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Tsuzuki Y, Kamei M, Iwata H, Takeda R, Kimura H, Aiba H, Murase T, Tsuchiya T, Sasaki R, Hiwatashi A. Impact of cyclophosphamide on the morphological and histological changes in polyglycolic acid spacers. JOURNAL OF RADIATION RESEARCH 2024; 65:725-732. [PMID: 39250811 PMCID: PMC11420979 DOI: 10.1093/jrr/rrae070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 07/10/2024] [Indexed: 09/11/2024]
Abstract
In radiotherapy for pediatric abdominal tumors, determining the effect of concurrent chemotherapy on polyglycolic acid (PGA) spacers is crucial; yet this effect has not been validated. Therefore, we aimed to evaluate the impact of cyclophosphamide (CPA) chemotherapy on the PGA spacer using a rat model. Twenty-four rats were implanted with the spacer, and morphological changes in the spacer were assessed on CT for both the CPA-dosed group (40 mg/kg) and the control group. The size and volume of the spacer were quantified using CT, while the degree of adhesion and microscopic examination of the tissue were determined using pathology specimens. Morphologically, the size of the spacer decreased over time in both the CPA-dosed and control groups, with no significant differences observed between groups. No significant differences in adhesion were observed between the two groups. Macrophages were observed around the PGA fibers, suggesting their involvement in the degradation of the PGA spacer. These results suggest that CPA does not cause significant clinically problematic degradation or adverse tissue reactions to the PGA spacer. This study reinforced the benefits of PGA spacers; however, future research focusing on in vivo longitudinal monitoring of individual rats, as well as on humans, is required.
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Affiliation(s)
- Yusuke Tsuzuki
- Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City University West Medical Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Michi Kamei
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Hiromitsu Iwata
- Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City University West Medical Center, 1-1-1 Hirate-cho, Kita-ku, Nagoya 462-8508, Japan
| | - Risa Takeda
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Hiroaki Kimura
- Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Hisaki Aiba
- Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Takayuki Murase
- Department of Pathology and Molecular Diagnostics, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
| | - Takahiro Tsuchiya
- Central Department of Radiology, Nagoya City University Hospital, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8602, Japan
| | - Ryohei Sasaki
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Akio Hiwatashi
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
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Wu YH, Shen SH, Wang YP, Chang NW, Lee PC, Li CP, Lan KL, Shiau CY, Hu YW, Huang PI, Hsu CX, Yen SH, Hsu SM. Feasibility estimation of injected hydrodissection before definitive radiotherapy of pancreatic adenocarcinoma. J Chin Med Assoc 2024; 87:511-515. [PMID: 38478012 DOI: 10.1097/jcma.0000000000001084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Pancreatic adenocarcinoma is often not diagnosed until an advanced stage, and so most patients are not eligible for resection. For patients who are inoperable, definitive radiotherapy is crucial for local disease control. However, the pancreas is located close to other vulnerable gastrointestinal organs, making it challenging to deliver an adequate radiation dose. The surgical insertion of spacers or injection of fluids such as hydrogel before radiotherapy has been proposed, however, no study has discussed which patients are suitable for the procedure. METHODS In this study, we reviewed 50 consecutive patients who received definitive radiotherapy at our institute to determine how many could have benefitted from hydrodissection to separate the pancreatic tumor from the adjacent gastrointestinal tract. By hypothetically injecting a substance using either computed tomography (CT)-guided or endoscopic methods, we aimed to increase the distance between the pancreatic tumor and surrounding hollow organs, as this would reduce the radiation dose delivered to the organs at risk. RESULTS An interventional radiologist considered that hydrodissection was feasible in 23 (46%) patients with a CT-guided injection, while a gastroenterologist considered that hydrodissection was feasible in 31 (62%) patients with an endoscopic injection. Overall, we found 14 (28%) discrepancies among the 50 patients reviewed. Except for 1 patient who had no available trajectory with a CT-guided approach but in whom hydrodissection was considered feasible with an endoscopic injection, the other 13 patients had different interpretations of whether direct invasion was present in the CT images. CONCLUSION Our results suggested that about half of the patients could have benefited from hydrodissection before radiotherapy. This finding could allow for a higher radiation dose and potentially better disease control.
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Affiliation(s)
- Yuan-Hung Wu
- Department of Heavy Particles and Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Therapeutic and Research Center of Pancreatic Cancer, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Shu-Huei Shen
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Yen-Po Wang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Therapeutic and Research Center of Pancreatic Cancer, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Nai-Wen Chang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Pei-Chang Lee
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Therapeutic and Research Center of Pancreatic Cancer, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Chung-Pin Li
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Therapeutic and Research Center of Pancreatic Cancer, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Division of Clinical Skills Training, Department of Medical Education, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Keng-Li Lan
- Department of Heavy Particles and Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Therapeutic and Research Center of Pancreatic Cancer, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Institute of Traditional Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
| | - Cheng-Yin Shiau
- Department of Heavy Particles and Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
| | - Yu-Wen Hu
- Department of Heavy Particles and Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
| | - Pin-I Huang
- Department of Heavy Particles and Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Therapeutic and Research Center of Pancreatic Cancer, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Chen-Xiong Hsu
- Department of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan, ROC
| | - Sang-Hue Yen
- Department of Heavy Particles and Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
- Department of Radiation Oncology, Taipei Municipal Wan-Fang Hospital, Taipei, Taiwan, ROC
| | - Shih-Ming Hsu
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC
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Komatsu S, Wang T, Terashima K, Demizu Y, Anzai M, Suga M, Yamashita T, Suzuki O, Okimoto T, Sasaki R, Fukumoto T. Innovative Combination Treatment to Expand the Indications of Particle Therapy: Spacer Placement Surgery Using Bio-Absorbable Polyglycolic Acid Spacer. J Am Coll Surg 2024; 238:119-128. [PMID: 37737669 DOI: 10.1097/xcs.0000000000000873] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
BACKGROUND Particle therapy has favorable dose distribution and high curability. However, radiotherapy for malignant tumors adjacent to the gastrointestinal tract is contraindicated owing to its low tolerance. To overcome this, combination treatment with surgery to make a space between the tumor and adjacent gastrointestinal tract followed by particle therapy has been developed. Several materials have been used for the spacer and recently, we developed the absorbable polyglycolic acid (PGA) spacer, which has been used since 2019. This study is the first report of consecutive case series of spacer placement surgery using the PGA spacer. STUDY DESIGN Fifty consecutive patients undergoing spacer placement surgery with the PGA spacer were evaluated. Postoperative laboratory data, morbidity related to the treatment, and spacer volume after treatment were evaluated. RESULTS There were no treatment-related deaths, and all but 2 patients completed combination treatment. The median ratios of postoperative PGA spacer volume to the pretreatment volume were 96.9%, 87.7%, and 74.6% at weeks 2, 4, and 8, respectively. The spacer volume was maintained at 80% at 7 weeks and was predicted to be 50% at 15 weeks and 20% in 24 weeks. CONCLUSIONS Spacer placement surgery using the PGA spacer was feasible and tolerable. The PGA spacers maintained sufficient thickness during the duration of subsequent particle therapy. Combination treatment using the PGA spacer is innovative and has the potential to become a new standard curative local treatment.
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Affiliation(s)
- Shohei Komatsu
- From the Department of Surgery, Divisions of Hepato-Biliary-Pancreatic Surgery (Komatsu, Fukumoto), Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Tianyuan Wang
- Departments of Radiation Physics (Wang, Suga), Hyogo Ion Beam Medical Center, Tatsuno, Hyogo, Japan
| | - Kazuki Terashima
- Radiology (Terashima, Demizu, Okimoto), Hyogo Ion Beam Medical Center, Tatsuno, Hyogo, Japan
| | - Yusuke Demizu
- Radiology (Terashima, Demizu, Okimoto), Hyogo Ion Beam Medical Center, Tatsuno, Hyogo, Japan
- Departments of Radiation Oncology (Demizu), Hyogo Ion Beam Medical Center Kobe Proton Center, Kobe, Hyogo, Japan
| | - Makoto Anzai
- Osaka Heavy Ion Therapy Center, Osaka, Japan (Anzai, Suzuki)
| | - Masaki Suga
- Departments of Radiation Physics (Wang, Suga), Hyogo Ion Beam Medical Center, Tatsuno, Hyogo, Japan
| | - Tomohiro Yamashita
- Radiation Physics (Yamashita), Hyogo Ion Beam Medical Center Kobe Proton Center, Kobe, Hyogo, Japan
| | - Osamu Suzuki
- Osaka Heavy Ion Therapy Center, Osaka, Japan (Anzai, Suzuki)
| | - Tomoaki Okimoto
- Radiology (Terashima, Demizu, Okimoto), Hyogo Ion Beam Medical Center, Tatsuno, Hyogo, Japan
| | - Ryohei Sasaki
- Radiation Oncology (Sasaki), Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
| | - Takumi Fukumoto
- From the Department of Surgery, Divisions of Hepato-Biliary-Pancreatic Surgery (Komatsu, Fukumoto), Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
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Sakuramachi M, Murakami N, Nagao A, Kojima K, Miyata Y, Kashihara T, Kaneda T, Takahashi K, Inaba K, Okuma K, Nakayama Y, Okamoto H, Ishikawa M, Igaki H. Hydrogel spacer injection to the meso-sigmoid to protect the sigmoid colon in cervical cancer brachytherapy: A technical report. J Contemp Brachytherapy 2023; 15:465-469. [PMID: 38230404 PMCID: PMC10789158 DOI: 10.5114/jcb.2023.134174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 12/17/2023] [Indexed: 01/18/2024] Open
Abstract
Purpose The use of a hydrogel spacer inserted into recto-vaginal fossa is a valuable strategy to mitigate radiation exposure to the rectum during radiation therapy for female pelvic malignancies. However, when the sigmoid colon is in proximity to the cervix, radiation exposure to the sigmoid colon cannot be adequately mitigated with a hydrogel spacer injected into the recto-vaginal fossa. Here, we presented a case, in which a hydrogel spacer was injected into the meso-sigmoid to protect the sigmoid colon. Material and methods A 73-year-old female diagnosed with T3b stage IIIC2r uterine cervical cancer (FIGO 2018) underwent high-dose-rate interstitial brachytherapy consisting of 24 Gy in 4 fractions, following concurrent chemoradiotherapy with external beam radiation therapy of 50 Gy in 25 fractions of whole pelvic radiation therapy. In the initial brachytherapy, the sigmoid colon was in close contact with the uterine cervix. In the second brachytherapy, attempts to create a space between the sigmoid colon and uterine cervix using injected artificial ascites were unsuccessful due to rapid absorption of fluid. In the third and fourth brachytherapy fractions, 5 mL of hydrogel was injected into the meso-sigmoid through a pouch of Douglas under trans-rectal ultrasonography guidance. Dose ratio of sigmoid colon D2cc and high-risk clinical target volume (HR-CTV) D90 of each brachytherapy were evaluated. Results Dose ratio of the sigmoid colon D2cc to HR-CTV D90 was 1.03, 0.43, 0.56, and 0.47 in each respective brachytherapy session, indicating dose escalation to HR-CTV whilst achieving acceptable sigmoid dose with hydrogel spacer injected into the meso-sigmoid. Conclusions The dose ratio of the sigmoid colon to HR-CTV D90 was decreased by introducing a hydrogel spacer into the meso-sigmoid. In cases where the sigmoid colon is in proximity to the cervical tumor, this novel technique can be considered to achieve better clinical outcomes.
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Affiliation(s)
- Madoka Sakuramachi
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Naoya Murakami
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
- Department of Radiation Oncology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Ayaka Nagao
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Kanako Kojima
- Department of Radiation Oncology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yusaku Miyata
- Department of Radiology, Kurume University School of Medicine, Fukuoka, Japan
| | - Tairo Kashihara
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Tomoya Kaneda
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Kana Takahashi
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Koji Inaba
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Kae Okuma
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Yuko Nakayama
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
| | - Hiroyuki Okamoto
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, Japan
| | - Mitsuya Ishikawa
- Department of Gynecology, National Cancer Center Hospital, Tokyo, Japan
| | - Hiroshi Igaki
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
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Muramoto Y, Murakami N, Karino T, Sugimoto S, Takatsu J, Oshima M, Kosugi Y, Kawamoto T, Hirayama T, Fujino K, Terao Y, Shikama N. MucoUp® as a spacer in brachytherapy for uterine cervical cancer: A first-in-human experience. Clin Transl Radiat Oncol 2023; 42:100659. [PMID: 37519921 PMCID: PMC10372547 DOI: 10.1016/j.ctro.2023.100659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 07/03/2023] [Accepted: 07/14/2023] [Indexed: 08/01/2023] Open
Abstract
We first used MucoUp®, a hyaluronic acid used in endoscopic resection, as a spacer in brachytherapy. In five cervical cancer patients, MucoUp® insertion increased a 90% dose of the high-risk CTV to over 80 Gy while decreasing the dose of organs at risk. No related adverse events were observed.
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Affiliation(s)
- Yoichi Muramoto
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Naoya Murakami
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Tatsuki Karino
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Satoru Sugimoto
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Jun Takatsu
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Masaki Oshima
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Yasuo Kosugi
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Terufumi Kawamoto
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Takashi Hirayama
- Department of Obstetrics and Gynecology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Kazunari Fujino
- Department of Obstetrics and Gynecology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Yasuhisa Terao
- Department of Obstetrics and Gynecology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
| | - Naoto Shikama
- Department of Radiation Oncology, Juntendo University Hospital, 3-1-3 Hongo, Bunkyo-ku, Tokyo 113-8431, Japan
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Shiba S, Okamoto M, Sakai M, Ohno T. Visualizing Bioabsorbable Spacer Effectiveness by Confirming the Distal-Tail of Carbon-Ion Beams: First-In-Human Report. Tomography 2022; 8:2339-2346. [PMID: 36287794 PMCID: PMC9610790 DOI: 10.3390/tomography8050195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 01/01/2023] Open
Abstract
In particle therapy, bioabsorbable polyglycolic acid (PGA) spacer was developed to reduce the healthy organ irradiation dose, especially in the gastrointestinal tract. The PGA spacer is safe and effective; however, there are no reports that have confirmed whether the PGA spacer which inserted in the body actually stops the carbon-ion (C-ion) beams. Here, we visualized and confirmed that the PGA spacer stops the C-ion beams in the body based on the dose distribution using auto-activation positron emission tomography (AAPET). A 59-year-old dedifferentiated retroperitoneal liposarcoma patient underwent C-ion radiotherapy (C-ion RT) on referral. A month before C-ion RT initiation, the patient underwent PGA spacer placement. Postoperatively, the patient received 4.4 Gy (RBE) per fraction of C-ion RT, followed by AAPET. AAPET revealed lower positron emitter concentrations at the distal tissue ventral to the PGA spacer than in the planning target volume. In observing the efficacy of the PGA spacer, the AAPET images and the average count per second of the positron emitter suggested that the PGA spacer stopped the C-ion beams in the body in accordance with the dose distribution. Therefore, AAPET was useful in confirming the PGA spacer's effectiveness in this study, and the PGA spacer stopped the C-ion beams.
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Affiliation(s)
- Shintaro Shiba
- Department of Radiation Oncology, Shonan Kamakura General Hospital, 1370-1, Okamoto, Kamakura-City 247-8533, Kanagawa, Japan
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22, Showa-Machi, Maebashi-City 371-8511, Gunma, Japan
- Correspondence: ; Tel.: +81-467-46-1717
| | - Masahiko Okamoto
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22, Showa-Machi, Maebashi-City 371-8511, Gunma, Japan
| | - Makoto Sakai
- Gunma University Heavy Ion Medical Center, 3-39-22, Showa-Machi, Maebashi-City 371-8511, Gunma, Japan
| | - Tatsuya Ohno
- Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22, Showa-Machi, Maebashi-City 371-8511, Gunma, Japan
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