Actual measurement verification of dose calculation accuracy based on cone-beam CT images
Chen Li, Zhou Gang, Sun Yanze, Peng Qiliang, Han Jieguan, Tian Ye
Department of Radiotherapy Oncology, the Second Affiliated Hospital of Soochow University, Institute of Radiotherapy Oncology, Soochow University, Suzhou Key Laboratory for Radiation Oncology, Suzhou 215004, China
Abstract：Objective To evaluate the dose calculation accuracy of cone-beam CT (CBCT) image by actual measurement method. Methods CBCT images of 60 patients in the Second Affiliated Hospital of Soochow University from September, 2021 to May, 2022 were retrospectively analyzed. CBCT images of full-fan and half-fan scanning of the head, half-fan scanning of the chest and pelvis were obtained by the Varian OBI system. Hounsfield unit - electron density (HU-ED) curves corresponding to the scanning conditions were established with CIRS electron density phantom. The radiotherapy plans were designed on the CBCT images, and the dose calculation results of the detection point were compared with the ionization chamber measurement results to analyze the dose error. Then, three-dimensional dose verification system was adopted to detect the accuracy of the CBCT image radiotherapy plans implementation process in 60 patients, and the accuracy of dose calculation was verified according to the D99%, Dmean, D1% of target volume, Dmean and D1% of organs at risk (OAR), and the γ pass rate. Results In point dose detection in phantom, the dose calculation errors of CBCT images in the above four scanning patterns were -1.06%±0.87%、-1.67%±0.86%, 0.91%±0.73%, -1.54%±0.90%, respectively. In dosimetric verification based on patients' CBCT image treatment plan, the mean difference of Dmean, D99%, and D1% of planning target volume (PTV) in all scanning modes were not higher than 2%, and the Dmean and D1% differences of other OAR were not higher than 3%, except for the lens of patients in the head. The average γ values of target volume and OAR were less than 0.5 under the criteria of 3%/2 mm. Conclusions Under the condition of correctly establishing HU-ED curves, intensity-modulated radiation therapy (IMRT) / volumetric-modulated arc therapy (VMAT) planning based on CBCT images can be employed to estimate and monitor the actual dose to target volume and OAR in adaptive radiotherapy. Full-fan scanning patterns can further improve the accuracy of dose calculation for the head of patients.
Chen Li,Zhou Gang,Sun Yanze et al. Actual measurement verification of dose calculation accuracy based on cone-beam CT images[J]. Chinese Journal of Radiation Oncology, 2023, 32(6): 539-545.
[1] Schröder L, Stankovic U, Remeijer P, et al.Evaluating the impact of cone-beam computed tomography scatter mitigation strategies on radiotherapy dose calculation accuracy[J]. Phys Imaging Radiat Oncol, 2019,10:35-40. DOI: 10.1016/j.phro.2019.04.001. [2] Barateau A, De Crevoisier R, Largent A, et al.Comparison of CBCT-based dose calculation methods in head and neck cancer radiotherapy: from Hounsfield unit to density calibration curve to deep learning[J]. Med Phys, 2020,47(10):4683-4693. DOI: 10.1002/mp.14387. [3] Washio H, Ohira S, Funama Y, et al.Accuracy of dose calculation on iterative CBCT for head and neck radiotherapy[J]. Phys Med, 2021,86:106-112. DOI: 10.1016/j.ejmp.2021.05.027. [4] Iramina H, Nakamura M, Mizowaki T.Actual delivered dose calculation on intra-irradiation cone-beam computed tomography images: a phantom study[J]. Phys Med Biol, 2021,66(1):015007. DOI: 10.1088/1361-6560/abcdeb. [5] Wyatt JJ, Pearson RA, Walker CP, et al.Cone beam computed tomography for dose calculation quality assurance for magnetic resonance-only radiotherapy[J]. Phys Imaging Radiat Oncol, 2021,17:71-76. DOI: 10.1016/j.phro.2021.01.005. [6] Irmak S, Georg D, Lechner W.Comparison of CBCT conversion methods for dose calculation in the head and neck region[J]. Z Med Phys, 2020,30(4):289-299. DOI: 10.1016/j.zemedi.2020.05.007. [7] Yuan ZL, Rong Y, Benedict SH, et al."Dose of the day" based on cone beam computed tomography and deformable image registration for lung cancer radiotherapy[J]. J Appl Clin Med Phys, 2020,21(1):88-94. DOI: 10.1002/acm2.12793. [8] 李奇欣, 柏朋刚, 陈传本, 等. 基于头颈部千伏级锥形束CT的剂量计算研究[J].中华放射肿瘤学杂志,2011,20(4):334-337. DOI: 10.3760/cma.j.issn.1004-4221.2011.04.021. Li QX, Bai PG, Chen CB, et al.Dose calculation on kilovoltage cone-beam CT imaging for head and neck radiotherapy[J].Chin J Radiat Oncol,2011,20(4):334-337. DOI: 10.3760/cma.j.issn.1004-4221.2011.04.021. [9] Giacometti V, Hounsell AR, McGarry CK. A review of dose calculation approaches with cone beam CT in photon and proton therapy[J]. Phys Med, 2020,76:243-276. DOI: 10.1016/j.ejmp.2020.06.017. [10] Cao YY, Ma TJ, de Boer SF, et al. Image artifacts caused by incorrect bowtie filters in cone-beam CT image-guided radiotherapy[J]. J Appl Clin Med Phys, 2020,21(7):153-159. DOI: 10.1002/acm2.12888. [11] Boissonnat G, Chesneau H, Barat E, et al.Validation of histogram-based virtual source models for different IGRT kV-imaging systems[J]. Med Phys, 2020,47(9):4531-4542. DOI: 10.1002/mp.14311. [12] Lindsay C, Bazalova-Carter M, Wang A, et al.Investigation of combined kV/MV CBCT imaging with a high-DQE MV detector[J]. Med Phys, 2019,46(2):563-575. DOI: 10.1002/mp.13291. [13] Jeong Y, Oh JG, Kang JK, et al.Three-dimensional dose reconstruction-based pretreatment dosimetric verification in volumetric modulated arc therapy for prostate cancer[J]. Radiat Oncol J, 2020,38(1):60-67. DOI: 10.3857/roj.2020.00066. [14] Chen A, Zhu JH, Wang N, et al.Comparison of three-dimensional patient-specific dosimetry systems with delivery errors: Toward a new synchronous measurement method[J]. Phys Med, 2021,90:134-141. DOI: 10.1016/j.ejmp.2021.09.013. [15] Puzhakkal N, Kochunny AK, Makuny D, et al.Validation of dolphin dosimetry in three dimensional patient-specific quality assurance programme[J]. Rep Pract Oncol Radiother, 2019,24(5):481-490. DOI: 10.1016/j.rpor.2019.07.006. [16] Rigaud B, Simon A, Castelli J, et al.Evaluation of deformable image registration methods for dose monitoring in head and neck radiotherapy[J]. Biomed Res Int, 2015,2015:726268. DOI: 10.1155/2015/726268. [17] Heukelom J, Kantor ME, Mohamed A, et al.Differences between planned and delivered dose for head and neck cancer, and their consequences for normal tissue complication probability and treatment adaptation[J]. Radiother Oncol, 2020,142:100-106. DOI: 10.1016/j.radonc.2019.07.034. [18] van Kranen S, Hamming-Vrieze O, Wolf A, et al. Head and neck margin reduction with adaptive radiation therapy: robustness of treatment plans against anatomy changes[J]. Int J Radiat Oncol Biol Phys, 2016,96(3):653-660. DOI: 10.1016/j.ijrobp.2016.07.011. [19] Zhang Y, Yue N, Su MY, et al.Improving CBCT quality to CT level using deep learning with generative adversarial network[J]. Med Phys, 2021,48(6):2816-2826. DOI: 10.1002/mp.14624. [20] Belshaw L, Agnew CE, Irvine DM, et al.Adaptive radiotherapy for head and neck cancer reduces the requirement for rescans during treatment due to spinal cord dose[J]. Radiat Oncol, 2019,14(1):189. DOI: 10.1186/s13014-019-1400-3. [21] de Smet M, Schuring D, Nijsten S, et al. Accuracy of dose calculations on kV cone beam CT images of lung cancer patients[J]. Med Phys, 2016,43(11):5934. DOI: 10.1118/1.4964455. [22] Hatton J, McCurdy B, Greer PB. Cone beam computerized tomography: the effect of calibration of the Hounsfield unit number to electron density on dose calculation accuracy for adaptive radiation therapy[J]. Phys Med Biol, 2009,54(15):N329-346. DOI: 10.1088/0031-9155/54/15/N01.
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