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Tomographic Reconstruction Camera - Clarifying and Visualizing Sources of X-Radiation Using Circular Penumbra Analysis

J Brewer1*, A Nicholson1, R Walsh1, J Holzman1, T Bjarnason1,2,3, (1) University of British Columbia Okanagan, Kelowna, CA, (2) University of British Columbia, Vancouver, CA, (3) Interior Health, Kelowna, CA

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose:
Create a tomographic reconstruction (TR) camera for visualizing sources of x-radiation using less dose than a pinhole camera.

Methods:
When a scene is projected through a disk onto a detector, the detected image can be analyzed by drawing radial lines through the penumbra and taking the derivative, resulting in a sinogram of the original scene. A TR and pinhole camera were made of steel with a circular hole 15 and 0.3 cm, respectively, in diameter cut out of the centre of the camera faces. FA CR plate was placed in the camera, 1.3 cm back from the hole for the TR camera and 29 cm back for the pinhole camera, and an x-ray tube was used as a point source to expose the plate from 4 locations. As a TR calibration step, a different number of exposures were generated from the 4 locations to give different intensities from the point sources of radiation. The penumbra of the resulting disk image was analyzed to reconstruct the original scene. Later, a torso phantom was placed on a fluoroscopy patient support table, with the TR camera 1 m away, and the fluoroscopy system was run until a DAP of 344 µGym² was reached. The TR camera captured X-ray scatter; the penumbra was analyzed and the scatter sources reconstructed.

Results:
Using the TR camera, faithful reproductions of point sources of x-ray radiation, and later scatter, were generated at 5 times less dose than the pinhole camera.

Conclusion:
This work demonstrates that x- radiation point sources can be accurately imaged using circular penumbra tomographic reconstruction.

Download ePoster [PDF]

Keywords

Not Applicable / None Entered.

Taxonomy

IM- X-Ray: Development (new technology and techniques)

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