A clinical test and application research of IMRT dose verification system based on patient′s anatomical structure and on-line dosimetry
LIN Hai-lei, HUANG Shao-min, DENG Xiao-wu, JIN Guang-hua, SUN Wen-zhao, YAO Xing-hong, ZHANG Dan-dan, CHEN Li-xin
Department of Radiation Oncology, SUN Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Guangzhou 510060, China. Corresponding author:DENG Xiao-wu, Email:dengxw@mail.sysu.edu.cn
Abstract：Objective To test a three-dimensional dose verification system, which reconstructing dose to anatomy based on modeling and online measurements (RDBMOM), and to evaluate the accuracy and feasibility of its application in clinical intensity-modulated radiotherapy (IMRT) quality assurance. Methods Phantom plans of regular and irregular fields were selected for the testing. All test plans were implemented and the dose distributions were measured using the thimble ion-chamber and two-dimensional ion-chamber array, the accuracy of RDBMOM were then evaluated by comparing the corresponding results. Two practical treated nasopharyngeal carcinoma IMRT plans were verified with RDBMOM and the clinic significancy were valued. Results Compared with measurements of the thimble ion-chamber, deviations of RDBMOM were within 1% in all tested cases except small field of 3 cm×3 cm. The largest deviation of reconstructed dose in IMRT cases was 2.12%. The dose profile reconstructed by RDBMOM coincided with the measurement using two-dimensional ion-chamber array. The γ rates (3%/3 mm) were 94.56%－100%. The RDBMOM verification of IMRT cases shown that the γ rate>99% in total and>98% in planning target volume, deviation in D95<0.4%, but the largest deviations in mean dose of the parotids and lens were 2.97% and 59.58% respectively. Conclusions Accuracy of the tested system satisfies the demand of IMRT dose verification. RDBMOM is able to provide information of volumetric dosimetry and anatomical location of dose error, which is benefit for evaluating the clinical value of verification results.
LIN Hai-lei,HUANG Shao-min,DENG Xiao-wu et al. A clinical test and application research of IMRT dose verification system based on patient′s anatomical structure and on-line dosimetry[J]. Chinese Journal of Radiation Oncology, 2012, 21(3): 271-274.
[1] Hendee WR, Herman MG. Improving patient safety in radiation oncology. Med Phys,2011,38:78-82. [2] Nelms BE, Zhen HM, Tome WA. Per-beam planar IMRT QA passing rates do not predict clinically relevant patient dose errors. Med Phys,2011,38:1037-1043. [3] Chang J, Mageras GS, Chui CS, et al. Relative profile and dose verification of intensity-modulated radiation therapy. Int J Radiat Oncol Biol Phys,2000,47:231-240. [4] Low DA, Harms WB, Mutic S, et al. A technique for the quantitative evaluation of dose distributions. Med Phys,1998,25:656-661.
[5] Low DA, Moran JM, Dempsey JF, et al. Dosimetry tools and techniques for IMRT. Med Phys,2011,38:1313-1338. [6] Kruse JJ. On the insensitivity of single field planar dosimetry to IMRT inaccuracies. Med Phys,2010,37:2516-2524. [7] Li QL, Deng XW, Chen LX, et al. The angular dependence of a 2-dimensional diode array and the feasibility of its application in verifying the composite dose distribution of intensity modulated radiation therapy. Chin J Cancer,2010,29:617-620. [8] Van Dyk J, Barnett RB, Cygler JE, et al. Commissioning and quality assurance of treatment planning computers. Int J Radiat Oncol Biol Phys,1993,26:261-273. [9] Bedford JL, Childs PJ, Hansen VN, et al. Commissioning and quality assurance of the Pinnacle3 radiotherapy treatment planning system for external beam photons. Br J Radiol,2003,76:163-176. [10] International atomic energy agency. IAEA Technical reports series No. 430:commissioning and quality assurance of computerized planning systems for radiation treatment of cancer. Vienna:IAEA,2004.
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