Purpose: To generate a reproducible step-wise guideline for the delineation of the lumbosacral plexus (LSP) on axial computed tomography (CT) planning images and to provide a preliminary dosimetric analysis on 15 representative patients with rectal or anal cancers treated with an intensity-modulated radiotherapy (IMRT) technique.
Methods And Materials: A standardized method for contouring the LSP on axial CT images was devised. The LSP was referenced to identifiable anatomic structures from the L4-5 interspace to the level of the sciatic nerve. It was then contoured retrospectively on 15 patients treated with IMRT for rectal or anal cancer. No dose limitations were placed on this organ at risk during initial treatment planning. Dosimetric parameters were evaluated. The incidence of radiation-induced lumbosacral plexopathy (RILSP) was calculated.
Results: Total prescribed dose to 95% of the planned target volume ranged from 50.4 to 59.4 Gy (median 54 Gy). The mean (± standard deviation [SD]) LSP volume for the 15 patients was 100 ± 22 cm(3) (range, 71-138 cm(3)). The mean maximal dose to the LSP was 52.6 ± 3.9 Gy (range, 44.5-58.6 Gy). The mean irradiated volumes of the LSP were V40Gy = 58% ± 19%, V50Gy = 22% ± 23%, and V55Gy = 0.5% ± 0.9%. One patient (7%) was found to have developed RILSP at 13 months after treatment.
Conclusions: The true incidence of RILSP in the literature is likely underreported and is not a toxicity commonly assessed by radiation oncologists. In our analysis the LSP commonly received doses approaching the prescribed target dose, and 1 patient developed RILSP. Identification of the LSP during IMRT planning may reduce RILSP. We have provided a reproducible method for delineation of the LSP on CT images and a preliminary dosimetric analysis for potential future dose constraints.
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http://dx.doi.org/10.1016/j.ijrobp.2011.11.074 | DOI Listing |
Front Oncol
November 2024
University of Iowa Health Care, Department of Radiation Oncology, Iowa City, IA, United States.
This retrospective study evaluates the dosimetric benefits of adaptive radiotherapy for head and neck cancer patients. Five patients with node-positive oropharyngeal squamous cell carcinoma were treated with MR-guided radiotherapy using the Elekta Unity MR-Linac, undergoing 3-4 offline adaptive plan modifications during their treatment. This study compared the dose delivered to organs at risk (OARs) in a full offline adaptive approach versus an approach accounting only for daily setup.
View Article and Find Full Text PDFPhys Med
November 2024
Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA; Maryland Proton Treatment Center, Baltimore, MD, USA.
Purpose: To explore the feasibility of a novel intensity-modulated proton arc technique that uses a single-energy beam from the cyclotron. The beam energy is externally modulated at each gantry angle by a tertiary energy modulator (EM). We hypothesize that irradiating in an arc without requiring an energy change from the cyclotron will achieve a faster delivery (main advantage of our technique) while keeping clinically desirable dosimetric results.
View Article and Find Full Text PDFPract Radiat Oncol
September 2024
Sheba Medical Center, Tel Aviv University, Tel Aviv-Yafo, Israel.
Purpose: Radiation therapy (RT) is a critical treatment modality for both primary and metastatic brain tumors, yet ∼30% of patients experience cognitive decline post-RT. This cognitive toxicity is linked to low radiation doses affecting the hippocampal dentate gyrus. Hippocampal avoidance-whole brain RT combined with memantine has shown promising outcomes in preserving cognitive function and quality of life in patients with brain metastases.
View Article and Find Full Text PDFBreast
December 2024
Department of Radiation Oncology, Taichung Veterans General Hospital, Taichung, Taiwan. Electronic address:
Introduction: We compared the dosimetric characteristics of the target and organs at risk (OARs) as well as the preliminary clinical outcomes between two accelerated partial breast irradiation (APBI) techniques.
Methods: Forty-four patients diagnosed with left-sided early breast cancer who underwent APBI using either interstitial brachytherapy (IB) or stereotactic body radiation therapy (SBRT) with CyberKnife (CK) were retrospectively reviewed. The dosimetric parameters of the target and OARs were compared.
BJR Open
January 2024
Department of Experimental Physics - Medical Physics, Faculty for Physics of the Ludwig-Maximilians-Universität München (LMU Munich), Geschwister-Scholl-Platz 1, München, 80539, Germany.
This review presents and discusses the ways in which artificial intelligence (AI) tools currently intervene, or could potentially intervene in the future, to enhance the diverse tasks involved in the radiotherapy workflow. The radiotherapy framework is presented on 2 different levels for the personalization of the treatment, distinct in tasks and methodologies. The first level is the clinically well-established anatomy-based workflow, known as adaptive radiation therapy.
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