Ionization chamber dosimetry based on 60Co absorbed dose to water calibration for diagnostic kilovoltage x-ray beams
Ionization chamber dosimetry based on 60Co absorbed dose to water calibration for diagnostic kilovoltage x-ray beams
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基于 60Co 吸收剂量对水校准的电离室剂量测定，用于诊断千伏 X 射线束
DOI：
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发表时间：
2018
影响因子：
3.5
通讯作者：
Suzuna Umeno
中科院分区：
文献类型：
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作者：
F. Araki;T. Ohno;Suzuna Umeno
这项研究的目的是发展一种新的电离室剂量学公式，用于诊断千伏X射线束，基于60Co吸收剂量-水校准系数。为了验证新的室剂量学，使用SpekCalc程序计算了39个千伏x射线的注量谱，分别为1.4kVp-8.5kVp和50-137.6 mm的管电压。我们使用这些光谱在参考几何设置(水中深度 = 1 cm，场大小 = 20 × 20 cm)下，计算了PTW 30013 Farmer®电离室中千伏x射线束Qx到60Co束的光束质量转换因子。利用和得到了千伏X射线对水的吸收剂量。同时，利用蒙特卡罗计算的39个X射线通量谱的修正因子Cf(对应于AAPM Tg-61)，获得了基于空气比释动能校准系数Nk的水面剂量。通过比较基于39x射线通量谱的水面剂量和基于NK的水面剂量，验证了基于的吸收剂量。利用蒙特卡罗方法计算的深度剂量百分比，得到了基于的水面剂量。对于1.48.5 mm的Al-HVL，范围为0.884-0.956，CF范围为1.264-1.663。除1.4和1.5 mm的Al-HUL外，基于x射线通量谱的水面剂量平均比基于NK的高1.0%，1%在其不确定范围内。因此，可以使用以Nk为基础的吸收剂量-水量值来代替Nk。有了新的室剂量学，室读数可以很容易地转换为使用和计算的吸收剂量。
The purpose of this study was to develop a new ionization chamber dosimetry formalism for diagnostic kilovoltage x-ray beams based on a 60Co absorbed dose-to-water calibration coefficient . To validate the new chamber dosimetry, 39 fluence spectra of kilovoltage x-rays were calculated, using a SpekCalc program, for Al half-value-layer (Al-HVL) values of 1.4–8.5 mm and tube voltages of 50–137.6 kVp. We used these spectra to calculate the beam quality conversion factor for kilovoltage x-ray beams Qx to a 60Co beam for a PTW 30013 Farmer® ionization chamber in a reference geometrical setup (depth = 1 cm in water, field size = 20 × 20 cm2). The absorbed dose to water for kilovoltage x-rays was obtained using and . Meanwhile, the water surface dose based on the air kerma calibration coefficient NK was obtained using a Monte Carlo-calculated correction factor CF (corresponding to in AAPM TG-61) for the 39 x-ray fluence spectra. The absorbed dose based on was validated by comparing the water surface dose for the 39 x-ray fluence spectra with the water surface dose based on NK. The water surface dose based on was obtained using Monte Carlo-calculated percentage depth doses. For Al-HVL ranging from 1.4 to 8.5 mm, ranged from 0.884 to 0.956 and CF ranged from 1.264 to 1.663. The water surface dose based on for the x-ray fluence spectra was 1.0% higher on average than that based on NK, except for Al-HVLs of 1.4 and 1.5 mm and 1% was within their uncertainty ranges. Therefore, it is possible to use the absorbed dose-to-water value based on instead of on NK. With the new chamber dosimetry, the chamber reading can be easily converted to the absorbed dose using and the calculated .
千伏 X 射线束的质能吸收系数和反向散射系数比。
影响因子：
3.5
作者：
Ma,CM;Seuntjens,JP
通讯作者：
Seuntjens,JP