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Dive into the research topics where Ryuji Mikami is active.

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Featured researches published by Ryuji Mikami.


British Journal of Radiology | 2015

Patients with severe emphysema have a low risk of radiation pneumonitis following stereotactic body radiotherapy.

M Ishijima; H. Nakayama; Tomohiro Itonaga; Yu Tajima; S. Shiraishi; Mitsuru Okubo; Ryuji Mikami; Koichi Tokuuye

OBJECTIVE To evaluate the risk of radiation pneumonitis (RP) after stereotactic radiotherapy (SBRT) for patients presenting with severe pulmonary emphysema. METHODS This study included 40 patients with Stage I non-small-cell lung cancer who underwent SBRT, 75 Gy given in 30 fractions, at the Tokyo Medical University, Tokyo, Japan, between February 2010 and February 2013. The median age of the patients was 79 years (range, 49-90 years), and the male:female ratio was 24:16. There were 20 T1 and 20 T2 tumours. 17 patients had emphysema, 6 had slight interstitial changes on CT images and the remaining 17 had no underlying lung disease. The level of emphysema was classified into three groups according to the modified Goddards criteria (severe: three patients, moderate: eight patients and mild: six patients). Changes in the irradiated lung following SBRT were evaluated by CT. RESULTS On CT images, RP was detected in 34 (85%) patients, and not in 6 (15%) patients, during a median observation period of 313 days. Of the six patients, three had severe emphysema and three had no underlying lung disease. Patients with severe emphysema had lower risk of RP than those with moderate emphysema (p = 0.01), mild emphysema (p = 0.04) and no underlying lung disease (p = 0.01). CONCLUSION Patients with severe emphysema had a low risk of RP following SBRT. ADVANCES IN KNOWLEDGE Little is known about the association between RP and pulmonary emphysema. Patients with severe emphysema had lower risk of RP than those with no underlying lung disease.


International Journal of Radiation Oncology Biology Physics | 2012

Preliminary Results of Fractionated Stereotactic Radiotherapy After Cyst Drainage for Craniopharyngioma in Adults

Naoto Kanesaka; Ryuji Mikami; Hidetsugu Nakayama; Sachika Nogi; Yu Tajima; Nobuyuki Nakajima; Jun Wada; Tamotsu Miki; Jou Haraoka; Mitsuru Okubo; Shinji Sugahara; Koichi Tokuuye

PURPOSE To retrospectively evaluate the effectiveness of fractionated stereotactic radiotherapy (FSRT) for craniopharyngioma. METHODS AND MATERIALS Between 1999 and 2005, 16 patients with craniopharyngioma were referred to Tokyo Medical University Hospital. They received FSRT alone after histologic confirmation by needle biopsy and underwent cyst drainage via endoscopy. The median prescription dose fraction was 30 Gy in six fractions. All patients except 1 were followed up until December 2009 or death. RESULTS The median follow-up period was 52 months (range, 4-117 months). Of the 17 patients, 3 experienced recurrence 4 to 71 months after FSRT. The 3-year local control rate was 82.4%. One patient died of thyroid cancer, and the 3-year survival rate was 94.1%. Eight patients had improved visual fields at a median of 2.5 months after FSRT, but hormonal functions did not improve in any patient. CONCLUSIONS FSRT after cyst drainage seems to be safe and effective for patients with craniopharyngiomas, and it may be a safe alternative to surgery.


British Journal of Radiology | 2015

Dosimetric evaluation of compensator intensity modulation-based stereotactic body radiotherapy for Stage I non-small-cell lung cancer

Yu Tajima; H. Nakayama; Tomohiro Itonaga; S. Shiraishi; Mitsuru Okubo; Ryuji Mikami; Shinji Sugahara; Koichi Tokuuye

OBJECTIVE To evaluate the dosimetry of compensator intensity modulation-based stereotactic body radiotherapy (SBRT) [non-coplanar intensity-modulated radiotherapy (ncIMRT)], its use was compared with that of three-dimensional conformation-based SBRT, for patients with Stage I non-small-cell lung cancer (NSCLC). METHODS 21 consecutive patients with Stage I NSCLC were treated with ncIMRT or SBRT at Tokyo Medical University. To compare the two techniques, ncIMRT and SBRT plans for each patient were generated, where the planning target volume (PTV) coverages were adjusted to be equivalent to each other. The prescribed dose was set as 75 Gy in 30 fractions. PTV coverage, conformity index, conformation number (CN) and homogeneity index (HI) were used to compare the two strategies. RESULTS There was no statistically significant difference between PTV coverage for the 100%, 95% and 90% dose levels in the SBRT plan and those in the ncIMRT plan. The CN values were 0.53 ± 0.13 in the SBRT plan and 0.72 ± 0.10 in the ncIMRT plan. These values were significantly better than those of the SBRT plan (p < 0.001). The HI in the ncIMRT plan was 1.04 ± 0.03%, which was also significantly better than that of SBRT. CONCLUSION The ncIMRT plan provided superior conformity and reduced the doses to the lung for patients with Stage I NSCLC. ADVANCES IN KNOWLEDGE The delivery technique with compensator intensity modulation-based SBRT was evaluated. Concerning target motion, this is thought to be more robust and safer than SBRT for early-stage NSCLC.


Onkologie | 2014

Radiotherapy in patients with extramammary Paget's disease--our own experience and review of the literature.

Tomohiro Itonaga; Hidetsugu Nakayama; Mitsuru Okubo; Ryuji Mikami; Sachica Nogi; Yu Tajima; Shinji Sugahara; Koichi Tokuuye

Background: There are few reports on radiotherapy methods for treating extramammary Pagets disease (EMPD). The aim of this study was to explore the outcome of radiotherapy for EMPD. Patients and Methods: Between June 1995 and October 2010, 14 patients with EMPD (7 male and 7 female; median age 77 years) underwent radiotherapy at the Tokyo Medical University Hospital. The median total irradiation dose was 50 Gy, delivered in 20-33 fractions. Case reports of patients with EMPD were obtained from the PubMed database for the period of 1991-2012. 66 patients (median age 73 years) were identified. Radiotherapy outcomes were analyzed. Results: All patients achieved complete response within the irradiated volume during a median observation period of 71.4 months. The 5-year locoregional progression-free survival and overall survival were 91.7% (95% confidence interval (CI) 53.9-98.8%) and 84.3% (95% CI 50.3-95.8%), respectively. From the PubMed database, the 5-year local progression-free survival and locoregional progression-free survival were 84.5% (95% CI 65.3-93.6%) and 77.5% (95% CI 57.3-89.0%), respectively. 12 (18%) patients had a recurrence in the inguinal lymph nodes. Conclusion: Radiotherapy yielded good local control and survival, which suggests that it was effective for patients with EMPD and in particular medically inoperable EMPD.


British Journal of Radiology | 2017

Predicting risk factors for radiation pneumonitis after stereotactic body radiation therapy for primary or metastatic lung tumours

Mitsuru Okubo; Tomohiro Itonaga; Tatsuhiko Saito; S. Shiraishi; Ryuji Mikami; H. Nakayama; Akira Sakurada; Shinji Sugahara; Kiyoshi Koizumi; Koichi Tokuuye

OBJECTIVE To investigate risk factors for radiation-induced pneumonitis (RP) after hypofractionated stereotactic body radiotherapy (SBRT) in patients with lung tumours. METHODS From May 2004 to January 2016, 66 patients with 71 primary or metastatic lung tumours were treated with SBRT; these 71 cases were retrospectively analyzed for RP. To explore the risk factors for RP, the following factors were investigated: age, sex, performance status, operability, number of treatments, respiratory gating, pulmonary emphysema, tumour location and subclinical interstitial lung disease (ILD). Irradiated underlying lung volumes of more than 5 Gy, 10 Gy, 20 Gy and 30 Gy (Lung V5, V10, V20 and V30), mean lung dose and volumes of gross tumour volume (in cubic centimetre) and planning target volume were calculated for possible risk factors of RP. RESULTS The median follow-up period was 32 months. RP of Grade 2 or more, according to the Common Terminology Criteria for Adverse Events v. 4.0, was detected in 6 (8.4%) of the 71 cases. Grade 5 RP was identified in two cases. Of the risk factors of RP, subclinical ILD was the only factor significantly associated with the occurrence of RP of Grade 2 or more (p < 0.001). Both cases with Grade 5 RP had ILD with a honeycombing image. CONCLUSION Subclinical ILD was the only significant factor for Grade 2-5 RP. In addition, the cases with honeycombing had a high potential for fatality related to severe RP. Patients with subclinical ILD should be carefully monitored for the occurrence of severe RP after SBRT. Advances in knowledge: Hypofractionated SBRT for primary or metastatic lung tumours provides a high local control rate and safe treatment.


Leukemia & Lymphoma | 2013

Preliminary results of radiotherapy for primary intraocular non-Hodgkin lymphoma

Ryuji Mikami; Hidetsugu Nakayama; Hiroshi Goto; Keisuke Kimura; Yoshihiko Usui; Sachika Nogi; Yu Tajima; Mitsuru Okubo; Naoto Kanesaka; Shinji Sugahara; Koichi Tokuuye

Abstract This study aimed to retrospectively evaluate the efficacy of radiotherapy for primary intraocular non-Hodgkin lymphoma (PIOL). Between May 1998 and October 2010, 22 immunocompetent patients (four men, 18 women; median age 70 years, range 53–79 years) were diagnosed with PIOL. Magnetic resonance imaging showed no intracranial involvement in any patient. Patients received radiotherapy at a median total dose of 30 Gy (range 30–40 Gy). Three-year overall survival, progression-free survival and local control rates were 89% (95% confidence interval [CI]: 75, 103), 49% (95% CI: 24, 73) and 95% (95% CI: 86, 105) over a median of 36 months of observation, respectively. Twelve patients (55%) had intracranial relapse at a median of 28 months after initiation of radiotherapy. Visual acuity improved or was stable in 81% of treated eyes. The only grade ≥ 3 toxicity was cataract formation (five patients). Radiotherapy without chemotherapy for PIOL achieved high local control rates with acceptable toxicities.


Oncology Letters | 2014

Cryptogenic organizing pneumonia associated with radiation: A report of two cases

Sachika Nogi; Hidetsugu Nakayama; Yu Tajima; Mitsuru Okubo; Ryuji Mikami; Shinji Sugahara; Soichi Akata; Koichi Tokuuye

Cryptogenic organizing pneumonia (COP) following radiotherapy is occasionally diagnosed as radiation pneumonitis or bacterial pneumonia. The current study presents two cases of COP following radiotherapy: A 48-year-old premenopausal female with breast cancer and an 84-year-old male with non-small cell lung cancer. In the cases of breast cancer and lung cancer, patients were first diagnosed with bacterial pneumonia and radiation pneumonitis, respectively. In the two cases, computed tomography disclosed the migration of ground glass shadows, which were finally resolved without any fibrotic changes. The two cases were finally diagnosed as COP associated with radiotherapy. When an infiltrating shadow is present outside of the irradiated field, COP must be included in the differential diagnosis.


Breast Cancer | 2017

Objection to postoperative radiation therapy in breast cancer with one to three lymph nodes involvements

Takashi Ishikawa; Hiroshi Kaise; Kimito Yamada; Mari Hosonaga; Takashi Chishima; Kazutaka Narui; Akimitsu Yamada; Sadatoshi Sugae; Yasushi Ichikawa; Mitsuyoshi Ota; Miyako Nozaki; Ryuji Mikami; Koichi Tokuuye

My arguments regarding postmastectomy radiotherapy (PMRT) for this case are based on the following 4 reasons: (1) high rate of local recurrence in the no PMRT group in the Early Breast Cancer Trialists’ Collaborative Group meta-analysis on which the present guideline is based, (2) stage migration by sentinel node biopsy, (3) possible adverse events of radiotherapy, and (4) problems on extrapolation of data from western countries.


Japanese Journal of Radiology | 2011

Selective intraarterial chemoradiation therapy for oropharyngeal carcinoma with high-dose cisplatin

Ryota Nishio; Kazuhiro Saito; Hiroyuki Ito; Tomoyuki Yoshida; Koichi Kitamura; Akira Shimizu; Naoto Kanesaka; Ryuji Mikami; Daisuke Hasegawa; Mamoru Suzuki; Koichi Tokuuye

PurposeCisplatin has shown a high tumor response rate among head and neck carcinomas, and the tumor response is related to the cisplatin dosage. The purpose of this study was to evaluate the efficacy and toxicity of selective intraarterial chemoradiation therapy for oropharyngeal carcinomas with high-dose cisplatin.Materials and methodsThis retrospective study consisted of 21 patients with oropharyngeal carcinoma, stages II-IVB, in whom intraarterial chemoradiation therapy was performed between 2000 and 2008. All patients were given two courses of selective intraarterial infusions of cisplatin (300 mg/m2), systemic chemotherapy with 5-fluorouracil, and simultaneous radiation therapy (58–61 Gy/30 fractions), with a 1-week rest period.ResultsThe 2-year overall survival rate of the 15 patients who completed the therapeutic regimen was 71.3%. The 2-year locoregional control rate and disease-free survival rate were 95.0% and 67.7%, respectively.ConclusionSelective intraarterial high-dose cisplatin chemotherapy with concomitant radiation therapy shows results similar to those of original methods in terms of survival and locoregional control with a reduction in the number of procedure times.


Magnetic Resonance in Medical Sciences | 2005

Gd-EOB-DTPA Enhanced MRI for Hepatocellular Carcinoma: Quantitative Evaluation of Tumor Enhancement in Hepatobiliary Phase

Kazuhiro Saito; Fumio Kotake; Naoki Ito; Taizo Ozuki; Ryuji Mikami; Kimihiko Abe; Yoko Shimazaki

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Koichi Tokuuye

Tokyo Medical University

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Mitsuru Okubo

Tokyo Medical University

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Yu Tajima

Tokyo Medical University

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H. Nakayama

Tokyo Medical University

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Naoto Kanesaka

Tokyo Medical University

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Sachika Nogi

Tokyo Medical University

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S. Shiraishi

Tokyo Medical University

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