Researcher(s)
- Nicole Wang, Biochemistry, University of Delaware
Faculty Mentor(s)
- Hank Chen, Radiation Oncology, ChristianaCare
- Laura Doyle, Radiation Oncology, ChristianaCare
Abstract
Background
Radiation therapy is a form of cancer treatment that uses precise control of ionizing radiation to damage malignant cancer cells. New external beam techniques, including intensity-modulated radiation therapy (IMRT) and volumetric arc therapy (VMAT), have led to more conformal methods of treatment, but mistakes in dose delivery can have catastrophic consequences. Quality assurance (QA) tests verifying dose have become an essential part of practice to reduce the likelihood of delivery errors. In this study, two common dose verification methods – ArcCHECK phantom QA and optically stimulated luminescence dosimeter (OSLD) readings – are explored for effectiveness in IMRT/VMAT safety assurance.
Methods
The ArcCHECK is a cylindrical detector array used to verify machine dose delivery for IMRT/VMAT patient plans. Its associated software, SNCPatient, compares measured dose to theoretical plans using gamma analysis, demonstrating treatment confidence in quantified similarities of >90%. OSLDs are small chips that provide surface dose measurements and have been noted to produce more accurate measurements (±5.5%) than older methods. After receiving dose, OSLDs are read by a microSTARii reader and must be converted back to dose units through use of a calibration curve.
Results
In a 6-month (1/17/23 – 7/17/23) retrospective analysis of QA data, 98.5% of first time ArcCHECK plans (N = 609) passed the 90% gamma analysis threshold. In the same period, OSLDs receiving direct Rx dose (N = 30) reported reception of an average of 99.01 (± 3.72) % of original prescription. Results also displayed that readings were able to be converted by a single non-linear calibration curve independent of energy (±2%), increasing efficiency of measurement.
Conclusion
The study recommends continued use of ArcCHECK and OSLD verification. Both devices are shown to provide ChristianaCare with efficient methods of QA, supporting dose verification checks and peer review processes to ensure safe radiation delivery for patients.