Proposal for a Simple and Efficient Monthly Quality Management Program Assessing the Consistency of Robotic Image-Guided Small Animal Radiation Systems

Abstract

Modern pre-clinical radiation therapy (RT) research requires high precision and accurate dosimetry to facilitate the translation of research findings into clinical practice. Several systems are available that provide precise delivery and on-board imaging capabilities, highlighting the need for a quality management program (QMP) to ensure consistent and accurate radiation dose delivery. An ongoing, simple, and efficient QMP for image-guided robotic small animal irradiators used in pre-clinical RT research is described. Protocols were developed and implemented to assess the dose output constancy (based on the AAPM TG-61 protocol), cone-beam computed tomography (CBCT) image quality and object representation accuracy (using a custom-designed imaging phantom), CBCT-guided target localization accuracy and consistency of the CBCT-based dose calculation. To facilitate an efficient read-out and limit the user dependence of the QMP data analysis, a semi-automatic image analysis and data representation program was developed using the technical computing software MATLAB. The results of the first six months experience using the suggested QMP for a Small Animal Radiation Research Platform (SARRP) are presented, with data collected on a bi-monthly basis. The dosimetric output constancy was established to be within ±1 %, the consistency of the image resolution was within ±0.2 mm, the accuracy of CBCT-guided target localization was within ±0.5 mm, and dose calculation consistency was within ±2 s (± 3 %) per treatment beam. Based on these results, this simple quality assurance program allows for the detection of inconsistencies in dosimetric or imaging parameters that are beyond the acceptable variability for a reliable and accurate pre-clinical RT system, on a monthly or bi-monthly basis.

Development and implementation of EPID‐based quality assurance tests for the small animal radiation research platform (SARRP)

“…We found that the maximum beam‐targeting displacement for the delivery isocenter (laser intersection) was 1.95 ± 0.04 mm before our SARRP mechanical calibration, which dropped to 0.76 ± 0.09 mm after calibration. This value is consistent with Brodin's value for target localization accuracy of SARRP …”

“…In previous works, Brodin et al. had suggested a methodology to measure the beam‐targeting alignment of the SARRP system . Because of difficulty in acquiring good quality portal images at different gantry angles, Brodin et al.…”

“…Brodin et al. proposed a monthly quality management process for the SARRP system, and Ngwa et al. investigated the use of a mouse‐size metal oxide semiconductor field effect transistor (MOSFET) phantom for QA of the SARRP …”

“…7 Other investigators have proposed QA guidelines for these systems. Brodin et al proposed a monthly quality management process for the SARRP system, 9 and Ngwa et al investigated the use of a mouse-size metal oxide semiconductor field effect transistor (MOSFET) phantom for QA of the SARRP. 10 Although these procedures are quite useful in ensuring the accuracy and consistency of SA-IGRT imaging and treatments, one of the challenges with these quality management approaches is that they rely on dosimeters that require some level of physics expertise and specialized equipment (e.g., phantoms, ion chamber, films, scanner, MOSFET, etc.).…”

Tumour and normal tissue radiobiology in mouse models: how close are mice to mini-humans?

“…Multiple examples exist in the literature of QA regimens for initial commissioning and routine maintenance. [45][46][47] Key elements are QA testing for dose rate constancy, imaging quality and targeting localizations that are performed on a regular basis. More advanced dosimetry techniques for small animal research may be based on using an imaging panel, in analogy with portal dosimetry in RT.…”