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Quality assurance in the CHART clinical trial
E G Aird1, C Williams, G T Mott
1Marie Curie Research Wing for Oncology, Mount Vernon Hospital, Northwood, Middlesex, UK.
Summary
Quality assurance for continuous hyperfractionated accelerated radiotherapy (CHART) trials revealed most centers met technical standards. However, some centers showed weaknesses in flatness, wedge factor, and energy, impacting treatment accuracy.
Area of Science:
- Radiation Oncology
- Clinical Trial Quality Assurance
- Radiotherapy Physics
Background:
- The clinical trial of Continuous Hyperfractionated Accelerated Radiotherapy (CHART) necessitated a robust quality assurance (QA) program.
- Ensuring consistency and accuracy in treatment planning and delivery is critical for the success of complex radiotherapy protocols.
- This paper focuses on the technical aspects of the QA program implemented for the CHART trial.
Purpose of the Study:
- To evaluate the technical performance of radiotherapy equipment and procedures across multiple participating centers in the CHART trial.
- To identify specific areas of strength and weakness in treatment planning and delivery within the participating centers.
- To assess the impact of technical parameters on the accuracy of radiation dosimetry and treatment delivery.
Main Methods:
- Conducted site visits to 13 participating centers, including repeat visits to some, to assess technical aspects of radiotherapy.
- Performed a series of tests on linear accelerators, focusing on mechanical/optical scales, field size, flatness, and symmetry.
- Evaluated dosimetry parameters including output, wedge factor, beam energy, and performed phantom measurements against center-calculated plans.
- Assessed mechanical and optical scales and indicators on simulators.
Main Results:
- Most participating centers operated within established tolerances for the majority of tested parameters.
- Identified specific areas of weakness in flatness, wedge factor, and beam energy at some centers.
- Observed a significant spread in phantom measurement results (-7% to +6% difference between calculated and measured values) after accounting for output variations, likely linked to identified weaknesses.
Conclusions:
- While most technical aspects of radiotherapy delivery in the CHART trial were within acceptable limits, specific parameters require attention.
- Inconsistencies in flatness, wedge factor, and beam energy were identified as potential contributors to dosimetry variations.
- Addressing these technical weaknesses is crucial for improving the precision and reliability of continuous hyperfractionated accelerated radiotherapy.