Abstract： Objective To investigate the impacts of ring applicator (Nucletron#090.617) reconstruction uncertainties on the radiation dose of computed tomography-guided three-dimensional (3D) brachytherapy for cervical cancer. Methods Twenty patients with cervical cancer who completed radical treatment were enrolled as subjects. In a treatment planning system, dose distribution was simulated with reconstruction uncertainties of tandem applicator, ring applicator, and both tandem and ring applicators, respectively. Two directions of reconstruction uncertainties were towards the tip (+) and the connector end (-) of the applicator. Reconstruction uncertainties of ±1 mm, ±2 mm, and ±3 mm were simulated. The D100, D90, and D50 for clinical target volume (CTV) and D0.1cc, D1cc, and D2cc for the bladder, rectum, and small intestine were evaluated. The effects of applicator reconstruction uncertainties on radiation dose of 3D brachytherapy were analyzed. Results The tandem applicator had greater impacts on radiation dose than the ring applicator. The dose deviation due to applicator reconstruction uncertainties increased with the increase in volume for CTV parameters but decreased with the increase in volume for parameters of organs at risk. The impacts of applicator reconstruction uncertainties were greatest on the dose to the small intestine. The deviation due to 3 mm reconstruction uncertainty of tandem applicator, ring applicator, and both tandem and ring applicators was 0.90%, 1.62%, and 1.74% for D90 of CTV, 1.33%, 1.53%, and 1.78% for D2cc of the bladder, 0.89%, 1.85%, and 1.97% for D2cc of the rectum, and 0.86%, 3.04%, and 3.50% for D2cc of the small intestine, respectively. Conclusions Applicator reconstruction uncertainties have certain impacts on the radiation dose of 3D brachytherapy. In order to improve the accuracy of brachytherapy, comprehensive quality control is recommended for applicator reconstruction.
Wang Xianliang,Yuan Ke,Kang Shengwei et al. Impacts of ring applicator reconstruction uncertainties on radiation dose in patients with cervical cancer[J]. Chinese Journal of Radiation Oncology, 2017, 26(3): 316-319.
[1] Ptter R,Haie-Meder C,Van Limbergen E,et al. Recommendations from gynaecological (GYN) GEC ESTRO working group (Ⅱ):concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy-3D dose volume parameters and aspects of 3D image-based anatomy,radiation physics,radiobiology[J].Radiother Oncol,2006,78(1):67-77.DOI:10.1016/j.radonc.2005.11.014. [2] EMBRACE. A European study on MRI-guided brachytherapy in locally advanced cervical cancer[EB/OL].2008.https://www.embracestudy.dk/UserUpload/PublicDocuments/EmbraceProtocol.pdf. [3] Hellebust TP,Kirisits C,Berger D,et al. Recommendationsfrom Gynaecological (GYN) GEC-ESTRO Working Group:considerations and pitfalls in commissioning and applicator reconstruction in 3D image-based treatment planning of cervix cancer brachytherapy[J].Radiother Oncol,2010,96(2):153-160.DOI:10.1016/j.radonc.2010.06.004. [4] Tanderup K,Hellebust TP,Lang S,et al. Consequences of random and systematic reconstruction uncertainties in 3D image based brachytherapy in cervical cancer[J].Radiother Oncol,2008,89(2):156-163.DOI:10.1016/j.radonc.2008.06.010. [5] Hellebust TP,Tanderup K,Bergstrand ES,et al. Reconstruction of a ring applicator using CT imaging:impact of the reconstruction method and applicator orientation[J].Phys Med Biol,2007,52(16):4893-4904.DOI:10.1088/0031-9155/52/16/012. [6] De Leeuw AAC,Moerland MA,Nomden C,et al. Applicator reconstruction and applicator shifts in 3D MR-based PDR brachytherapy of cervical cancer[J].Radiother Oncol,2009,93(2):341-346.DOI:10.1016/j.radonc.2009.05.003. [7] Perez-Calatayud J,Kuipers F,Ballester F,et al. Exclusive MRI-based tandem and colpostats reconstruction in gynaecological brachytherapy treatment planning[J].Radiother Oncol,2009,91(2):181-186.DOI:10.1016/j.radonc.2008.09.004. [8] Nath R,Anderson LL,Meli JA,et al. Code of practice for brachytherapy physics:report of the AAPM radiation therapy committee task group No.56[J].Med Phys,1997,24(10):1557-1598.DOI:10.1118/1.597966. [9] Schindel J,Zhang W,Bhatia SK,et al. Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer[J].J Contemp Brachyther,2013,5(4):250-257.DOI:10.5114/jcb.2013.39453.
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