使用康普顿光谱仪在工作条件下测量临床CT机的绝对能谱。

Measurement of absolute energy spectra from a clinical CT machine under working conditions using a Compton spectrometer.

作者信息

Matscheko G, Carlsson G A

机构信息

Department of Radiation Physics, Faculty of Health Sciences, University of Linköping, Sweden.

出版信息

Phys Med Biol. 1989 Feb;34(2):209-22. doi: 10.1088/0031-9155/34/2/005.

DOI:10.1088/0031-9155/34/2/005

PMID:2928385

Abstract

Absolute measurements of photon energy spectra (keV-1 sr-1 mA-1 s-1) from a clinical CT machine have been performed under normal working conditions (140 mA tube current) using a Compton spectrometer. The inaccuracy of the measured spectra is estimated to be +/- 6%, determined by uncertainties in dead-time corrections and in the parameters of the geometrical set-up. Absorbed doses measured in thermoluminescent LiF dosimeters agree within this uncertainty with calculated ones derived from measured spectra (80 kVp, 120 kVp and 140 kVp) and tabulated mass energy absorption coefficients for LiF. Comparison with tabulated energy spectra from the literature clearly shows the effect of the extremely small anode angle (7 degrees) in the CT machine (15 degrees and 17 degrees for the tabulated energy spectra).

摘要

在正常工作条件下（管电流140 mA），使用康普顿光谱仪对临床CT机的光子能谱（keV⁻¹ sr⁻¹ mA⁻¹ s⁻¹）进行了绝对测量。测量光谱的不准确度估计为±6%，这是由死时间校正和几何设置参数的不确定性决定的。在热释光LiF剂量计中测量的吸收剂量在该不确定性范围内与从测量光谱（80 kVp、120 kVp和140 kVp）以及LiF的表格化质能吸收系数得出的计算值一致。与文献中的表格化能谱进行比较清楚地显示了CT机中极小的阳极角度（7度）的影响（表格化能谱的阳极角度为15度和17度）。