Thecal Sac Contouring as a Surrogate for the Cauda Equina and Intracanal Spinal Nerve Roots for Spine Stereotactic Body Radiation Therapy (SBRT): Contour Variability and Recommendations for Safe Practice.

Purpose: To present interobserver variability in thecal sac (TS) delineation based on contours generated by 8 radiation oncologists experienced in spine stereotactic body radiation therapy and to propose contouring recommendations to standardize practice.

Methods And Materials: In the setting of a larger contouring study that reported target volume delineation guidelines specific to sacral metastases, 8 academically based radiation oncologists with dedicated spine stereotactic body radiation therapy programs independently contoured the TS as a surrogate for the cauda equina and intracanal spinal nerve roots. Uniform treatment planning simulation computed tomography datasets fused with T1, T2, and T1 post gadolinium magnetic resonance imaging for each case were distributed to each radiation oncologist.

International consensus recommendations for target volume delineation specific to sacral metastases and spinal stereotactic body radiation therapy (SBRT).

Background And Purpose: To interrogate inter-observer variability in gross tumour volume (GTV) and clinical target volume (CTV) delineation specific to the treatment of sacral metastases with spinal stereotactic body radiation therapy (SBRT) and develop CTV consensus contouring recommendations.

Materials And Methods: Nine specialists with spinal SBRT expertise representing 9 international centres independently contoured the GTV and CTV for 10 clinical cases of metastatic disease within the sacrum. Agreement between physicians was calculated with an expectation minimisation algorithm using simultaneous truth and performance level estimation (STAPLE) and with kappa statistics.

Dose-painted volumetric modulated arc therapy of high-grade glioma using 3,4-dihydroxy-6-[F]fluoro-L-phenylalanine positron emission tomography.

Objective: To determine whether dose painting with volumetric modulated arc therapy for high-grade gliomas using 3,4-dihydroxy-6-[F]fluoro-l-phenylalanine (F-FDOPA) positron emission tomography (PET) could achieve dose-escalated coverage of biological target volumes (BTVs) without increasing the dose to cranial organs at risk (OARs).

Methods: 10 patients with high-grade gliomas underwent CT, MRI, and F-FDOPA PET/CT images for post-operative radiation therapy planning. Two volumetric modulated arc therapy plans were retrospectively generated for each patient: a conventional plan with 60 Gy in 30 fractions to the planning target volume delineated on MRI and a dose-escalated plan with a maximum dose of 80 Gy in 30 fractions to BTVs.

Multi-institutional Randomized Trial Testing the Utility of an Interactive Three-dimensional Contouring Atlas Among Radiation Oncology Residents.

Purpose: The delivery of safe and effective radiation therapy relies on accurate target delineation, particularly in the era of highly conformal treatment techniques. Current contouring resources are fragmented and can be cumbersome to use. The present study reports on the efficacy and usability of a web-based contouring atlas compared with those of existing contouring resources in a randomized trial.

Interhemispheric Difference Images from Postoperative Diffusion Tensor Imaging of Gliomas.

Introduction Determining the full extent of gliomas during radiotherapy planning can be challenging with conventional T1 and T2 magnetic resonance imaging (MRI). The purpose of this study was to develop a method to automatically calculate differences in the fractional anisotropy (FA) and mean diffusivity (MD) values in target volumes obtained with diffusion tensor imaging (DTI) by comparing with values from anatomically homologous voxels on the contralateral side of the brain. Methods Seven patients with a histologically confirmed glioma underwent postoperative radiotherapy planning with 1.

Liver toxicity prediction with stereotactic body radiation therapy: The impact of accounting for fraction size.

Purpose: Current liver SBRT protocols rely on the calculation of "effective volume" without accounting for the biologic effect of fraction size to estimate the risk of liver toxicity, which subsequently defines tumor prescription doses. This study compared effective volume and liver toxicity predictions with and without correction for fraction size.

Methods And Materials: The effective volume was determined for 18 liver SBRT plans with and without biologic normalization using the linear quadratic formula.

High-grade glioma radiation therapy target volumes and patterns of failure obtained from magnetic resonance imaging and 18F-FDOPA positron emission tomography delineations from multiple observers.

Purpose: The objective of this study was to compare recurrent tumor locations after radiation therapy with pretreatment delineations of high-grade gliomas from magnetic resonance imaging (MRI) and 3,4-dihydroxy-6-[(18)F]fluoro-L-phenylalanine ((18)F-FDOPA) positron emission tomography (PET) using contours delineated by multiple observers.

Methods And Materials: Nineteen patients with newly diagnosed high-grade gliomas underwent computed tomography (CT), gadolinium contrast-enhanced MRI, and (18)F-FDOPA PET/CT. The image sets (CT, MRI, and PET/CT) were registered, and 5 observers contoured gross tumor volumes (GTVs) using MRI and PET.

Dose-distance metric that predicts late rectal bleeding in patients receiving radical prostate external-beam radiotherapy.

The relationship between rectal dose distribution and the incidence of late rectal complications following external-beam radiotherapy has been previously studied using dose-volume histograms or dose-surface histograms. However, they do not account for the spatial dose distribution. This study proposes a metric based on both surface dose and distance that can predict the incidence of rectal bleeding in prostate cancer patients treated with radical radiotherapy.

Evaluation of dosimetric consequences of seroma contour variability in accelerated partial breast irradiation using a constructed representative seroma contour.

Purpose: Contouring variability of the seroma can have important implications in the planning and delivery of accelerated partial breast irradiation (APBI). This study aimed to quantify the dosimetric impact of these interobserver and intraobserver contouring variations by construction of a representative seroma contour (RSC).

Methods And Materials: Twenty-one patients with a seroma suitable for APBI underwent four computed tomography (CT) scans: one planning CT and three additional CTs on the first, third, and fifth days of treatment.