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Study of different dose calculation algorithms for the phantom of metallic implants
Lin Tao, Ni Xinye, Gao Liugang, Sui Jiangfeng, Xie Kai, Chang Shuquan
Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China (Lin Tao,Chang Shuquan) Department of Radiation Oncology,Changzhou No.2 People′s Hospital,Nanjing Medical University,Changzhou 213003,China (Lin Tao,Ni Xinye,Gao Liugang,Sui Jiangfeng,Xie Kai)
AbstractObjective To compare the dose difference between the 12-bit and 16-bit CT images containing metallic implants calculated by different algorithms. Methods The titanium alloy rod was inserted into the phantom and subject to CT scan and then the 12-bit and 16-bit CT images were reconstructed. The CT images were online transmitted to the Monaco planning system and a 0 ° of single field was designed. The dose distribution was calculated by PB (Pencil Beam), CC (Collapsed Cone) and MC (Monte Carlo) algorithms, respectively. The CT-ED curve was expanded and the dose was recalculated. The depth dose curve through the center of the metallic implants along with the direction of the field was obtained by using the Matlab 8.3 statistical software. The dose distribution curves between 12-bit and 16-bit CT images calculated by different algorithms and the dose difference of varying distances between the incident and the exit surfaces of metallic implants were statistically compared. The dose was measured by thimble chamber. Results The 16-bit CT images accurately read the CT values of the metallic implants. After the CT-ED curve was expanded, the dose on the incident surface of metallic implant was reduced by 5.43% and that on the exit surface was increased by 25.56% calculated by PB algorithm compared with MC algorithm. The dose on the posterior exit surface was higher than that of MC algorithm. The dose on the incident surface of metallic surface was decreased by 4.5%, whereas that on the exit surface was reduced by 4.31% using CC algorithm. The dose on the posterior exit surface was more significantly reduced. The calculated values by MC algorithm were the most close to the measured values. Conclusions Application of 16-bit CT image, CT-ED curve expansion of the treatment planning system combined with MC algorithm can enhance the accuracy of dose calculation for the patients containing metallic implants during radiotherapy.
Fund:Natural Science Foundation of Jiangsu Province (BK20151181)
Corresponding Authors:
Ni Xinye,Email:nxy2000@aliyun.com
Cite this article:
Lin Tao,Ni Xinye,Gao Liugang et al. Study of different dose calculation algorithms for the phantom of metallic implants[J]. Chinese Journal of Radiation Oncology, 2018, 27(7): 680-684.
Lin Tao,Ni Xinye,Gao Liugang et al. Study of different dose calculation algorithms for the phantom of metallic implants[J]. Chinese Journal of Radiation Oncology, 2018, 27(7): 680-684.
[1] 高留刚,金莲,倪昕晔.16-bit CT图像读取金属植入物CT值的应用[J].中国医学影像技术,2016,32(6):953-956.DOI:10.13929/j.1003-3289.2016.06.036. Gao LG,Jin L,Ni XY.Application of 16-bit CT image in reading CT values of metallic implants[J].Chin J Med Imag Technol,2016,32(6):953-956.DOI:10.13929/j.1003-3289.2016.06.036. [2] Chetty I,Curran BJ,Demarco J,et al. Report of the AAPM Task Group No.105:issues associated with clinical implementation of Monte Carlo-based photon and electron external beam treatment planning[J].Med Phys,2007,34(12):4818-4853.DOI:10.1007/BF01410611. [3] Verhaegen F,Seuntjens J.Monte Carlo modelling of external radiotherapy photon beams[J].Phys Med Biol,2003,48(48):R107-64.DOI:10.1088/0031-9155/48/21/R01. [4] Reynaert N,Marck SCVD,Schaart DR,et al. Monte Carlo treatment planning for photon and electron beams[J].Radiat Phys Chemist,2007,76(4):643-686.DOI:10.1016/j.radphyschem.2006.05.015. [5] Keall PJ,Chock LB,Jera JR,et al. Image reconstruction and the effect on dose calculation for hip prostheses[J].Medical Dosimetry,2003,28(2):113-117.DOI:10.1016/S0958-3947(02)00246-7. [6] Gao LG,Sun HF,Ni XY,et al. Metal artifact reduction through MV CBCT and kVCT in radiotherapy[J].Scient Rep,2016,6:37608.DOI:10.1038/srep37608. [7] Zhang Y,Yan H,Jia X,et al. A hybrid metal artifact reduction algorithm for x-ray CT[J].Med Phys,2013,40(4):041910.DOI:10.1118/1.4794474. [8] Hirata K,Utsunomiya D,Oda S,et al. Added value of a single-energy projection-based metal-artifact reduction algorithm for the computed tomography evaluation of oral cavity cancers[J].Japanese Journal of Radiology,2015,33(10):650.DOI:10.1007/s11604-015-0471-9. [9] Xin-Ye N,Liugang G,Mingming F,et al. Application of Metal Implant 16-Bit Imaging:New Technique in Radiotherapy[J].Technol Cancer Res Treat,2017,126(2):188-194.DOI:10.1177/1533034616649530. [10] 姜瑞瑶,熊霏,黄国锋.不同材质金属植入物对放疗剂量分布影响的研究[J].中国医疗器械杂志,2013,37(4):301-303.DOI:10.3969/j.issn.1671-7104.2013.04.019. Jiang RY,Xiong F,Huang GF.Research on the impact of metalimplants with different materials on radiation dose distribution[J].Chin J Med Instrument,2013,37(4):301-303.DOI:10.3969/j.issn.1671-7104.2013.04.019. [11] 刘明,李兴德,牛庆国,等.体内金属植入物对放疗剂量分布影响[J].中华放射肿瘤学杂志,2010,19(5):459-462.DOI:10.3760/cme.j.issn.1004-4221.2010.05.024. Liu M,Li XD,Niu QG,et al. Impact of implanted metal plates on radiation dose distribution in vivo[J].Chin J Radiat Oncol,2010,19(5):459-462.DOI:10.3760/cme.j.issn.1004-4221.2010.05.024. [12] 赵艳群,王培,黎杰,等.不同算法在非均匀组织模体中光子剂量计算精确度比较[J].中华放射肿瘤学杂志,2012,21(1)72-76.DOI:10.3760/cme.j.issn.1004-4221.2012.01.020. Zhao YQ,Wang P,Ni J,et al. Compare the calculation precision of collapsed cone convolution and pencil beam convolution algorithm in heterogeneous tissue[J].Chin J Radiat Oncol,2012,21(1)72-76.DOI:10.3760/cme.j.issn.1004-4221.2012.01.020. [13] Wieslander E, Knoos T.Dose perturbation in the presence of metallic implants:treatment planning system versus Monte Carlo simulations[J].Phys Med Biol,2003,48(20):3295-3305.DOI:10.1074/jbc. M707396200。 [14] 张建英,曾昭冲,孙菁.体内金属植入物对放疗剂量分布的影响及物理分析[J].中国医学物理学杂志,2005,22(3):505-507.DOI:10.3969/j.issn.1005-202X.2005.03.003 Zhang JY,Zeng ZC,Sun J.Dose perturbation of metal objects in patients and a study for the physical causation[J].Chin J Med Phys,2005,22(3):505-507.DOI:10.3969/j.issn.1005-202X.2005.03.003 [15] Glidehurst C,Chen D,Zhong H,et al. Changes realized from extended bit-depth and metal artifact reduction in CT[J].Med Phys,2013,39(6):061711-061711.DOI:10.1118/1.4805102. [16] Das IJ.Forward dose perturbation at high atomic number interfaces in kilovoltage x-ray beams[J].Med Phys,1997,24(24):1781-1787.DOI:10.1118/1.597943.
2018, Vol. 27 
