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3-D Commissioning for An Image-Guided Small Animal Micro-Irradiation Platform

X Qian

X Qian1*, J Admovics2, C Wuu3, (1) Columbia University, New York, NY, (2) Rider University, Lawrenceville, NJ, (3) Columbia University, New York, NY

SU-E-J-7 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: In a high resolution image-guided small animal micro-irradiation platform, the mouse stage rotation for cone beam CT imaging is perpendicular to the gantry rotation for sub-millimeter radiation delivery. As such, a 3-D dosimeter, PRESAGE, can provide an excellent tool for verifying both imaging and irradiation coordinates in one system.

Methods:The study was done by using PRESAGE dosimeters and optical scanner. In the small animal platform, both of the mouse stage and the gantry can rotate 360°. Isocentricity and coincidence of the mouse stage and gantry rotations were evaluated with starshots. A dosimeter was placed at the isocenter approximately on the mouse stage. Firstly, the gantry moved to 90° in the irradiation coordinate. The mouse stage rotated 360° while the x-ray was delivered to the dosimeter at certain angles, then both of the gantry and mouse stage moved back to home position. Secondly, the gantry rotated 360° to deliver micro beams to the dosimeter at certain angles. Thirdly, steps one and two were repeated 3 times using 3 dosimeters to determine short-term reproducibility. Finally, dosimeters were canned using an optical scanner to get results. Dosimetric measurements were also performed.

Results:The gantry isocentricity is 1.09 ± 0.15 mm and the mouse stage rotation isocentricity is about 1.1 ± 0.15 mm. Agreement between the measured isocenters of irradiation and imaging coordinates was determined using each starshots from dosimeters. The short-term reproducibility test yielded 0.5 ± 0.1 mm between the imaging isocenter and the irradiation isocenter, with a maximum displacement of 0.8 mm. The rest results will be presented.

Conclusion:The 3-D PRESAGE dosimeter can be very useful in precise verification of targeting for a small animal irradiation research. In addition, a single PRESAGE dosimeter can provide 3-D information in both geometric and dosimetric uncertainty, which is crucial for translational studies.

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