摘要Objective This study aimed to investigate the dose calculation accuracy of individualized bulk electron density (IBED) assignment approaches for simulated magnetic resonance imaging (MRI)-only planning of thoracic tumors via the use of a 3DVH system. Methods 8 patients with thoracic cancer were included in this study. Based on standard planning CT,single-arc dynamic conformal therapy (DCT) and double-arc volumetric modulated arc therapy (VMAT) plans with a 6 MV photon beam were generated as a baseline plan (Plan-CT) for each patient. The simulated MRI-only planning (Plan-IBED) was implemented by copying the Plan-CT and forcing the electron density of each region of interest to its average value and recalculating the dose distribution. A 3DVH system was used to visualize and compare the dosimetric differences between Plan-CT and Plan-IBED,and the criteria of the 3D-Gamma pass rate were set to 1.0%/1.0 mm. Results The maximum percentage relative deviation (MPRD) of the dosimetric parameters D2,D95,D98,and Dmean of planning tumor volumes (PTVs) between Plan-CT and Plan-IBED was less than 1.3%. The MPRD of the average dose for organs at risk (OARs) was less than 1.5%. The MPRDs of the lung V5,V20,and V30 were 1.29%,3.26%,and 2.78%,respectively. Gamma analysis revealed an averaged pass rate of >95.0% for the body,as well as between 91.9% and 98.2% for OARs. Conclusion The proposed IBED assignment in simulated MRI-only treatment planning allows for dose calculation with comparable accuracy to the baseline plan and is appropriate for thoracic tumors.
Abstract：Objective This study aimed to investigate the dose calculation accuracy of individualized bulk electron density (IBED) assignment approaches for simulated magnetic resonance imaging (MRI)-only planning of thoracic tumors via the use of a 3DVH system. Methods 8 patients with thoracic cancer were included in this study. Based on standard planning CT,single-arc dynamic conformal therapy (DCT) and double-arc volumetric modulated arc therapy (VMAT) plans with a 6 MV photon beam were generated as a baseline plan (Plan-CT) for each patient. The simulated MRI-only planning (Plan-IBED) was implemented by copying the Plan-CT and forcing the electron density of each region of interest to its average value and recalculating the dose distribution. A 3DVH system was used to visualize and compare the dosimetric differences between Plan-CT and Plan-IBED,and the criteria of the 3D-Gamma pass rate were set to 1.0%/1.0 mm. Results The maximum percentage relative deviation (MPRD) of the dosimetric parameters D2,D95,D98,and Dmean of planning tumor volumes (PTVs) between Plan-CT and Plan-IBED was less than 1.3%. The MPRD of the average dose for organs at risk (OARs) was less than 1.5%. The MPRDs of the lung V5,V20,and V30 were 1.29%,3.26%,and 2.78%,respectively. Gamma analysis revealed an averaged pass rate of >95.0% for the body,as well as between 91.9% and 98.2% for OARs. Conclusion The proposed IBED assignment in simulated MRI-only treatment planning allows for dose calculation with comparable accuracy to the baseline plan and is appropriate for thoracic tumors.
基金资助:Grant sponsor:Guangzhou Special Fund for Scientific and Technological Innovation Development (Grant No.201804010297).
通讯作者:
Shuxu Zhang,Radiotherapy Center,Affiliated Cancer Hospital & Institute of Guangzhou Medical University,Guangzhou Guangdong 510095,China. E-mail: gthzsx@163.com
引用本文:
Shuxu Zhang, Qingxing Zeng, Yuliang Liao, Shengqu Lin, Guoquan Zhang, Huaiyu Lei, Ruihao Wang, Hui Yu, Quanbin Zhang, Ping Li. Dose Calculation Accuracy of Individualized Bulk Electron Density Assignment Approaches for Simulated MRI-only Planning of Thoracic Tumors[J]. 中国生物医学工程学报(英文版）, 2020, 29(3): 40-46.
Shuxu Zhang, Qingxing Zeng, Yuliang Liao, Shengqu Lin, Guoquan Zhang, Huaiyu Lei, Ruihao Wang, Hui Yu, Quanbin Zhang, Ping Li. Dose Calculation Accuracy of Individualized Bulk Electron Density Assignment Approaches for Simulated MRI-only Planning of Thoracic Tumors. Chinese Journal of Biomedical Engineering, 2020, 29(3): 40-46.
[1] Schmidt MA,Payne GS. Radiotherapy planning using MRI[EB/OL].Phys Med Biol,2015,60:R323-R361.https://doi.org/10.1088/0031-9155/60/22/R323 [2] Nyholm T,Nyberg M,Karlsson MG,et al. Systematisation of spatial uncertainties for comparison between a MR and a CT-based radiotherapy workflow for prostate treatments[EB/OL]. Radiat Oncol,2009,54. https://doi.org/10.1186/1748-717X-4-54. [3] Kristensen BH,Laursen FJ,L-gager V,et al. Dosimetric and geometric evaluation of an open low-field magnetic resonance simulator for radiotherapy treatment planning of brain tumours[EB/OL].Radiother Oncol,2008,87(1). https://doi.org 0-910.1016/j.radonc.2008.01.014. [4] Stanescu T,Jans HS,Pervez N,et al. A study on the magnetic resonance imaging (MRI)-based radiation treatment planning of intracranial lesions[J]. Phys Med Biol,2008,53(13):3579-3593. https://doi.org/10.1088/0031-9155/53/13/013. [5] Young T,Thwaites D,Holloway L. Assessment of electron density effects on dose calculation and optimisation accuracy for nasopharynx,for MRI only treatment planning[EB/OL]. Australas Phys Eng Sci Med,2018,41(4). https://doi.org/10.1007/s13246-018-0675-2. [6] Liu Y,Lei Y,Wang T,et al. MRI-based treatment planning for liver stereotactic body radiotherapy: validation of a deep learning-based synthetic CT generation method[EB/OL].Br J Radiol,2019,92(1100):20190067. https://doi.org/10.1259/bjr.20190067. [7] Han S,Yin FF,Cai J. Evaluation of dosimetric uncertainty caused by MR geometric distortion in MRI-based liver SBRT treatment planning[EB/OL]. J Appl Clin Med Phys,2019,20(2): 43-50. https://doi.org/10.1002/acm2.12520. [8] Prior P. MRI-based IMRT planning for MR-linac: comparison between CT- and MRI-based plans for pancreatic and prostate cancers[EB/OL]. Phys Med Biol,2016,61(10):3819-3842. https://doi.org/10.1088/0031-9155/61/10/3819. [9] Vanquin L,Boydev C,Korhonen J,et al. Radiotherapy treatment planning of prostate cancer using magnetic resonance imaging alone[EB/OL].Cancer Radiother,201923(4):281-289.https://doi.org/10.1088/0031-9155/61/10/3819. [10] Nejad-Davarani SP,Sevak P,Moncion M,et al. Geometric and dosimetric impact of anatomical changes for MR-only radiation therapy for the prostate[EB/OL].J Appl Clin Med Phys,2019,20(4):10-17.https://doi.org/10.1002/acm2.12551. [11] Kemppainen R,Vaara T,Joensuu T,et al. Accuracy and precision of patient positioning for pelvic MR-only radiation therapy using digitally reconstructed radiographs[EB/OL].Phys Med Biol,2018,63(5):055009. https://doi.org/10.1088/1361-6560/aaaD21. [12] Farjam R,Tyagi N,Deasy JO,et al. Dosimetric evaluation of an atlas-based synthetic CT generation approach for MR-only radiotherapy of pelvis anatomy[EB/OL].J Appl Clin Med Phys,2019,20(1):101-109.https://doi.org/10.1002/acm2.12501. [13] Bird D,Henry AM,Sebag-Montefiore D,et al. A systematic review of the clinical implementation of pelvic magnetic resonance imaging-only planning for external beam radiation therapy[EB/OL].Int J Radiat Oncol Biol Phys,2019,105(3):479-492.https://doi.org/10.1016/j.ijrobp.2019.06.2530. [14] Karotki A,Mah K,Meijer G,et al. Comparison of bulk electron density and voxel-based electron density treatment planning[EB/OL].J Appl Clin Med Phys,2011,12(4):3522. https://doi.org/10.1120/jacmp.V12i4.3522. [15] Hsu SH,Zawisza I,O'Grady K,et al. Towards abdominal MRI-based treatment planning using population-based Hounsfield units for bulk density assignment[EB/OL].Phys Med Biol,2018,63(15):155003.https://doi.org/10.1088/1361-6560/aacfb1. [16] Choi JH,Lee D,O'Connor L,et al. Bulk anatomical density based dose calculation for patient-specific quality assurance of MRI-Only prostate radiotherapy[EB/OL].Front Oncol,2019,9:997.https://doi.org/10.3389/fonc.2019.00997. [17] Largent A,Barateau Am,Nunes JC,et al. Pseudo-CT generation for MRI-Only radiation therapy treatment planning: comparison among patch-based,atlas-based,and bulk density methods[EB/OL]. Int J Radiat Oncol Biol Phys,2019,103(2):479-490.https://doi.org/10.1016/j.ijrobp.2018.10.002. [18] Prior P,Chen X,Gore E,et al. Technical Note: Is bulk electron density assignment appropriate for MRI-only based treatment planning for lung cancer[EB/OL].Med Phys,2017,44(7):3437-3443.https://doi.org/10.1002/mp.12267
