DOI

https://doi.org/10.25772/JNKF-S777

Defense Date

2023

Document Type

Thesis

Degree Name

Master of Science

Department

Medical Physics

First Advisor

Siyong Kim

Second Advisor

William Song

Third Advisor

Frank Corwin

Fourth Advisor

Taeho Kim

Abstract

Purpose: To develop and incorporate a QA (quality assurance) program for a Canon Galan 3 tesla MR Simulator for applications in radiation therapy.

Methods and materials: The QA program was centered around tests performed with three separate levels of frequency. The daily QA procedure consisted of scanning a vendor provided daily QA cube phantom that measures basic performance parameters. Additionally, a series of basic safety check were performed. The monthly QA procedure consisted of several tests, including scanning the ACR MRI large accreditation phantom and manually performing its corresponding image quality tests. Scanning the MagPhan RT for its detailed geometric distortion analysis capabilities. Scanning the CaliberMR diffusion phantom for DWI QA. Performing a series of basic mechanical checks on the positional accuracy of the patient couch and external LAP laser positioning system. And outsourcing coil QA to a vendor service engineer who utilized a vendor analysis method. The annual QA tests consisted of an abbreviated version of the ACR image quality tests, along with an ACR table position accuracy test that was also performed on the ACR MRI large accreditation phantom. Further tests include a magnetic field homogeneity test, an evaluation of the complete clinical stock of RF coils, and a retroactive analysis of center frequency using results from the daily QA cube phantom. Additionally, the external laser offset from the isocenter was also verified using the AQUARIUS MRI phantom, monitor QC was performed based on the set of ACR advised SMPTE tests, and the ACR MRI accreditation visual checklist was filled out. Scanner manual and automatic transmit gain calculations were compared using the method outlined in AAPM report 100. All acquired images were examined for the presence of artifacts. Lastly, a qualified medical physicist performed a review of the facility’s MR safety program.

Results: Daily QA has enabled long term tracking of basic performance parameters. Percent SNR experienced an initial drop during December 2021 before stabilizing for the remainder of project. Other basic performance parameters such RF level, helium level, and receiver gain maintained consistency with minor fluctuations occurring day to day. Center frequency remained at 123.196MHz for most of the project duration. Monthly QA and annual QA test protocols were successfully adopted and incorporated into the ongoing quality assurance effort.

Conclusions: This project has established a foundational quality assurance program that can be adjusted to meet the evolving needs of VCU’s department of radiation oncology.

Keywords: Quality Assurance (QA), Magnetic Resonance Simulator (MR-SIM), Phantom

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

5-9-2023

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