Details of a Researcher - Shigematsu, Naoyuki

Papers - Shigematsu, Naoyuki

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Nationwide Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS): first analysis on survival

Ito K., Saito S., Yorozu A., Kojima S., Kikuchi T., Higashide S., Aoki M., Koga H., Satoh T., Ohashi T., Nakamura K., Katayama N., Tanaka N., Nakano M., Shigematsu N., Dokiya T., Fukushima M., Takahashi Y., Tsukiyama I., Nasu Y., Harada M., Fukagai T., Yamashita T., Matsubara A., Igawa M., Egawa S., Kakehi Y., Katsuoka Y., Kanetake H., Kubota Y., Kumon H., Yamasaki I., Suzuki K., Deguchi T., Ueno M., Naito S., Namiki M., Baba S., Hayakawa K., Hirao Y., Fujioka T., Horie S., Miki T., Murai M., Yoshida H., Itami J., Inoue T., Imai Y., Kataoka M., Kubo A., Shibuya H., Nishio M., Tanaka H., Tanaka Y., Teramukai S., Harada C., Yamashiro K., Kiba T., Kitagawa S., Uno E., Nishimura T., Kinoshita F., Iida S., Maruo S., Miyakoda K., Daimon T., Kawamoto A., Kaneda H., Yoshidomi M., Nishiyama T., Yagi Y., Namitome R., Toya K., Koike N., Yoshida K., Tabata K., Tsumura H., Kimura M., Ishiyama H., Kotani S., Kondo H., Fujimoto K., Hasegawa M., Tamamoto T., Asakawa I., Nishizawa S., Hashida I., Takezawa Y., Harada K., Tanji S., Sato K., Matsuura T., Ariga H., Ehara S., Nakamura R., Hayashi S., Ohtakara K., Kihara K., Hayashi K., Okamoto K.

International Journal of Clinical Oncology (International Journal of Clinical Oncology) 23 ( 6 ) 1148 - 1159 2018.12

ISSN 13419625

© 2018, Japan Society of Clinical Oncology. Background: Investigating oncological outcomes in patients registered in the Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS) in terms of biochemical relapse-free survival (bRFS) by the Phoenix and the newly developed J-POPS definitions, exploration of predictive factors for bRFS, and preliminary verification of pitfalls of prostate-specific antigen (PSA) failure definitions. Methods: Between July 2005 and June 2007, 2316 clinically localized patients underwent permanent seed implantation. The primary endpoint was bRFS. One of the secondary endpoints was overall survival (OS). Results: The median age was 69 and performance status was 0 in 99.1% of participants. The median biologically effective dose (BED) was about 180 Gy 2 . During a median follow-up of 60.0 months, 8.4 and 5.9% had PSA failure by the Phoenix and the J-POPS definitions, respectively. The 5-year bRFSs based on the Phoenix and the J-POPS definitions were 89.1 and 91.6%, respectively. The 5-year OS was 97.3%. According to multivariate analyses, only age affected bRFS based on the Phoenix definition, whereas the risk group and BED independently affected bRFS based on the J-POPS definition. A spontaneous PSA decrease was seen in 91.1% of participants after PSA failure based on the Phoenix definition alone, but in only 22.2% after PSA failure based on the J-POPS definition alone. Conclusion: The world’s largest registration study, J-POPS, consisted of patients with longevity, and a highly quality-controlled BED resulted in excellent bRFS and OS. The high likelihood of PSA bounce by the Phoenix definition should be taken into account, especially in younger patients. Clinical trial information: NCT00534196.

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A Highly Advanced Gastric Cancer Maintaining a Clinical Complete Response after Chemoradiotherapy Comprising S-1 and Cisplatin

Yura M., Takahashi T., Fukuda K., Nakamura R., Wada N., Fukada J., Kawakubo H., Takeuchi H., Shigematsu N., Kitagawa Y.

Case Reports in Gastroenterology (Case Reports in Gastroenterology) 12 ( 3 ) 578 - 585 2018.09

© 2018 The Author(s). Published by S. Karger AG, Basel. We report a patient with highly advanced gastric carcinoma who was treated successfully with chemoradiotherapy (CRT) comprising S-1 and cisplatin. The patient was a 71-year-old male who was diagnosed with advanced gastric carcinoma by esophagogastroduodenoscopy (EGD) by medical examination. EGD demonstrated type 3 advanced gastric carcinoma in the posterior wall of the upper gastric body. An abdominal computed tomography (CT) scan showed that the gastric wall was thickened due to gastric primary tumor, and large lymph nodes (LNs) including the lesser curvature LN, anterosuperior LN along the common hepatic artery and some para-aortic LNs were detected. The patient was diagnosed with stage IV advanced gastric carcinoma according to the Japanese classification of gastric carcinoma (cT4a, cN3, cM1 [para-aortic LN], cStage IV). Preoperative CRT was carried out in an attempt to downstage the disease. Remarkable reduction of the primary tumor and metastatic LNs was observed after initial CRT, and radiological examination determined that a partial response had been achieved. Adverse effects included grade 2 anorexia and grade 3 ALP elevation (919 U/ml). No grade 4 or more severe adverse event was observed. After CRT, although we recommended curative surgery, the patient refused surgical treatment and opted for conservative treatment. Thus, we continued S-1 oral administration for 1 year. Five months after beginning CRT, upper endoscopy showed that the tumor had maintained regression and scar formation, in which no cancer cells were detected by endoscopic biopsy. The patient is doing well and has maintained a clinical complete response for more than 42 months without curative surgery. CRT could be considered as an option for treatment of patients with locally advanced gastric carcinoma diagnosed as unresectable, or for those who refuse surgical treatment.

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Nationwide Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS)

Ito Kazuto, Saito Shiro, Yorozu Atsunori, Kojima Shinsuke, Kikuchi Takashi, Higashide Satoshi, Aoki Manabu, Koga Hirofumi, Satoh Takefumi, Ohashi Toshio, Nakamura Katsumasa, Katayama Norihisa, Tanaka Nobumichi, Nakano Masahiro, Shigematsu Naoyuki, Dokiya Takushi, Fukushima Masanori, Takahashi Yutaka, Tsukiyama Iwao, Nasu Yasutomo, Harada Masaoki, Fukagai Takashi, Yamashita Takashi, Matsubara Akio, Igawa Mikio, Egawa Shin, Kakehi Yoshiyuki, Katsuoka Youji, Kanetake Hiroshi, Kubota Yoshinobu, Kumon Hiromi, Yamasaki Ichiro, Suzuki Kazuhiro, Deguchi Takashi, Ueno Munehisa, Naito Seiji, Namiki Mikio, Baba Shiro, Hayakawa Kazushige, Hirao Yoshihiko, Fujioka Tomoaki, Horie Shigeo, Miki Tsuneharu, Murai Masaru, Yoshida Hideki, Itami Jun, Inoue Toshihiko, Imai Yutaka, Kataoka Masaaki, Koike Naoyoshi

International Journal of Clinical Oncology 1 - 12 2018.06

ISSN 1341-9625

Background: Investigating oncological outcomes in patients registered in the Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS) in terms of biochemical relapse-free survival (bRFS) by the Phoenix and the newly developed J-POPS definitions, exploration of predictive factors for bRFS, and preliminary verification of pitfalls of prostate-specific antigen (PSA) failure definitions. Methods: Between July 2005 and June 2007, 2316 clinically localized patients underwent permanent seed implantation. The primary endpoint was bRFS. One of the secondary endpoints was overall survival (OS). Results: The median age was 69 and performance status was 0 in 99.1% of participants. The median biologically effective dose (BED) was about 180 Gy². During a median follow-up of 60.0 months, 8.4 and 5.9% had PSA failure by the Phoenix and the J-POPS definitions, respectively. The 5-year bRFSs based on the Phoenix and the J-POPS definitions were 89.1 and 91.6%, respectively. The 5-year OS was 97.3%. According to multivariate analyses, only age affected bRFS based on the Phoenix definition, whereas the risk group and BED independently affected bRFS based on the J-POPS definition. A spontaneous PSA decrease was seen in 91.1% of participants after PSA failure based on the Phoenix definition alone, but in only 22.2% after PSA failure based on the J-POPS definition alone. Conclusion: The world’s largest registration study, J-POPS, consisted of patients with longevity, and a highly quality-controlled BED resulted in excellent bRFS and OS. The high likelihood of PSA bounce by the Phoenix definition should be taken into account, especially in younger patients. Clinical trial information: NCT00534196.

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Influence of backscatter radiation on cranial bone fixation devices

Sakamoto Yoshiaki, Koike Naoyoshi, Takei Hideyuki, Ohno Mari, Shigematsu Naoyuki, Kishi Kazuo

Journal of Craniofacial Surgery (Journal of Craniofacial Surgery) 29 ( 4 ) 1094 - 1096 2018.06

ISSN 1049-2275

Postoperative radiation can cause ulcer formation, leading to the denudation of skin over alloplastic materials. The influence of backscatter radiation from fixation devices has not been investigated. The aim of this study is to evaluate backscatter dose variations for different cranial bone fixation devices in an experimental model designed to simulate postoperative radiotherapy. The authors assessed the radiation backscatter doses associated with resorbable (PLLA-PGA) and titanium plates. The samples were irradiated with 6 and 10 MV photon beams from a linear accelerator. Measurements were obtained using an ionization chamber and radiochromic films cut from the same batch. As a result, the backscatter radiation of water and PLLA-PGA proportionally decreased as the depth increased. However, the backscatter radiation of the titanium plate increased just above the plate. This depth lies in the region of the scalp. Each material showed a dose of radioactivity that was higher at 10 MV than that at 6 MV. These devices showed a significant difference, which suggested that these materials amplified the dose compared with water at 6 MV. In conclusion, it is supposed that PLLA-PGA should be used to fix the cranium to decrease the potential for radiation ulcers.

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Long-term results of concurrent chemoradiotherapy with daily-low-dose continuous infusion of 5-fluorouracil and cisplatin (LDFP) for Stage I-II esophageal carcinoma

Kumabe A., Fukada Junichi, Kota R., Koike N., Shiraishi Y., Seki S., Yoshida K., Kitagawa Y., Shigematsu N.

Diseases of the Esophagus (Diseases of the Esophagus) 31 ( 4 ) 2018.04

ISSN 1120-8694

We investigated long-term treatment outcomes and the feasibility of chemoradiotherapy consisting of daily-low-dose 5-fluorouracil and cisplatin (LDFP) chemotherapy plus radiotherapy for Stage I-II squamous cell esophageal cancer. Treatment records from the 2000 through 2008 period were reviewed retrospectively. Fractionated radiotherapy was performed with a total dose of 60 Gy delivered in 2 Gy per fraction. LDFP chemotherapy, as continuous infusion of 200 mg/m² 5-fluorouracil combined with one hour infusion of 4 mg/m² cisplatin, was administered on the same days as radiotherapy. Survival was calculated by the Kaplan-Meier method. Survival, responses, failure patterns, and toxicities were evaluated. Seventy-six (47 stage I and 29 stage II) patients were analyzed with a median follow-up of 93.6 months. The 8-year overall survival (OS), progression-free survival (PFS) and cause-specific survival (CSS) rates were 63.4%, 49.8%, and 76.7%, respectively. The 8-year OS, PFS, and CSS for stage I and stage II patients were 71.0%/56.1%/82.9% and 45.2%/40.2%/66.6%, respectively. Sixty-eight patients (89.5%) completed the treatment regimen. A complete response (CR) was achieved in 68 patients (89.5%). Twenty-five patients (36.8%) experienced recurrence after CR. The failure patterns were (overlap included): local failure (n = 12), nodal metastasis (n = 12), distant metastasis (n = 3), details unknown (n = 2). Salvage therapy was performed for local failure; endoscopic therapy (n = 7) or surgery (n = 2). Six patients remain alive without relapse after salvage endoscopic therapy. Major Grade 3 or higher acute adverse events were leukopenia (22%), anorexia (17%), and esophagitis (11%). Major late toxicities (Grade 3 or 4) involved pericardial effusion (12%), pleural effusion (4%), and esophageal stenosis (3%). Chemoradiotherapy with LDFP provided favorable long-term survival with acceptable toxicity for Stage I-II squamous cell esophageal cancer. The tumor response was excellent, but close endoscopic follow-up is essential for detecting and treating local recurrence.

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Predictive factors of long-term rectal toxicity following permanent iodine-125 prostate brachytherapy with or without supplemental external beam radiation therapy in 2216 patients

Tanaka Tomoki, Yorozu Atsunori, Sutani Shinya, Yagi Yasuto, Nishiyama Toru, Shiraishi Yutaka, Ohashi Toshio, Hanada Takashi, Saito Shiro, Toya Kazuhito, Shigematsu Naoyuki

Brachytherapy (Brachytherapy) 17 ( 5 ) 799 - 807 2018.01

ISSN 1538-4721

Purpose: We analyzed factors associated with rectal toxicity after iodine-125 prostate brachytherapy (BT) with or without external beam radiation therapy (EBRT). Methods and Materials: In total, 2216 prostate cancer patients underwent iodine-125 BT with or without EBRT between 2003 and 2013. The median followup was 6.9 years. Cox proportional hazards modeling was used for univariate and multivariate analyses to assess clinical and dosimetric factors associated with rectal toxicity. Dosimetric parameters from 1 day after implantation (Day 1) and 1 month after implantation (Day 30) were included in the analyses. Results: The 7-year cumulative incidence of Grade 2 or higher rectal toxicity was 5.7% in all patients. The multivariate analysis revealed that antiplatelet or anticoagulant therapy, neoadjuvant androgen deprivation therapy, treatment modality, Day 1 rectal volume receiving 100% of the prescribed dose (RV₁₀₀), and the Day 30 minimal percent of the prescribed dose delivered to 30% of the rectum (RD₃₀) were associated with rectal toxicity. Day 1 RV₁₀₀ was a common predictor in both BT-alone and the BT + EBRT groups. The 5-year cumulative incidence of Grade 2 or higher rectal toxicity was 12.6%, 5.9%, and 1.7% for BT + 3-dimensional conformal radiation therapy, BT + intensity-modulated radiation therapy, and the BT-alone groups, respectively (p < 0.001). Conclusions: Rectal dosimetric parameters in BT were associated with late rectal toxicity. Although the risk of rectal toxicity was higher when EBRT was combined with BT, with proper and achievable rectal dose constraints intensity-modulated radiation therapy yielded less toxicity than 3-dimensional conformal radiation therapy.

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Prostate-specific antigen nadir within 12 months as an early surrogate marker of biochemical failure and distant metastasis after low-dose-rate brachytherapy or external beam radiotherapy for localized prostate cancer

Nishimura Shuichi, Ohashi Toshio, Momma Tetsuo, Sakayori Masanori, Eriguchi Takahisa, Tanaka Tomoki, Yamashita Shoji, Kosaka Takeo, Oya Mototsugu, Shigematsu Naoyuki

Cancer Medicine (Cancer Medicine) 7 ( 5 ) 1794 - 1801 2018.01

Prostate-specific antigen nadir (nPSA) after radiotherapy for localized prostate cancer has been investigated as a predictor. However, nPSA usually requires several years, limiting its clinical utility. We investigated the significance of nPSA within 12 months (nPSA12) after low-dose-rate prostate brachytherapy (LDR-PB) or external beam radiotherapy (EBRT) on treatment outcomes. Between 2006 and 2014, 663 patients with prostate cancer were treated with LDR-PB or EBRT at two institutions. Four hundred and seventy-four men received LDR-PB and 189 men received EBRT, without androgen deprivation therapy. The Kaplan-Meier method was used for biochemical failure (BF)-free survival (BFFS) and distant metastasis (DM)-free survival (DMFS) analyses, and multivariable Cox regression analysis was performed. The median follow-up was 61.3 months. The median nPSA12 in the LDR-PB and EBRT cohorts was 0.7 and 1.0 ng/mL, respectively. The 7-year BFFS and DMFS rates in LDR-PB patients with nPSA12 ≤ 0.7 ng/mL were 99.1% and 99.5%, respectively; when nPSA12 was >0.7 ng/mL, they were 90.2% and 94.8%, respectively. In EBRT patients with nPSA12 ≤ 1.0 ng/mL, BFFS and DMFS rates were 85.4% and 98.5%, respectively; when nPSA12 was >1.0 ng/mL, they were 67.1% and 87.2%, respectively. nPSA12 was an independent predictor of BF and DM in both cohorts (LDR-PB, P = 0.004 and 0.020, respectively; EBRT, P = 0.005 and 0.041, respectively). The nPSA12 after LDR-PB or EBRT is significantly associated with treatment outcomes of prostate cancer. Higher nPSA12 may identify patients at high risk of relapse who might benefit from salvage treatment.

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Plan reproducibility of intraoperatively custom-built linked seeds compared to loose seeds for prostate brachytherapy

Kaneda T., Ohashi T., Sakayori M., Sutani S., Yamashita S., Momma T., Takahashi S., Hanada T., Shigematsu N.

Journal of Contemporary Brachytherapy (Journal of Contemporary Brachytherapy) 10 ( 4 ) 291 - 296 2018

ISSN 1689832X

© 2018 American Public Health Association Inc. All Rights Reserved. Purpose: Few studies have compared the implant quality of linked and loose seeds for prostate brachytherapy. This study aimed to evaluate and compare plan reproducibility of intraoperatively built custom linked seeds and loose seeds for prostate brachytherapy. Material and methods: Between December 2010 and March 2014, 76 localized prostate cancer patients received Iodine-125 brachytherapy with external beam radiotherapy. Linked and loose seeds were implanted in 39 and 37 patients, respectively. The primary endpoint was the mean (± standard deviation) of the absolute change in the minimum dose received by 90% of the prostate volume between intraoperative and post-operative planning (ΔD 90 ) to confirm plan reproducibility. Comparisons between the groups were evaluated using 2-sample t tests. Results: The ΔD 90 values were 6.95 ± 11.6% and -0.41 ± 8.5% for the loose and linked seed groups, respectively (p < 0.01). The linked seed group showed decreased post-operative D 90 (118.8% vs. 127.2%), V 150 (51.7% vs. 66.7%), and RV 100 (0.44 ml vs. 0.61 ml) compared to the loose seed group (p < 0.01), whereas lung migration tended to be reduced (0% vs. 8%). Conclusions: The plan reproducibility of the linked seed group was better than that of the loose seed group. Moreover, the linked seed group showed less migration and lower rectal dose.

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Long-term clinical results of concurrent chemoradiotherapy for patients with cervical esophageal squamous cell carcinoma

Kumabe Atsuhiro, Zenda Sadatomo, Motegi Atsushi, Onozawa Masakatsu, Nakamura Naoki, Kojima Takashi, Daiko Hiroyuki, Shigematsu Naoyuki, Akimoto Tetsuo

Anticancer Research 37 ( 9 ) 5039 - 5044 2017.09

ISSN 0250-7005

Background/Aim: We assessed the efficacy and toxicity of concurrent chemoradiotherapy (CCRT) in patients with squamous cell carcinoma of the cervical esophagus. Patients and Methods: We retrospectively analyzed 37 patients treated with definitive CCRT. The patients received radiotherapy at a fraction dose of 2 Gy (total; 60 or 70 Gy) and concurrent chemotherapy. Adjuvant chemotherapy consisted of 1 to 2 cycles of 5-fluorouracil plus cisplatin or nedaplatin. Results: The median follow-up was 119.0 months, the 10-year overall survival, progression-free survival and laryngectomy-free survival rates were 35.6, 19.9 and 30.2% respectively. In the univariate analysis, T stage (T4 vs. T1-3) was the only prognostic factor for PFS. The most common acute toxicity was leukocytopenia (Grade 3; 27%). As for late toxicities, 4 patients (11%) developed Grade 2 or 3 esophageal strictures. Conclusion: The results of this study demonstrated that CCRT yielded satisfactory clinical outcomes with acceptable toxicities.

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Stereotactic body radiotherapy for operable early-stage non-small cell lung cancer

Eriguchi Takahisa, Takeda Atsuya, Sanuki Naoko, Tsurugai Yuichiro, Aoki Yousuke, Oku Yohei, Hara Yu, Akiba Takeshi, Shigematsu Naoyuki

Lung Cancer 109 62 - 67 2017.07

ISSN 0169-5002

Purpose To analyze outcomes of stereotactic body radiotherapy (SBRT) for operable patients with early-stage non-small cell lung cancer (NSCLC) and to evaluate factors associated with outcomes. Methods We retrospectively analyzed operable patients with NSCLC, staged as cT1-2N0M0, treated with SBRT between 2006 and 2015. Both biopsy-proven and clinically diagnosed NSCLC were included. Local control and survival rates were calculated and compared between subsets of patients. We investigated factors associated with outcomes. Results We identified 88 operable patients among 661 patients with cT1-2N0M0 NSCLC. The median age was 79 years (range: 55–88). The median follow-up time after SBRT was 40 months (range: 4–121). Fifty-nine patients had been pathologically diagnosed and the other 29 had been clinically diagnosed as having NSCLC. Local control, cause-specific survival (CSS) and overall survival (OS) at 3 years were 91%, 97% and 90% for T1, and 100%, 82% and 74% for T2, respectively. The CSS and OS at 3 years were 100% and 100% for GGO and 83% and 59% for solid tumors, respectively (p = 0.005). On univariate analysis, age and T stage were significantly associated with CSS, and age, the Charlson Comorbidity Index (CCI), and opacity were significantly associated with OS. On multivariate analysis, age and CCI were significantly associated with OS. As for toxicities, Grades 0, 1, 2 and 3 radiation pneumonitis occurred in 37.5%, 47.7%, 13.6% and 1.1% of patients, respectively. No Grade 4 or 5 radiation pneumonitis occurred, and no other toxicities of Grade 2 or above were observed. Conclusion Outcomes of SBRT for operable early stage NSCLC were as good as previous SBRT and surgery studies. Further investigation for selecting good SBRT candidates is warranted in high-risk operable patients.

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Quantitative analysis of genitourinary toxicity after iodine-125 brachytherapy for localized prostate cancer

Sakayori Masanori, Ohashi Toshio, Momma Tetsuo, Kaneda Tomoya, Nishimura Shuichi, Sutani Shinya, Yamashita Shoji, Shigematsu Naoyuki

Brachytherapy 2017.03

ISSN 1538-4721

Purpose: To analyze genitourinary toxicity by followup of the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) after prostate brachytherapy. Methods and Materials: Six hundred eighty patients were treated with iodine-125 brachytherapy for localized prostate cancer. IPSS, OABSS, and two categories of IPSS questions (storage symptom score [IPSS-S] and voiding symptom score [IPSS-V]) were evaluated. Results: The median followup was 54 months (range, 24-108). All scales showed rapid increases followed by gradual decreases. The median times to IPSS peak and resolution were 1 and 6 months, respectively. The resolution rates of IPSS, IPSS-S, IPSS-V, and OABSS at the last followup were 84.2%, 86.3%, 89.5%, and 83.0%, respectively. The difference between IPSS baseline and peak was greater for larger preimplant prostate volumes (≥25 mL, p = 0.004). The time to resolution was longer for higher biologic effective dose (BED) (≥210 Gy, p = 0.019 [IPSS]), in those with larger prostate volumes (≥25 mL, p = 0.025 [OABSS]), in younger patients (younger than 70 years, p = 0.043 [IPSS-S]), and in those with androgen deprivation therapy (ADT) use (p = 0.049 [IPSS-V]). Urge incontinence, included in the OABSS, was observed more commonly in older patients (75 years and older, p = 0.018), with ADT use (p < 0.001), and for higher BED (≥210 Gy, p = 0.006). Conclusions: The IPSS and OABSS showed similar patterns of change. Urinary symptoms improved more rapidly in those with high baseline IPSS levels. The OABSS was useful for following urinary symptoms after prostate brachytherapy. Age, ADT use, preimplant prostate volume, and BED were significantly associated with urinary outcomes.

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Evaluation of radiation exposure in Ir-192 brachytherapy for treatment of keloids

Ohta Mao, Nakao Noriaki, Kuribayashi Shigehiko, Miyashita Tsuguhiro, Shigematsu Naoyuki, Hayashizaki Noriyosu

Energy Procedia 131 363 - 370 2017.01

ISSN 1876-6102

Nippon Medical School Hospital recently developed a high dose rate superficial brachytherapy (HDR-SBT) for keloids, which has been carried out since 2008. In this treatment, Ir-192 sources are placed on the affected area through flexible tubes, which has the advantage of providing high dose concentration to complicated shapes. Obviously, unnecessary radiation exposure to high-energy gamma rays must be reduced for vital organs around the affected area. We have developed a system which can evaluate the radiation exposure of tissues and organs in a MIRD-5 phantom using the PHITS Monte Carlo code when the prescribed dose was delivered uniformly to a flat surface based on the actual geometry in HDR-SBT. In the PHITS simulation, an affected area was assumed on the chest of the MIRD-5 phantom, then the dwell time at each dwell position was optimized to deliver 6 Gy uniformly over the affected area in the actual geometry with the lead shields and the bolus. In addition, the radiation exposures of each tissue and organ in the MIRD-5 phantom during the irradiation were calculated. The biologically equivalent dose of the thymus was the highest at 1145.60 mGy followed by the heart at 236.14 mGy and the breasts at 95.32 mGy.

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Influence of backscatter radiation on cranial reconstruction implants

Sakamoto Yoshiaki, Koike Naoyoshi, Takei Hideyuki, Ohno Mari, Miwa Tomoru, Yoshida Kazunari, Shigematsu Naoyuki, Kishi Kazuo

British Journal of Radiology 90 ( 1070 ) 2017

ISSN 0007-1285

Objective: We aimed to evaluate backscatter dose variations in different cranial bone implant materials in an experimental model designed to simulate postoperative radiotherapy. Methods: We assessed the radiation backscatter doses associated with sheet- and mesh-type titanium plates and hydroxyapatite (HAP) samples (porosity: 35%, 50% and 85%). The samples were irradiated with 6- and 10-MV photon beams from a linear accelerator. Measurements were obtained using an ionization chamber and radiochromic films cut from the same batch. Results: At 6MV, the titanium sheet showed the highest peak for backscattered radiation, followed by (in decreasing order) HAP30%, HAP50%, titanium mesh and HAP85%. At 10MV, HAP30% showed the highest peak, followed by HAP50%, titanium sheet, titanium mesh and HAP85%. The peaks were at different depths in the titanium and HAP samples. The thickness of the human scalp is approximately 7mm; therefore, measurements were obtained 0-7mm above the implants to assess the likely dose on the scalp. A comparison of the maximum dose on the scalp showed the titanium sheet had the highest dose at both 6 and 10MV. Conclusion: The backscatter dose differed with the density of the material and the backscatter depth was different for each material. Advances in knowledge: Ulcer formation due to radiotherapy after brain tumour depends on not only radiation but also the implant material. Therefore, the density and type of implant material should be considered when planning radiotherapy and selecting bone reconstruction materials.

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Single-energy metal artifact reduction in postimplant computed tomography for I-125 prostate brachytherapy

Shiraishi Yutaka, Yamada Yoshitake, Tanaka Tomoki, Eriguchi Takahisa, Nishimura Shuichi, Yoshida Kayo, Hanada Takashi, Ohashi Toshio, Shigematsu Naoyuki, Jinzaki Masahiro

Brachytherapy 15 ( 6 ) 768 - 773 2016.11

ISSN 1538-4721

Purpose To evaluate the effectiveness of the single-energy metal artifact reduction (SEMAR) technique for improving the accuracy of I-125 seed identification in postimplant computed tomography (CT) after prostate brachytherapy. Methods and Materials Postimplant CT images of 40 patients treated with I-125 prostate brachytherapy were acquired. For all patients, 2 data sets were reconstructed, 1 with SEMAR algorithms (SEMAR image), and the other without SEMAR algorithms (non-SEMAR image). Seed locations are automatically detected by the automatic seed finder tool, and their locations were compared between the SEMAR and non-SEMAR images. Dosimetric parameters using seed locations as detected were compared. Results The true-positive fraction of properly detected seeds on the SEMAR image as determined from a reference seed distribution defined by one investigator was significantly higher than the true-positive fraction on the non-SEMAR image (p = 0.011). The variabilities in D₉₀ (p = 0.001), V₁₀₀ (p = 0.007), and V₁₅₀ (p = 0.007) were significantly reduced for seed location on the SEMAR image as compared with non-SEMAR image. Conclusions Prostate postimplant CT with SEMAR improved the accuracy of seed localization and postimplant dosimetric parameters.

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In vivo spatial correlation between ¹⁸F-BPA and ¹⁸F-FDG uptakes in head and neck cancer

Kobayashi Kazuma, Kurihara Hiroaki, Watanabe Yoshiaki, Murakami Naoya, Inaba Koji, Nakamura Satoshi, Wakita Akihisa, Okamoto Hiroyuki, Umezawa Rei, Takahashi Kana, Igaki Hiroshi, Ito Yoshinori, Yoshimoto Seiichi, Shigematsu Naoyuki, Itami Jun

Applied Radiation and Isotopes 115 138 - 146 2016.09

ISSN 0969-8043

Background and purpose Borono-2-¹⁸F-fluoro-phenylalanine (¹⁸F-BPA) has been used to estimate the therapeutic effects of boron neutron capture therapy (BNCT), while ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) is the most commonly used positron emission tomography (PET) radiopharmaceutical in a routine clinical use. The aim of the present study was to evaluate spatial correlation between ¹⁸F-BPA and ¹⁸F-FDG uptakes using a deformable image registration-based technique. Material and methods Ten patients with head and neck cancer were recruited from January 2014 to December 2014. All patients underwent whole-body ¹⁸F-BPA PET/computed tomography (CT) and ¹⁸F-FDG PET/CT within a 2-week period. For each patient, ¹⁸F-BPA PET/CT and ¹⁸F-FDG PET/CT images were aligned based on a deformable image registration framework. The voxel-by-voxel spatial correlation of standardized uptake value (SUV) within the tumor was analyzed. Results Our image processing framework achieved accurate and validated registration results for each PET/CT image. In 9/10 patients, the spatial distribution of SUVs between ¹⁸F-BPA and ¹⁸F-FDG showed a significant, positive correlation in the tumor volume. Conclusions Deformable image registration-based voxel-wise analysis demonstrated a spatial correlation between ¹⁸F-BPA and ¹⁸F-FDG uptakes in the head and neck cancer. A tumor sub-volume with a high ¹⁸F-FDG uptake may predict high accumulation of ¹⁸F-BPA.

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Stereotactic body radiotherapy for T3 and T4N0M0 non-small cell lung cancer

Eriguchi Takahisa, Takeda Atsuya, Sanuki Naoko, Nishimura Shuichi, Takagawa Yoshiaki, Enomoto Tatsuji, Saeki Noriyuki, Yashiro Kae, Mizuno Tomikazu, Aoki Yousuke, Oku Yohei, Yokosuka Tetsuya, Shigematsu Naoyuki

Journal of Radiation Research 57 ( 3 ) 265 - 272 2016.06

ISSN 0449-3060

To evaluate the outcomes and feasibility of stereotactic body radiotherapy (SBRT) for cT3 and cT4N0M0 non-small cell lung cancer (NSCLC), 25 patients with localized primary NSCLC diagnosed as cT3 or cT4N0M0, given SBRT between May 2005 and July 2013, were analyzed. All patients had inoperable tumors. The major reasons for tumors being unresectable were insufficient respiratory function for curative resection, advanced age (>80 years old) or technically inoperable due to invasion into critical organs. The median patient age was 79 years (range; 60-86). The median follow-up duration was 25 months (range: 5-100 months). The 2-year overall survival rates for T3 and T4 were 57% and 69%, respectively. The 2-year local control rates for T3 and T4 were 91% and 68%, respectively. As for toxicities, Grade 0-1, Grade 2 and Grade 3 radiation pneumonitis occurred in 23, 1 and 1 patient, respectively. No other acute or symptomatic late toxicities were reported. Thirteen patients who had no local, mediastinal or intrapulmonary progression at one year after SBRT underwent pulmonary function testing. The median variation in pre-SBRT and post-SBRT forced expiratory volume in 1 s (FEV1) values was -0.1 (-0.8-0.8). This variation was not statistically significant (P = 0.56). Forced vital capacity (FVC), vital capacity (VC), %VC and %FEV1 also showed no significant differences. SBRT for cT3 and cT4N0M0 NSCLC was both effective and feasible. Considering the favorable survival and low morbidity rate, SBRT is a potential treatment option for cT3 and cT4N0M0 NSCLC.

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Erectile function status is highly associated with prostate-specific antigen bounce in localized prostate cancer patients treated with permanent prostate brachytherapy

Matsushima Masashi, Kikuchi Eiji, Matsumoto Kazuhiro, Kosaka Takeo, Mizuno Ryuichi, Ohashi Toshio, Mikami Shuji, Miyajima Akira, Shigematsu Naoyuki, Oya Mototsugu

International Journal of Urology 23 ( 3 ) 247 - 252 2016.03

ISSN 0919-8172

Objectives: To examine the relationship between erectile function status and prostate-specific antigen bounce after prostate brachytherapy for localized prostate cancer. Methods: We identified 154 patients who were followed up for at least 24 months after brachytherapy. Erectile function status was assessed prospectively before brachytherapy (baseline), and 3, 6, 12, 18, 24 and 36 months postoperatively using the International Index of Erectile Function-15 questionnaire. Prostate-specific antigen bounce was defined as an increase of at least 0.4 ng/mL from a previous prostate-specific antigen level with a subsequent decline equal to, or less than, the initial nadir without treatment. A logistic regression analysis was used to identify a significant set of independent predictors of prostate-specific antigen bounce after brachytherapy. Results: Prostate-specific antigen bounce was observed in 38 (24.7%) men. The prostate-specific antigen bounce group had a higher erectile function domain score, higher orgasmic function domain score, and higher total International Index of Erectile Function-15 score before (at baseline) and after brachytherapy (3, 6, 12, 18, 24 and 36 months after brachytherapy) than their counterparts (P <0.05). Of the 77 patients who completed the International Index of Erectile Function-15 questionnaire 18 months after brachytherapy (the median time of prostate-specific antigen bounce), sexual desire and intercourse satisfaction domain scores, and total International Index of Erectile Function scores 18 months after brachytherapy correlated with the occurrence of prostate-specific antigen bounce. A multivariate analysis identified the intercourse satisfaction domain score 18 months after brachytherapy as an independent indicator for the occurrence of prostate-specific antigen bounce (P = 0.008). Conclusions: International Index of Erectile Function-15 score seems to be correlated with the prostate-specific antigen bounce in prostate cancer patients undergoing brachytherapy, and an occurrence of prostate-specific antigen bounce seems to be more likely in those who are more sexually active.

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Prospective study of direct radiation exposure measurements for family members living with patients with prostate ¹²⁵I seed implantation

Hanada Takashi, Yorozu Atsunori, Shinya Yukiko, Kuroiwa Nobuko, Ohashi Toshio, Saito Shiro, Shigematsu Naoyuki

Brachytherapy 2016.02

ISSN 1538-4721

Purpose: To broaden the current understanding of radiation exposure and risk and to provide concrete evidence of radiation safety related to ¹²⁵I seed implantation. Methods and Materials: Direct radiation exposure measurements were obtained from dosimeters provided to 25 patients who underwent ¹²⁵I seed implantation, along with their family members. The estimated lifetime exposure dose and the precaution time for holding children near the patient's chest were calculated in two study periods. Results: During the first and second study period, the mean estimated lifetime exposure doses were, respectively, 7.61 (range: 0.45, 20.21) mSv and 6.84 (range: 0.41, 19.20) mSv for patients, and 0.19 (range: 0.02, 0.54) mSv and 0.25 (range: 0.04, 1.00) mSv for family members. The mean ratios of first and second period measurements were 1.05 (range: 0.44, 3.18) for patients and 1.82 (range: 0.21, 7.04) for family members. The corresponding absolute differences between first and second period measurements were -0.77 (range: -11.40, 7.63) mSv and 0.06 (range: -0.26, 0.79) mSv, respectively. Assuming a dose limit of 1 mSv, the precaution times for holding a child every day of the first and second periods were 250.9 (range: 71.3, 849.4) min and 275.2 (range: 75.0, 883.4) min, respectively. Assuming a dose limit of 0.5 mSv, the corresponding precaution times were 179.0 (range: 35.6, 811.5) min and 178.9 (range: 37.5, 1131.8) min, respectively. Conclusions: Our study demonstrated low radiation exposures to family members of patients undergoing ¹²⁵I prostate implantation. It was clear that ¹²⁵I seed implantation did not pose a threat to the safety of family members.

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Dose reconstruction technique using non-rigid registration to evaluate spatial correspondence between high-dose region and late radiation toxicity

Kobayashi Kazuma, Murakami Naoya, Inaba Koji, Wakita Akihisa, Nakamura Satoshi, Okamoto Hiroyuki, Sato Jun, Umezawa Rei, Takahashi Kana, Igaki Hiroshi, Ito Yoshinori, Shigematsu Naoyuki, Itami Jun

Journal of Contemporary Brachytherapy 8 ( 2 ) 156 - 163 2016

ISSN 1689-832X

Purpose: Small organ subvolume irradiated by a high-dose has been emphasized to be associated with late complication after radiotherapy. Here, we demonstrate a potential use of surface-based, non-rigid registration to investigate how high-dose volume topographically correlates with the location of late radiation morbidity in a case of tracheobronchial radiation stenosis. Material and methods: An algorithm of point set registration was implemented to handle non-rigid registration between contour points on the organ surfaces. The framework estimated the global correspondence between the dose distribution and the varying anatomical structure. We applied it to an 80-year-old man who developed tracheobronchial stenosis 2 years after high-dose-rate endobronchial brachytherapy (HDR-EBT) (24 Gy in 6 Gy fractions) and external beam radiotherapy (EBRT) (40 Gy in 2 Gy fractions) for early-stage tracheal cancer. Results and conclusions: Based on the transformation function computed by the non-rigid registration, irradiated dose distribution was reconstructed on the surface of post-treatment tracheobronchial stenosis. For expressing the equivalent dose in a fractional dose of 2 Gy in HDR-EBT, α/β of linear quadratic model was assumed as 3 Gy for the tracheal bronchus. The tracheobronchial surface irradiated by more than 100 Gy_αβ3 tended to develop severe stenosis, which attributed to a more than 50% decrease in the luminal area. The proposed dose reconstruction technique can be a powerful tool to predict late radiation toxicity with spatial consideration.

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Dosimetric variations due to interfraction organ deformation in cervical cancer brachytherapy

Kobayashi Kazuma, Murakami Naoya, Wakita Akihisa, Nakamura Satoshi, Okamoto Hiroyuki, Umezawa Rei, Takahashi Kana, Inaba Koji, Igaki Hiroshi, Ito Yoshinori, Shigematsu Naoyuki, Itami Jun

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 117 ( 3 ) 555 - 558 2015.12

ISSN 0167-8140

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