A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)

Sarath Vijayan; Zhenyu Xiong; Stephen Rudin; Daniel R. Bednarek

doi:10.1117/12.2216931

29 March 2016 A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)

Sarath Vijayan, Zhenyu Xiong, Stephen Rudin, Daniel R. Bednarek

Author Affiliations +

Proceedings Volume 9783, Medical Imaging 2016: Physics of Medical Imaging; 97832X (2016) https://doi.org/10.1117/12.2216931
Event: SPIE Medical Imaging, 2016, San Diego, California, United States

Abstract

The skin-dose tracking system (DTS) provides a color-coded illustration of the cumulative skin-dose distribution on a closely-matching 3D graphic of the patient during fluoroscopic interventions in real-time for immediate feedback to the interventionist. The skin-dose tracking utility of DTS has been extended to include cone-beam computed tomography (CBCT) of neurointerventions. While the DTS was developed to track the entrance skin dose including backscatter, a significant part of the dose in CBCT is contributed by exit primary radiation and scatter due to the many overlapping projections during the rotational scan. The variation of backscatter inside and outside the collimated beam was measured with radiochromic film and a curve was fit to obtain a scatter spread function that could be applied in the DTS. Likewise, the exit dose distribution was measured with radiochromic film for a single projection and a correction factor was determined as a function of path length through the head. Both of these sources of skin dose are added for every projection in the CBCT scan to obtain a total dose mapping over the patient graphic. Results show the backscatter to follow a sigmoidal falloff near the edge of the beam, extending outside the beam as far as 8 cm. The exit dose measured for a cylindrical CTDI phantom was nearly 10 % of the entrance peak skin dose for the central ray. The dose mapping performed by the DTS for a CBCT scan was compared to that measured with radiochromic film and a CTDI-head phantom with good agreement.

Citation Download Citation

Sarath Vijayan, Zhenyu Xiong, Stephen Rudin, and Daniel R. Bednarek "A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)", Proc. SPIE 9783, Medical Imaging 2016: Physics of Medical Imaging, 97832X (29 March 2016); https://doi.org/10.1117/12.2216931

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