Leaf open time sinogram (LOTS): a novel approach for patient specific quality assurance of total marrow irradiation

Radiation Oncology

N. Arunai Nambi Raj¹  Jose Easow²  Rangasamy Sivaraman³  Suryakant Kaushik³  Dayananda Shamurailatpam Sharma³  K. Ganapathy³  Kartikeswar Ch. Patro³  Arjunan Manikandan³  Mayur Sawant³  M. P. Noufal³  Rajesh Thiyagarajan⁴  Sham C. Sundar⁵  Srinivas Chilukuri⁵  Rakesh Jalali⁵ 

[1] Centre for Biomaterials, Cellular and Molecular Theranostics (CBCMT), VIT University, 632014, Vellore, India;Department of Haematology, Blood and Marrow Transplantation, Apollo Speciality Hospital, Teynampet, Chennai, India;Department of Medical Physics, Apollo Proton Cancer Centre, 100 Feet Road Tharamani, 600096, Chennai, Tamil Nadu, India;Department of Medical Physics, Apollo Proton Cancer Centre, 100 Feet Road Tharamani, 600096, Chennai, Tamil Nadu, India;School of Advanced Sciences, VIT University, 632014, Vellore, India;Department of Radiation Oncology, Apollo Proton Cancer Centre, 100 Feet Road Tharamani, 600096, Chennai, Tamil Nadu, India;

关键词: Sinogram;    Exit dosimetry;    Dose Reconstruction;    Patient specific QA;    Total marrow irradiation;    Helical tomotherapy;    MVCT;   

DOI  :  10.1186/s13014-020-01669-2

来源: Springer

【 摘 要 】

There is no ideal detector-phantom combination to perform patient specific quality assurance (PSQA) for Total Marrow (TMI) and Lymphoid (TMLI) Irradiation plan. In this study, 3D dose reconstruction using mega voltage computed tomography detectors measured Leaf Open Time Sinogram (LOTS) was investigated for PSQA of TMI/TMLI patients in helical tomotherapy. The feasibility of this method was first validated for ten non-TMI/TMLI patients, by comparing reconstructed dose with (a) ion-chamber (IC) and helical detector array (ArcCheck) measurement and (b) planned dose distribution using 3Dγ analysis for 3%@3mm and dose to 98% (D98%) and 2% (D2%) of PTVs. Same comparison was extended for ten treatment plans from five TMI/TMLI patients. In all non-TMI/TMLI patients, reconstructed absolute dose was within ± 1.80% of planned and IC measurement. The planned dose distribution agreed with reconstructed and ArcCheck measured dose with mean (SD) 3Dγ of 98.70% (1.57%) and 2Dγ of 99.48% (0.81%). The deviation in D98% and D2% were within 1.71% and 4.10% respectively. In all 25 measurement locations from TMI/TMLI patients, planned and IC measured absolute dose agreed within ± 1.20%. Although sectorial fluence verification using ArcCHECK measurement for PTVs chest from the five upper body TMI/TMLI plans showed mean ± SD 2Dγ of 97.82% ± 1.27%, the reconstruction method resulted poor mean (SD) 3Dγ of 92.00% (± 5.83%), 64.80% (± 28.28%), 69.20% (± 30.46%), 60.80% (± 19.37%) and 73.2% (± 20.36%) for PTVs brain, chest, torso, limb and upper body respectively. The corresponding deviation in median D98% and D2% of all PTVs were < 3.80% and 9.50%. Re-optimization of all upper body TMI/TMLI plans with new pitch and modulation factor of 0.3 and 3 leads significant improvement with 3Dγ of 100% for all PTVs and median D98% and D2% < 1.6%. LOTS based PSQA for TMI/TMLI is accurate, robust and efficient. A field width, pitch and modulation factor of 5 cm, 0.3 and 3 for upper body TMI/TMLI plan is suggested for better dosimetric outcome and PSQA results.

【 授权许可】

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