A new cone-beam computed tomography dosimetry method providing optimal measurement positions: A Monte Carlo study

Tomonobu Haba, Keisuke Yasui, Yasunori Saito, Masanao Kobayashi, Shuji Koyama

研究成果: Article査読

抄録

Purpose: The conventional weighted computed tomography dose index (CTDIw) may not be suitable for cone-beam computed tomography (CBCT) dosimetry because a cross-sectional dose distribution is angularly inhomogeneous owing to partial angle irradiations. This study was conducted to develop a new dose metric (f(0)CBw) for CBCT dosimetry to determine a more accurate average dose in the central cross-sectional plane of a cylindrical phantom using Monte Carlo simulations. Methods: First, cross-sectional dose distributions of cylindrical polymethyl methacrylate phantoms over a wide range of phantom diameters (8–40 cm) were calculated for various CBCT scan protocols. Then, by obtaining linear least-squares fits of the full datasets of the cross-sectional dose distributions, the optimal radial positions, which represented measurement positions for the average phantom dose, were determined. Finally, the f(0)CBw method was developed by averaging point doses at the optimal radial positions of the phantoms. To demonstrate its validity, the relative differences between the average doses and each dose index value were estimated for the devised f(0)CBw, conventional CTDIw, and Haba's CTDIw methods, respectively. Results: The relative differences between the average doses and each dose index value were within 4.1%, 16.7%, and 11.9% for the devised, conventional CTDIw, and Haba's CTDIw methods, respectively. Conclusions: The devised f(0)CBw value was calculated by averaging four “point doses” at 90° intervals and the optimal radial positions of the cylindrical phantom. The devised method can estimate the average dose more accurately than the previously developed CTDIw methods for CBCT dosimetry.

本文言語English
ページ(範囲)130-140
ページ数11
ジャーナルPhysica Medica
81
DOI
出版ステータスPublished - 01-2021

All Science Journal Classification (ASJC) codes

  • 生物理学
  • 放射線学、核医学およびイメージング
  • 物理学および天文学(全般)

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