一种利用伽玛刀单次剂量分布对放射变色胶片进行有效校准的技术。

An effective calibration technique for radiochromic films using a single-shot dose distribution in Gamma Knife(®).

作者信息

Chung Jae Pil, Oh Se Woon, Seong Young Min, Chun Kook Jin, Chung Hyun-Tai

机构信息

Department of Medical Physics, Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejon 34113, Republic of Korea; Center for Ionizing Radiation, Division of Metrology for Quality of Life, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Yuseong-Gu, Daejon 34113, Republic of Korea.

Center for Ionizing Radiation, Division of Metrology for Quality of Life, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Yuseong-Gu, Daejon 34113, Republic of Korea.

出版信息

Phys Med. 2016 Feb;32(2):368-78. doi: 10.1016/j.ejmp.2016.02.001. Epub 2016 Feb 15.

DOI:10.1016/j.ejmp.2016.02.001

PMID:26898105

Abstract

PURPOSE

A method of calibrating radiochromic films for Gamma Knife(®) (GK) dosimetry was developed. The applicability and accuracy of the new method were examined.

METHODS

The dose distribution for a sixteen millimeter single-shot from a GK was built using a reference film that was calibrated using the conventional multi-film calibration (MFC) method. Another film, the test film, from a different set of films was irradiated under the same conditions as the reference film. The calibration curve for the second set of films was obtained by assigning the dose distribution of the reference film to the optical density of the test film, point by point. To assess the accuracy of this single-film calibration (SFC) method, differences between gamma index pass rates (GIPRs) were calculated.

RESULTS

The SFC curves were successfully obtained with estimated errors of 1.46%. GIPRs obtained with the SFC method for films irradiated using a single-shot showed differences less than one percentage point when dose difference criterion (ΔD) was 2% and the distance to agreement criterion (Δd) was 1 mm. The GIPRs of the SFC method when the films were irradiated following a virtual target treatment plan were consistent with the GIPRs of the MFC method, with differences of less than 0.2 percentage points for ΔD = 1% and Δd = 1 mm.

CONCLUSION

The accuracy of the SFC method is comparable to that of conventional multi-film calibration method for GK film dosimetry.

摘要

目的

开发一种用于伽玛刀（®）剂量测定的放射变色胶片校准方法。研究了该新方法的适用性和准确性。

方法

使用通过传统多胶片校准（MFC）方法校准的参考胶片构建伽玛刀16毫米单次照射的剂量分布。另一张胶片，即测试胶片，来自不同的胶片组，在与参考胶片相同的条件下进行照射。通过将参考胶片的剂量分布逐点分配给测试胶片的光学密度，获得第二组胶片的校准曲线。为了评估这种单胶片校准（SFC）方法的准确性，计算了伽马指数通过率（GIPR）之间的差异。

结果

成功获得了SFC曲线，估计误差为1.46%。当剂量差异标准（ΔD）为2%且距离一致性标准（Δd）为1毫米时，使用SFC方法对单次照射的胶片获得的GIPR差异小于1个百分点。当按照虚拟靶区治疗计划照射胶片时，SFC方法的GIPR与MFC方法的GIPR一致，对于ΔD = 1%和Δd = 1毫米，差异小于0.2个百分点。