Dose attenuation in intensity-modulated radiotherapy and volumetric modulated arc therapy caused by different treatment couches
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Author(s)
Abstract
Purpose: This study aimed to analyze the dose attenuation caused by four kinds of commonly used commercial treatment couches (Elekta iBEAM evo Couch, Varian Exact Couch (Standard Couch), Varian Exact IGRT Couch, and BrainLAB imaging Couch) in IMRT and VMAT. Method: Six patients with prostate cancer were planned with both 6 MV 5-field , 7-field , 9-field IMRT plan and 2-arc (152º-212º and 210º-150º) VMAT plan in the treatment planning system (TPS). Compared the dose distribution difference with and without treatment couches in the TPS. The mean dose, dose covering 95% of the target volume, and the isocenter dose of the planning target volume were evaluated. Results: The dose attenuation was 1.46%-3.13% with Elekta iBEAM evo Couch, 0.72%-1.63% with Varian Exact Couch (Standard Couch), 0.86%-2.02% with Varian Exact IGRT Couch, and 1.51%-3.15% with BrainLAB imaging Couch. In the clinical evaluation, the dose attenuation was 1.24%- 3.15% in 5F- IMRT, 0.73%- 1.73% in 7F- IMRT, 1.39%-2.83% in 9F- IMRT, and 0.72%-1.78% in VMAT. Besides, the relative position between the patient and treatment couch was changed daily according to the record in the Elekta Mosaiq system. The shift of the treatment couches relative to the patient's position ranged from -2.00 cm to +2.00 cm. Simulation of treatment couch shift in the TPS showed that a treatment couch shift by 2 cm to the right or the left caused a maximum dose change of 0.65% and an average dose change of less than 0.30%. Conclusion: The dose attenuation caused by the treatment couch is obvious in IMRT and VMAT, suggesting the necessity of incorporating the accurate couch model in the TPS to minimize dose difference between the computed dose in TPS and the delivered dose to patient in actual treatment. The average dose attenuation is less in 7F-IMRT and VMAT than in 5F-IMRT and 9F-IMRT among four treatment couches. Varian Exact Couch (Standard Couch) and Varian Exact IGRT Couch cause less average dose attenuation than Elekta iBEAM evo Couch and BrainLAB imaging Couch. The position of patients relative to the treatment couch, which may vary in daily set-up, does not cause significant impact on the target dose in the treatment.
Keywords
Prostatic Cancer, Treatment Couch, Dosimetry, Intensity-modulated Radiotherapy(IMRT), Volumetric Modulated Arc Therapy(VMAT)
Cite this paper
Ni Qianxi, Wong Peifong, Zhang Jiutang, Chen Ni,
Dose attenuation in intensity-modulated radiotherapy and volumetric modulated arc therapy caused by different treatment couches
, SCIREA Journal of Clinical Medicine.
Volume 4, Issue 4, August 2019 | PP. 109-119.
References
[ 1 ] | Loch AJ, Gerig L, Li H, et al. Dosimetric effects caused by couch tops and immobilization devices: report of AAPM task group 176 . Med Phys 2014; 41 (6): 1-30. |
[ 2 ] | Zhang RH, Gao YL, Bai WW. Quantification and comparison the dosimetric impact of two treatment couch model in VMAT. J Appl Clin Med Phys 2017. |
[ 3 ] | Duggar WN, Nguyen A, Stanford J, et al. Modeling treatment couches in the Pinnacle treatment planning system: Especially important for arc therapy. Med Dosim 2016; 41(1): 34-41. |
[ 4 ] | Yu Chun-Yen, Chou Wen-Tsae, Liao Yi-Jen, et al. Impact of radiation attenuation by a carbon fiber couch on patient dose verification. Sci Rep 2017; 7: 43336. |
[ 5 ] | Chavaudra J, ridier A. Definition of volumes in external radiotherapy: ICRU reports 50 and 62. Cancer Radiother 2001; 5(5): 472-478. |
[ 6 ] | Li H, Lee AK, Johnso JL, et al. Characterization of dose impact on IMRT and VMAT from couch attenuation for two Varian couches . J Appl Clin Med Phys 2011; 12(3): 23-31. |
[ 7 ] | Pilllam KB, Howell RM, Followill D, et al. The clinical impact of the couch top and rails on IMRT and arc therapy . Phys Med Biol 2011; 56(23): 7435-7447. |
[ 8 ] | Gay H, Niemierkoa. A free program for calculating EUD-based NTCP and TCP in external beam radiotherapy. Phys Med 2007; 23(3-4): 115-125. |
[ 9 ] | Mihaylov I B, Corry P, Yan Y, et al. Modeling of carbon fiber couch attenuation properties with a commercial treatment planning system. Med Phys 2008; 35(11): 4982-4988. |
[ 10 ] | Wang LY, Bai PG, Li QX,et al. The study of the attenuation and isotropic of Elekta carbon fiber couch. Medical Equipment 2010; 23 (7): 1-3. |
[ 11 ] | Liu J,Song P. The effect of treatment couch on the gantry angle. Jilin Medical Journal 2012; 33 (24): 5273-5274. |
[ 12 ] | Gan JY, Hu YX, Hong W, et al. The effect of the six-dimensional whole carbon fiber bed board of Elekta linear accelerator on the radiation dose of posterior oblique field. China Cancer 2010; 19(8): 511-513. |
[ 13 ] | Aldosary G, Nobah A, Alzorkani F, et al. A practical method of modeling a treatment couch using cone-beam computed tomography for intensity-modulated radiation therapy and RapidArc treatment delivery. Med Dosim 2015; 92(2): 139-146. |
[ 14 ] | Xiong L, Halvorsen. Modeling Linac Couch Effects On Attenuation and Skin Dose. Med Phys 2014; 41(6): 277. |
[ 15 ] | Park Jong Min, Park So-Yeon, Wu Hong-Gyun, et al. Improvement of VMAT plan quality for head and neck cancer with high resolution fluences generated by couch shift between arcs. Phys Med 2018; 46: 1-6. |
[ 16 ] | Sedaghatian T, Momennezhad M, Rasta S H, et al. An Update of Couch Effect on the Attenuation of Megavoltage Radiotherapy Beam and the Variation of Absorbed Dose in the Build-up Region. J Biomed Phys Eng 2017; 7(3): 279-288. |
[ 17 ] | Chyou Te-Yu, Lorenz Friedlieb. Couch modelling for volumetric modulated arc therapy (VMAT). Australas Phys Eng Sci Med 2017. |
[ 18 ] | Gelover E, Dalhart A, Hyer .The Impact of Modeling the Treatment Couch On Patient Specific VMAT QA. Med Phys 2016; 43(6): 3531. |
[ 19 ] | Zhang R, Bai W, Xiaomei F, et al..Characterization of Dose Impact On Different Beam Fields Size Attenuation for Elekta IGRT Couch. Med Phys 2015; 42(6): 3235. |
[ 20 ] | Zhang R, Bai W, Fleckenstein. Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT. Med Phys 2015; 42(6): 3486. |