Assessment of volumetric absorbed dose for mobile fluoroscopic 3D image acquisition.

Assessment of volumetric absorbed dose for mobile fluoroscopic 3D image acquisition.
J Appl Clin Med Phys. 2017 Jun 06;:
Authors: Leon S
Abstract
Mobile fluoroscopy (c-arm) units offering 3D image reconstruction are becoming more common in surgical settings. Although these images are "CT-like" and sometimes replace the postoperative CT, the acquisition is technically very different from a traditional CT acquisition. Dose assessment is complicated by a large beam width, automatic exposure rate control, and a rotation of less than 360°. The purpose of this work was to explore the impact of these factors on the volumetric dose calculation and to provide practical recommendations for clinical physicists assessing dose from these units using commonly available equipment. CTDIW was calculated using the IAEA method for dosimetry of wide beams and compared to scans of the 32-cm CTDI phantom using the full beam width and a 20-mm collimated beam width. The impact of the partial rotation on the CTDIW calculation was assessed by acquiring measurements at four and twelve positions on the phantom periphery. For the system tested, the CTDIW was calculated to be 16.1 mGy using the IAEA method with default clinical protocol. Results showed that measuring CTDIW with the full beam width or a collimated beam width alone resulted in CTDI values of 19.0 mGy and 19.5 mGy, respectively. Using four peripheral measurements instead of 12 resulted in a diff...

Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Leon S Tags: J Appl Clin Med Phys Source Type: research