Feasibility of a High-Resolution CMOS 2D Detector Array As a Film Alternative for IMRT Commissioning
Abstract
Purpose
To evaluate a high-resolution CMOS 2D detector array (myQA SRS, IBA GmbH, Germany) as an efficient alternative to radiochromic films (RCF) for IMRT commissioning.
Methods
A basket of 5 IMRT plans representing the institution’s current IMRT practice was selected, including paraspinal SBRT, conventional lung, and head and neck quadshot cases. A total of 16 fields, reflecting the range of complexity, were chosen from the basket for delivery on Varian TrueBeam and Ethos linear accelerators (Varian, Palo Alto, CA) using 6X and 6FFF photon beams. Dose measurements were performed in a solid water phantom with the detector plane at 5 cm depth (gantry 0°, SAD 100 cm). For each field, myQA SRS measurements were compared with EBT4 RCF (Ashland, Wilmington, DE), which served as the benchmark method for commissioning. Global gamma (γ) analysis was performed using 2%/1 mm and 1%/1 mm criteria with a 10% low-dose threshold. Dose agreement was assessed as the mean percent dose difference relative to the average dose within a region-of-interest defined by 10% of the film dose maximum.
Results
Across all 16 evaluated fields, the mean γ passing rate was 99.43% ± 0.62% using 2%/1 mm criteria and 97.33% ± 2.30% using 1%/1 mm criteria. The mean dose difference was -0.13% ± 0.81%.
Conclusion
The high-resolution CMOS 2D detector array demonstrated dosimetric performance comparable to radiochromic films for IMRT measurements in solid water at 5 cm depth. Strong dosimetric agreement across both stringent γ criteria and dose-difference metrics, along with reduced processing and analysis complexity relative to film dosimetry, supports the use of myQA SRS as a practical and efficient alternative to radiochromic films for IMRT commissioning.