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Oyoshi H, Tachibana H, Someya T, Rachi T, Takeda Y, Ariji T. [A Preliminary Study of Optimal Imaging Acquisition Parameters for Fiducial Markers in Liver Stereotactic Body Radiotherapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2021; 77:1400-1410. [PMID: 34924476 DOI: 10.6009/jjrt.2021_jsrt_77.12.1400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In liver stereotactic body radiotherapy (SBRT) using fiducial markers, the accuracy of automatic image recognition of fiducial markers is important, and the imaging dose cannot be neglected in image-guided radiotherapy. Optimal imaging parameters of fiducial markers were investigated for automatic image recognition and imaging dose. We investigated automatic recognition with fiducial markers of different shapes and sizes. In addition, the optimum imaging conditions were examined based on the automatic recognition when the presence or absence of a filter, focal spot size, and phantom thickness were altered using the fiducial markers with a high automatic recognition. The results for different shapes and sizes of fiducial markers showed that larger markers were recognized more automatically, whereas shorter markers were recognized in the correct position. By using the filter, we were able to reduce the imaging dose by one third or one half compared to the case without the filter. The results for the focal spot size showed that using a larger size resulted in higher automatic recognition accuracy than using a smaller size. For the relationship between the automatically recognized imaging conditions and the air kerma when the phantom thickness was altered, it was necessary to keep the tube current-time product constant and increase the tube voltage in order to avoid poor recognition accuracy. The parameters we proposed are effective in shortening the treatment time and reducing the imaging dose because they allow us to acquire images with low doses and high accuracy of automatic recognition.
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Affiliation(s)
- Hajime Oyoshi
- Department of Radiology, National Cancer Center Hospital East
| | - Hidenobu Tachibana
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital East
| | - Takashi Someya
- Department of Radiology, National Cancer Center Hospital East
| | - Toshiya Rachi
- Department of Radiology, National Cancer Center Hospital East
| | - Youhei Takeda
- Department of Radiology, National Cancer Center Hospital East (Current address: Department of Radiology, Shinshu Ueda Medical Center)
| | - Takaki Ariji
- Department of Radiology, National Cancer Center Hospital East
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Wang T, Inubushi S, Ikeo N, Mukai T, Okumura K, Akasaka H, Yada R, Yoshida K, Miyawaki D, Ishihara T, Nakaoka A, Sasaki R. Novel artifact-robust and highly visible zinc solid fiducial marker for kilovoltage x-ray image-guided radiation therapy. Med Phys 2020; 47:4703-4710. [PMID: 32696571 DOI: 10.1002/mp.14412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To develop a novel biocompatible solid fiducial marker that prevents radiopaque imaging artifacts and also maintains high imaging contrast for kilovoltage x-ray image-guided radiation therapy. METHODS The fiducial marker was made of pure zinc. An in-house water-equivalent phantom was designed to evaluate artifacts and visibility under various simulated treatment scenarios. Image artifacts were quantitatively assessed in terms of the metal artifact index (MAI) on kilovoltage computed tomography (CT) and cone-beam CT (CBCT) scans. Marker visibility was evaluated on two types of kilovoltage planar x-ray images in terms of the contrast-to-background ratio (CBR). Comparisons with a conventional gold fiducial marker were conducted. RESULTS The use of zinc rather than a gold marker mitigates imaging artifacts. The MAI near the zinc marker decreased by 76, 79, and 77 % in CT, and by 77 (81), 74 (80), and 79 (85) % in CBCT full-fan (half-fan) scans, when using one-, two-, and three-marker phantom settings, respectively. The high-contrast part of the zinc marker exhibited CBRs above 2.00 for 28/32 exposures under four (lung, tissue, low-density bone, and high-density bone) different simulation scenarios, making its visibility comparable to that of the gold marker (30/32 exposures with CBRs > 2.00). CONCLUSIONS We developed a biocompatible, artifact-robust, and highly visible solid zinc fiducial marker. Although further evaluation is needed in clinical settings, our findings suggest its feasibility and benefits for kilovoltage x-ray image-guided radiation therapy.
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Affiliation(s)
- Tianyuan Wang
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Sachiko Inubushi
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Naoko Ikeo
- Department of Mechanical Engineering, Kobe University Graduate School of Engineering Faculty of Engineering, 1-1 Rokkodai-cho, Kobe, Hyogo, 657-8501, Japan
| | - Toshiji Mukai
- Department of Mechanical Engineering, Kobe University Graduate School of Engineering Faculty of Engineering, 1-1 Rokkodai-cho, Kobe, Hyogo, 657-8501, Japan
| | - Keisuke Okumura
- Centre for Radiology and Radiation Oncology, Kobe University Hospital, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Hiroaki Akasaka
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Ryuichi Yada
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Kenji Yoshida
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Daisuke Miyawaki
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Takeaki Ishihara
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Ai Nakaoka
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Ryohei Sasaki
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
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