Room: AAPM ePoster Library
Purpose: To determine the feasibility of using air scintillation images taken with an on-board electron multiplying CCD (EMCCD) camera for daily dose output checks and alignment of a small animal cabinet x-ray system to improve the quality of preclinical studies.
Methods: Measurements were performed using a X-Rad SmART (Precision X-Ray Inc., North Bradford, CT) cabinet irradiatior equipped with an Andor EDCCD camera (Oxford Instruments, Abingdon, UK). Air scintillation images were acquired during irradiation with 225 kVp x-rays at various mA settings with a 25 mm square collimator. Measurements consisted of acquiring 20 images, each with an exposure time of 1 s. To determine the relationship between scintillation and output, images were acquired at mA settings ranging from 5 mA to 20 mA. Images were median filtered to remove unwanted signal from scattered x-rays. The sum of a fixed ROI in the high signal region, chosen based on the 20 mA image, was calculated. As a test of radiation and laser coincidence, an optical image of the alignment lasers was taken and overlaid on a scintillation image. The FWHM of the radiation field was used to determine the center of the radiation field across the plane containing the intersection of the setup lasers.
Results: A linear relationship between the integral scintillation signal and mA was observed. The center of the radiation field was determined to be 2.25 mm away from the intersection of the setup lasers.
Conclusion: Air scintillation measurements have the potential to provide an easy tool for dose output monitoring of small animal x-ray platforms. In addition, air scintillation images and setup lasers can be used to determine radiation-laser isocenter coincidence.