评估在假设乳腺癌放疗情况下锥形束 CT 中伪影位置与 CT 剂量指数的关系。

Evaluation of the relationship between phantom position and computed tomography dose index in cone beam computed tomography when assuming breast irradiation.

机构信息

Department of Radiology, Takaoka City Hospital, Takaoka, Toyama, Japan.

Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan.

出版信息

J Appl Clin Med Phys. 2021 Jun;22(6):262-267. doi: 10.1002/acm2.13282. Epub 2021 May 28.

DOI:10.1002/acm2.13282

PMID:34048143

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8200449/

Abstract

This study aims to investigate the influence of the phantom position on weighted computed tomography dose index (CTDI ) in cone beam computed tomography (CBCT) when assuming breast irradiation. Computed tomography dose index (CTDI) was measured by the x-ray volume imaging of CBCT using parameters for image-guided radiation therapy (IGRT) in right breast irradiation. The measurement points of CTDI ranged from 0 (center) to 16 cm in the right-left (RL) direction, and from 0 (center) to 7.5 cm in the anterior-posterior (AP) direction, which assumed right breast irradiation. A nonuniform change exists in the relative value of CTDI when the phantom deviated from the isocenter of CBCT. The CTDI was ~30% lower compared with the value at the isocenter of CBCT when the phantom deviated 7.5 and 16 cm at the AP and RL directions, respectively. This study confirmed the influence of the phantom position on the CTDI values of CBCT. The CTDI measured at the isocenter of CBCT overestimates that measured at the irradiation center of the breast.

摘要

本研究旨在探讨在假设乳腺癌放射治疗时，体模位置对锥形束 CT（CBCT）加权 CT 剂量指数（CTDI）的影响。采用图像引导放射治疗（IGRT）的 CBCT 射线容积成像来测量 CT 剂量指数（CTDI）。在右侧乳腺照射时，CTDI 的测量点范围从 0（中心）到 16cm 的左右（RL）方向，以及从 0（中心）到 7.5cm 的前后（AP）方向。当体模偏离 CBCT 的等中心时，CTDI 的相对值存在不均匀变化。当体模在 AP 和 RL 方向上分别偏离 7.5cm 和 16cm 时，CTDI 比 CBCT 等中心处的值低约 30%。本研究证实了体模位置对 CBCT 的 CTDI 值的影响。在 CBCT 的等中心处测量的 CTDI 高估了在乳腺照射中心处测量的 CTDI。