Dataset Information

The Importance of Verification CT-QA Scans in Patients Treated with IMPT for Head and Neck Cancers.

ABSTRACT: Purpose:To understand how verification computed tomography-quality assurance (CT-QA) scans influenced clinical decision-making to replan patients with head and neck cancer and identify predictors for replanning to guide intensity-modulated proton therapy (IMPT) clinical practice. Patients and Methods:We performed a quality-improvement study by prospectively collecting data on 160 consecutive patients with head and neck cancer treated using spot-scanning IMPT who underwent weekly verification CT-QA scans. Kaplan-Meier estimates were used to determine the cumulative probability of a replan by week. Predictors for replanning were determined with univariate (UVA) and multivariate (MVA) Cox model hazard ratios (HRs). Logistic regression was used to determine odds ratios (ORs). P??60 Gy equivalent (GyE; relative biologic effectiveness, 1.1) (UVA: HR, 1.99, P?

SUBMITTER: Evans JD

PROVIDER: S-EPMC7574830 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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The Importance of Verification CT-QA Scans in Patients Treated with IMPT for Head and Neck Cancers.

Evans Jaden D JD Harper Riley H RH Petersen Molly M Harmsen William S WS Anand Aman A Hunzeker Ashley A Deiter Noelle C NC Schultz Heather H Jethwa Krishan R KR Lester Scott C SC Routman David M DM Ma Daniel J DJ Garces Yolanda I YI Neben-Wittich Michelle A MA Laack Nadia N NN Beltran Chris J CJ Patel Samir H SH McGee Lisa A LA Rwigema Jean-Claude M JM Mundy Daniel W DW Foote Robert L RL

International journal of particle therapy 20200803 1

<h4>Purpose</h4>To understand how verification computed tomography-quality assurance (CT-QA) scans influenced clinical decision-making to replan patients with head and neck cancer and identify predictors for replanning to guide intensity-modulated proton therapy (IMPT) clinical practice.<h4>Patients and methods</h4>We performed a quality-improvement study by prospectively collecting data on 160 consecutive patients with head and neck cancer treated using spot-scanning IMPT who underwent weekly v ...[more]

PMID: 33094135

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Project description:PurposeThe purpose of this paper was to design, manufacture, and evaluate a tissue equivalent, dual magnetic resonance/computed tomography (MR/CT) visible anthropomorphic head and neck (H&N) phantom. This phantom was specially designed as an end-to-end quality assurance (QA) tool for MR imaging guided radiotherapy (MRIgRT) systems participating in NCI-sponsored clinical trials.MethodThe MRIgRT H&N phantom was constructed using a water-fillable acrylic shell and a custom insert that mimics an organ at risk (OAR) and target structures. The insert consists of a primary and secondary planning target volume (PTV) manufactured of a synthetic Clear Ballistic gel, an acrylic OAR and surrounding tissue fabricated using melted Superflab. Radiochromic EBT3 film and thermoluminescent detectors (TLDs) were used to measure the dose distribution and absolute dose, respectively. The phantom was evaluated by conducting an end-to-end test that included: imaging on a GE Lightspeed CT simulator, planning on Monaco treatment planning software (TPS), verifying treatment setup with MR, and irradiating on Elekta's 1.5 T Unity MR linac system. The phantom was irradiated three times using the same plan to determine reproducibility. Three institutions, equipped with either ViewRay MRIdian 60 Co or ViewRay MRIdian Linac, were used to conduct a feasibility study by performing independent end-to-end studies. Thermoluminescent detectors were evaluated in both reproducibility and feasibility studies by comparing ratios of measured TLD to reported TPS calculated values. Radiochromic film was used to compare measured planar dose distributions to expected TPS distributions. Film was evaluated by using an in-house gamma analysis software to measure the discrepancies between film and TPS.ResultsThe MRIgRT H&N phantom on the Unity system resulted in reproducible TLD doses (SD < 1.5%). The measured TLD to calculated dose ratios for the Unity system ranged from 0.94 to 0.98. The Viewray dose result comparisons had a larger range (0.95-1.03) but these depended on the TPS dose calculations from each site. Using a 7%/4 mm gamma analysis, Viewray institutions had average axial and sagittal passing rates of 97.3% and 96.2% and the Unity system had average passing rates of 97.8% and 89.7%, respectively. All of the results were within the Imaging and Radiation Oncology Core in Houston (IROC-Houston) standard credentialing criteria of 7% on TLDs, and >85% of pixels passing gamma analysis using 7%/4 mm on films.ConclusionsAn MRIgRT H&N phantom that is tissue equivalent and visible on both CT and MR was developed. The results from initial reproducibility and feasibility testing of the MRIgRT H&N phantom using the tested MGIgRT systems suggests the phantom's potential utility as a credentialing tool for NCI-clinical trials.

Dataset Information

The Importance of Verification CT-QA Scans in Patients Treated with IMPT for Head and Neck Cancers.

Publications

The Importance of Verification CT-QA Scans in Patients Treated with IMPT for Head and Neck Cancers.

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