Dose accumulation of volumetric modulated arc radiation therapy for prostate cancer using deformable image registration

Name: Achawee Suwannarat

ThaSH: Cone-Beam Computed Tomography -- methods

ThaSH: Image registration

ThaSH: Diagnostic Imaging

Abstract: Cone-beam computed tomography (CBCT) is typically aimed for pre-treatment setup verification to ensure treatment accuracy. However, their three-dimensional anatomical information of the patient on the treatment day has also showed the potential for adaptive radiation therapy and as to be the dose monitoring system. The aim of this work is to study the proper procedure of using CBCT images and Velocity AI 3.2.0 deformable image registration (DIR) software in predicting the accumulated dose for conventional fraction VMAT prostate cancer patients and to investigate and verify the accuracy of DIR software. The CBCT image quality was firstly evaluated using Catphan 600 phantom underwent on-board imaging (OBI). Then, the accuracy of DIR using Velocity AI 3.2.0 software was evaluated. The CBCT HU to electron density calibration curve was generated using CIRS CBCT electron density phantom-062A. Then, the accuracy of planning CT (PCT)-based dose calculation (DPCT), CBCT-based dose calculation (DCBCT) and dose deformation from PCT to CBCT image using DIR property was verified by comparing with dose measurements using IC (0.13cc) and Gafchromic EBT3 film on CIRS pelvic phantom model 002PRA. In clinical investigation, planning target volume (PTV) and organ at risks (OARs) were deformed from PCT to fractionated CBCT by Velocity AI 3.2.0 DIR software and modified by radiation oncologist. Dose distribution in each CBCT fraction was generated using CBCT HU to electron density calibration curve and calculated on EclipseTM treatment planning system 13.6.0. Dose in every fractionated CBCT was deformed, summed and mapped on PCT. The variation of the organ volume as well as the dosimetric parameters following the QUANTEC-guideline for PTV and OARs were collected and analyzed. The results showed the CBCT image quality and the accuracy of DIR using DIR protocol which was implemented in Velocity AI software were in the acceptable level of AAPM TG No. 179 and 132, respectively. Point dose differences in phantom between the measurements and DPCT, DCBCT, and dose deform were 2.03%, 2.28% and 2.73%, respectively. DPCT, DCBCT and dose deform compared with the measurement dose for dose distribution were 91.23%, 87.7% and 85.40% when considering at the (3%/3mm) gamma passing rate. In clinical investigation, the volume ratios of CBCT/PCT for PTV, bladder and rectum were found to be 1.02, 0.92 and 0.94. The dose differences of predicted accumulation dose using CBCT dose calculation and planning dose were -4.24 Gy for D95% of PTV, -1.32 Gy and -4.80 cc for Dmean and V70Gy of bladder, and -1.37 Gy, and -1.74 cc for Dmean and V70Gy of rectum, respectively. In conclusion, the accumulation dose using CBCT image and DIR to guide organ contouring is found to be feasible and adequate to predict the actual dose delivery to the VMAT prostate cancer

Mahidol University. Mahidol University Library and Knowledge Center

Address: NAKHONPATHOM

Email: liwww@mahidol.ac.th

Name: Lalida Tuntipumiamorn

Role: Thesis Advisors

Name: Pittaya Dankulchai

Role: Thesis Advisors

Name: Nuanpen Damrongkijudom

Role: Thesis Advisors

Created: 2019

Modified: 2024-02-16

Issued: 2024-02-16

วิทยานิพนธ์/Thesis

application/pdf

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Radiological Technology

Grantor: Mahidol University

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