研究目的
To demonstrate a method for acquiring variable resolution, photon beam pro?le data using a commercially available ion chamber array to increase efficiency in linear accelerator commissioning and quality assurance measurements.
研究成果
The IC‐Pro?ler? array can efficiently acquire photon beam profiles for field sizes from 5 × 5 to 25 × 25 cm2 within 2%/2 mm agreement to water tank scanning system data, offering a fourfold reduction in MU for scans larger than 15 × 15 cm2. However, it does not replace the need for water tank scans at commissioning due to limitations in achieving >90% pass rate at 1%/1 mm tolerance.
研究不足
The method did not achieve >90% pass rate at 1%/1 mm tolerance compared to 3D water tank data, suggesting that a water tank scan system is still required for commissioning. The technique is not recommended for small field sizes <4 × 4 cm2 at 1%/1 mm criteria or for depth dose measurements due to beam hardening artifacts.
1:Experimental Design and Method Selection:
Utilized a commercially available ion chamber array (IC‐Pro?ler?) to acquire photon beam profiles at various field sizes and depths in solid water. Composite profiles were generated by combining discrete point measurements made at multiple couch positions.
2:Sample Selection and Data Sources:
Field sizes of 2 × 2, 5 × 5, 10 × 10, 15 × 15, 25 × 25, and 40 × 40 cm2 were acquired at depths of dmax, 5 cm, and 10 cm in solid water for 6 and 23 MV photon beams.
3:List of Experimental Equipment and Materials:
IC‐Pro?ler? (Sun Nuclear), TrueBeam? linac (Varian), solid water slabs (CIRS), and a custom Python? script for data reconstruction.
4:Experimental Procedures and Operational Workflow:
The IC‐Pro?ler? was placed on the couch atop solid water for backscatter and under varying thicknesses of solid water to achieve different depths. Data were acquired at multiple couch positions to increase data density.
5:Data Analysis Methods:
Gamma analysis was used to compare the IC‐Pro?ler? data to water tank scan data at 1%/1 mm and 2%/2 mm tolerance levels.
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