Python Software-Guided Small Animal Precision Irradiator Quality Assurance Procedure for Improved Efficacy In Preclinical Research
Abstract
Purpose
Routine and pre-treatment clinical irradiator quality assurance (QA) is vital for ensuring safe, accurate, and reproducible patient care. A primary factor limiting statistical significance in preclinical research is the lack of reproducibility, mainly due to unestablished small animal (SA) irradiator QA programs. Presented is a comprehensive Klio platform to guide the user through, and track, SmART+ irradiator QA procedures and data, incorporating AAPM Task Group 61 (TG-61) dosimetric components.
Methods
Klio is a user-friendly browser-based QA system used to create a guide and inventory for both clinical and preclinical QA, allowing the user to track performance over time and make the required corrections. To ensure consistent alignment to system isocenter, tube, laser, stage, and Winston-Lutz (WL) map alignment calibration is employed. To account for system flex due to gravity, projection map calibration is used. For accurate dose delivery to specimens, output constancy checks are executed, including monthly ion chamber absolute dose measurements (Mraw), annual half-value layer (HVL) copper shim measurements, and annual end effect (∆T) measurements to account for generator delay. Water vial measurements evaluate the dynamic range, allowing recalibration of CT imager presets. Visual examinations ensure integrity of filters, collimators, and safety mechanisms.
Results
Upon QA completion, absolute reference dosimetry measurements and correction factors are calculated from inputted data. Temperature-pressure correction (TTP), ion collection efficiency (Pion), electrometer polarity correction (Ppol), and electrometer measurement (Pelec) provide corrected readings. Backscatter factor (Bw) is calculated by trilinear interpolation of 3D precomputed table of Bw at various distances and HVLs. In addition to providing historical comparisons for WL and projection maps, the changes in HVL, Ppol, Pelec, Bw, TTP, Mraw, and ∆T since the previous QA entry are presented.
Conclusion
Being able to routinely correct for inconsistencies and track changes in SA-irradiator performance allows for improved reproducibility and accuracy in preclinical research.