基于器官的管电流调制降低 CT 扫描眼球剂量的蒙特卡罗模拟
Monte Carlo simulation of eye lens dose reduction from CT scan using organ based tube current modulation.
机构信息
Institute of Radiation Medicine, Fudan University, 200032 Shanghai, China.
Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York 10065, NY, USA.
出版信息
Phys Med. 2018 Apr;48:72-75. doi: 10.1016/j.ejmp.2018.03.011. Epub 2018 Apr 6.
PURPOSE
To investigate lens dose reduction with organ based tube current modulation (TCM) using the Monte Carlo method.
METHODS
To calculate lens dose with organ based TCM, 36 pairs of X-ray sources with bowtie filters were placed around the patient head using a projection angle interval of 10° for one rotation of Computed Tomography (CT). Each projection was simulated respectively. Both voxelized and stylized eye models and Chinese reference male phantoms were used in the simulation, and tube voltages 80, 100, 120 and 140 kVp were used.
RESULTS
Dose differences between two eye models were less than 20%, but large variations were observed among dose results from different projections of all tube voltages investigated. Dose results from 0° (AP) directions were 60 times greater than those from 180° (PA) directions, which enables organ based TCM reduce lens doses by more than 47%.
CONCLUSIONS
Organ based TCM may be used to reduce lens doses. Stylized eye models are more anatomically realistic compared with voxelized eye models and are more reliable for dose evaluation.
目的
使用蒙特卡罗方法研究基于器官的管电流调制（TCM）对晶状体剂量的降低作用。
方法
为了用基于器官的 TCM 计算晶状体剂量，使用带有蝶形滤波器的 36 对 X 射线源，围绕患者头部以 10°的投影角间隔进行一次 CT 旋转。分别对每个投影进行模拟。模拟使用了体素化和简化的眼睛模型以及中国参考男性体模，并使用了管电压 80、100、120 和 140 kVp。
结果
两种眼睛模型之间的剂量差异小于 20%，但在所有研究管电压的不同投影中，剂量结果存在很大差异。0°（AP）方向的剂量结果比 180°（PA）方向的剂量结果大 60 倍，这使得基于器官的 TCM 能够将晶状体剂量降低超过 47%。
结论
基于器官的 TCM 可能用于降低晶状体剂量。与体素化眼睛模型相比，简化的眼睛模型更具有解剖学真实性，更可靠用于剂量评估。
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