Laser cone beam computed tomography scanner geometry for large volume 3D dosimetry

7th International Conference on 3D Radiation Dosimetry

Jordan, K.J.^1,2 ; Turnbull, D.^1 ; Batista, J.J.^1,2

London Regional Cancer Program, London Health Sciences Centre, Western University, London, ON, Canada^1

Department of Medical Biophysics, Western University, London, ON, Canada^2

关键词: Cone-beam computed tomography;    High dynamic range;    Low power laser beams;    Photo multiplier tube;    Refractive index matching;    Scanner geometry;    Transmitted beams;    Transparent objects;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/444/1/012062/pdf
DOI  :  10.1088/1742-6596/444/1/012062

来源: IOP

【 摘 要 】

A new scanner geometry for fast optical cone-beam computed tomography is reported. The system consists of a low power laser beam, raster scanned, under computer control, through a transparent object in a refractive index matching aquarium. The transmitted beam is scattered from a diffuser screen and detected by a photomultiplier tube. Modest stray light is present in the projection images since only a single ray is present in the object during measurement and there is no imaging optics to introduce further stray light in the form of glare. A scan time of 30 minutes was required for 512 projections with a field of view of 12 x 18 cm. Initial performance from scanning a 15 cm diameter jar with black solutions is presented. Averaged reconstruction coefficients are within 2% along the height of the jar and within the central 85% of diameter, due to the index mismatch of the jar. Agreement with spectrometer measurements was better than 0.5% for a minimum transmission of 4% and within 4% for a dark, 0.1% transmission sample. This geometry's advantages include high dynamic range and low cost of scaling to larger (>15 cm) fields of view.