Influence of cone beam CT (CBCT) scan parameters on size specific dose estimate (SSDE): A Monte Carlo study.

Influence of cone beam CT (CBCT) scan parameters on size specific dose estimate (SSDE): A Monte Carlo study. Phys Med Biol. 2019 Mar 01;: Authors: Abuhaimed A, Martin CJ, Demirkaya O Abstract The CT dose index (CTDI<sub>vol</sub>) is the dosimetric quantity used for multi-slice CT (MSCT) with beams ≤4 cm. Conversion factors (f<sub>size</sub>) based on patient size are applied to CTDI<sub>vol</sub> to adjust for differences in patient size and derive size-specific dose estimates (SSDE) relating to patient dose. The aim of this study is to: (1) investigate use of a similar technique to provide SSDE values for cone beam CT (CBCT) scans, (2) determine whether factors derived for narrow beam MSCT are suitable for CBCT, and (3) investigate the influence of CBCT parameters on f<sub>size</sub> values. Monte Carlo simulations were used to model an on-board imager system integrated into a Varian Truebeam linear accelerator, and to assess doses for imaging. The CTDI<sub>vol</sub> is unsuitable for CBCT dosimetry, thus the assessments were applied to the modification CTDI<sub>IEC</sub>, recommended by the international electrotechnical commission (IEC). Conversion factors (f<sub>size,CBCT</sub>) were derived for CBCT to allow adjustment of values for the absorbed dose in water (AD) averaged over the beam width in the middle of the phantoms. Values of AD were evaluated ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research

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