| Author: | Cheung, Ho Yin Anson |
| Title: | Investigation of respiratory gated (4D) positron emission tomography / computed tomography (PET/CT) imaging and treatment planning for tumor motion management in liver cancer radiotherapy |
| Advisors: | Cai, Jing (HTI) Wu, Vincent (HTI) |
| Degree: | DHSc |
| Year: | 2022 |
| Subject: | Liver -- Cancer -- Radiotherapy Radiotherapy Stereotaxic techniques Hong Kong Polytechnic University -- Dissertations |
| Department: | Faculty of Health and Social Sciences |
| Pages: | xii, 77 pages : color illustrations |
| Language: | English |
| Abstract: | Radiation therapy for not resectable primary and metastatic liver malignancies has shown feasible with advancement in oncology treatment planning and radiation delivery. Stereotactic body radiotherapy (SBRT) has been utilized to give highly accurate treatment plans aimed at allowing dose escalation to tumor while sparing liver tissue to reduce toxicity. The use of SBRT in the liver has shown a higher rate of local control than conventional fractionated radiotherapy. A major challenge in ensuring accurate and precise hepatic radiation therapy is to determine the trajectory of respiratory induced liver motion during treatment. Challenges with defining liver motion are not commonly seen in lung, liver radiotherapy includes target volumes directly overlapping adjacent critical structures, such as the liver itself. Furthermore, due to lack of radiographic contrast, it is difficult for physicians to clearly visualize and contour the tumor on 4D Computed Tomography (CT) alone. The respiratory induced liver motion may cause adverse effects on radiation therapy treatment planning and delivery, including the occurrence of inaccurate tumor and normal tissue localization, dosimetric uncertainty based on static CT images plan, the requirement of increasing planning target volume (PTV) margins, potentially leading to overdose the surrounding normal tissues and limit the maximum allowable dose that may securely be given to the tumor. To apply liver SBRT safely and effectively, it is particularly important to accurately monitor the trajectory of the tumor before radiotherapy treatment planning. The overarching goal of this thesis is to utilize the respiratory gated PET/CT technique for the liver cancer patients, integrate the gated PET/CT images for target volume delineation and finally evaluate two different radiotherapy techniques for liver cancer treatment planning and delivery. A prospective study was conducted to evaluate the potential clinical role and effectiveness of respiratory gated FDG F-18 PET/CT scan for liver cancer patients. The study population consisted of sixteen patients with a total number of eighty-nine lesions. Quantitative analysis of PET volume, Maximum Standard Uptake Value (SUVmax), Mean Standard Uptake Value (SUVmean) and Total Lesion Glycolysis (TLG) were compared between the gated PET/CT images and routine non-gated (3D) F-18 FDG PET/CT images. Gated PET/CT scan for liver malignancies in routine PET/CT examination was developed. Gated PET/CT scan for liver malignancies could improve the quality of PET image by improving the SUV accuracy of the lesions and reducing image blurring. In addition, a retrospective study was performed to investigate the effect of gated PET on target volume delineation for liver SBRT treatment planning. Six patients with eight liver lesions were recruited in the study. Compared to non-gated PET/CT aid contouring, gated PET/CT images provided clinical information on tumor trajectory and superior visual acuity. Gated PET allowed for more precise determination of planning target volume, and thus potentially helpful for normal liver tissue sparing and dose escalation in liver SBRT. Furthermore, a retrospective study was conducted to perform dosimetric comparison between Helical Tomotherapy (HT) (PrecisionTM, Radixact) and VMAT (Monaco® HD, VersaHD). Twelve liver cancer patients consecutively treated in the Hospital were enrolled. Planning CT and contours of these patients were retrieved and re-planned by HT. Dosimetric evaluations on coverages, hot spot, conformity index (CI), Homogeneity index (HI) and gradient index (GI) for plan target volume (PTV) were performed. Dosimetric statistics for specified organs at risk (OARs) were evaluated. The total monitor units per fraction (MU/fr) and delivery time were also analyzed. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 6674.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 2.23 MB | Adobe PDF | View/Open |
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