target volume margins, to a dose of 79.2 Gy were evaluated. Pelvic MRI and simulation computed tomography scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy plan was generated using the NVB bilaterally with 2 mm margin as an organ to spare and compared to the patient’s previously delivered plan. Dose-volume histogram endpoints for NVB, rectum, bladder, and planning target volume 79.2 were compared between the 2 plans using a 2-tailed paired t-test. Results: The V70 for the NVB was significantly lower on the NVB-sparing plan (p <0.01), while rectum and bladder endpoints were similar. Target V100% was similar but V{sub 105%} was higher for the NVB-sparing plans (p <0.01). Conclusions: “NVB-sparing” radiotherapy is dosimetrically feasible using CT-MRI registration, and for volumetric modulated arc therapy technology — target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVB-sparing” radiotherapy is currently under study at our institution.

• OSTI ID: 22685171
• Journal Information: Medical Dosimetry, Vol. 41, Issue 4; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0958-3947
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
62 RADIOLOGY AND NUCLEAR MEDICINE
BEAMS
BLADDER
COMPARATIVE EVALUATIONS
COMPUTER CODES
COMPUTERIZED TOMOGRAPHY
FEASIBILITY STUDIES
HAZARDS
LIMITING VALUES
MAGNETIC RESONANCE
NEOPLASMS
NMR IMAGING
PATIENTS
PLANNING
PROFITS
PROSTATE
RADIOTHERAPY
RECTUM
SIMULATION
TOXICITY
UROGENITAL SYSTEM DISEASES
WEIGHT
WHO