2017 Fiscal Year Annual Research Report
ピクセル型放射線検出器を用いた動的適応小線源治療システムの開発
| Project/Area Number |
16J04075
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| Research Institution | Kyushu University |
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Principal Investigator |
Tran Thi Thao Nguyen 九州大学, 医学系学府, 特別研究員(DC1)
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| Project Period (FY) |
2016-04-22 – 2019-03-31
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| Keywords | Cervical cancer / Brachytherapy / Heterogeneous materials / Monte Carlo simulation / 3D gamma analysis / Applicator |
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| Outline of Annual Research Achievements |
In this year, more clinical cases of planning computerized tomography (CT) images of cervical cancer patient who received intracavitary brachytherapy at Kagoshima University Hospital were collected for developing the proposed framework. In addition, the analysis of dose distributions in clinical treatment planning was performed for new clinical cases. The effects of brachytherapy applicator and tissue heterogeneity on dose distributions have been evaluated in intracavitary brachytherapy for cervical cancer. The dosimetric errors that occur due to the presence of a brachytherapy applicator and human tissues in dose calculation in the treatment planning system of cervical intracavitary brachytherapy, has been evaluated by using Monte Carlo simulation and gamma analysis. Gamma pass rates representing degree of dose agreement between two dose distributions decreased with the volume of interests (VOI) increasing, reached the minimum, and gradually increased for all treatment fractions. Consequently, the changes in the gamma pass rates were observed on the VOIs.
This research has been published in 1 international interdisciplinary meeting (the 10th Hope Meeting with Nobel Laureates) and 2 domestic conferences (the 113th and 115th Scientific Meeting of the Japan Society of Medical Physics), in which the research could receive helpful and constructive comments. In addition, the research has selected to present in the 10th Hope Meeting with Nobel Laureates with oral and poster presentations.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Our purpose is to develop a dynamic adaptive brachytherapy system for real-time visualization of four-dimensional in vivo locations of an applicator, 192Ir source, tumor, OAR, and dose distributions for intracavitary brachytherapy using a pixel-based portable radiation camera. For that purpose, the effects of applicator and inhomogeneous tissues on dose distributions for cervical cancer intracavitary brachytherapy have been investigated using Monte Carlo simulation. To evaluate the impacts of heterogeneous materials on dose distributions, the comparisons of water phantoms and patient physical maps, which were constructed by converting CT values of CT images, were performed on Monte Carlo-based dose distributions by using gamma analysis. Second, we has designed the a pixel-based portable radiation camera using Monte Carlo simulations based on the Particle and Heavy Ion Transport (PHITS) code System, and an automated system for dynamic estimation of seed locations for cervical intracavitary brachytherapy. As a proof-of-concept study, a patient physical map based on planning CT image was employed in this study. 192Ir seed and gamma camera were positioned in the patient physical map.
The results have been published in 1 international interdisciplinary meeting and 2 domestic conferences in which the research could receive helpful and constructive comments. In addition, the research has selected to present in the 10th Hope Meeting with Nobel Laureates with oral and poster presentations.
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| Strategy for Future Research Activity |
We will improve the automated system for dynamic estimation of seed locations based on a pixel-based portable radiation camera using Monte Carlo simulations based on the Particle and Heavy Ion Transport code System. First, the effects of heterogeneous materials including patient body and applicators on dose distributions for cervical cancer intracavitary brachytherapy have been investigated for improving the automated estimation of seed locations using Monte Carlo simulation. Next an automated recognition approach for the applicator, source, tumor, and OAR will be developed for the treatment of cervical cancer in intracavitary brachytherapy. In addition, an estimation approach for planning computerized tomography images during the treatment time using a 2D/3D image registration will be developed. Then, 4D dose distribution during the treatment time will be estimated. Finally, pixel-based portable radiation camera with the pinhole collimator and the pixel-based gamma ray semiconductor detector will be designed and integrated with remote after-loading system. The results will be presented in the international and domestic conferences and submitted to international journal.
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| Remarks |
Selected student, at the 10th Hope Meeting with Nobel Laureates, Japan, 2018.03. 23 ~ 15.
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