Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Yu Tajima is active.

Publication


Featured researches published by Yu Tajima.


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.


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.


World Journal of Radiology | 2016

Diffusion-weighted imaging of the liver: Current applications

Kazuhiro Saito; Yu Tajima; Taiyo L Harada

Diffusion-weighted imaging (DWI) of the liver can be performed using most commercially available machines and is currently accepted in routine sequence. This sequence has some potential as an imaging biomarker for fibrosis, tumor detection/characterization, and following/predicting therapy. To improve reliability including accuracy and reproducibility, researchers have validated this new technique in terms of image acquisition, data sampling, and analysis. The added value of DWI in contrast-enhanced magnetic resonance imaging was established in the detection of malignant liver lesions. However, some limitations remain in terms of lesion characterization and fibrosis detection. Furthermore, the methodologies of image acquisition and data analysis have been inconsistent. Therefore, researchers should make every effort to not only improve accuracy and reproducibility but also standardize imaging parameters.


Cancer Imaging | 2017

3D analysis of apparent diffusion coefficient histograms in hepatocellular carcinoma: correlation with histological grade

Tomohisa Moriya; Kazuhiro Saito; Yu Tajima; Taiyo L Harada; Yoichi Araki; Katsutoshi Sugimoto; Koichi Tokuuye


Molecular and Clinical Oncology | 2016

Feasibility of intensity-modulated radiotherapy combined with gemcitabine and S-1 for patients with pancreatic cancer

Norifumi Kennoki; Hidetsugu Nakayama; Yuichi Nagakawa; Yuichi Hosokawa; Tomohiro Itonaga; Yu Tajima; Sachica Shiraishi; Ryuji Mikami; Akihiko Tsuchida; Koichi Tokuuye


Anticancer Research | 2013

Tumor response after low-dose preoperative radiotherapy combined with chemotherapy for squamous cell esophageal carcinoma.

Noriko Kobayashi; Hidetsugu Nakayama; Yoshiaki Osaka; Shingo Tachibana; Sachika Nogi; Yu Tajima; Mitsuru Okubo; Ryuji Mikami; Naoto Kanesaka; Shinji Sugahara; Sumito Hoshino; Akihiko Tsuchida; Koichi Tokuuye

Collaboration


Dive into the Yu Tajima's collaboration.

Top Co-Authors

Avatar

Koichi Tokuuye

Tokyo Medical University

View shared research outputs
Top Co-Authors

Avatar

Ryuji Mikami

Tokyo Medical University

View shared research outputs
Top Co-Authors

Avatar

Mitsuru Okubo

Tokyo Medical University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

H. Nakayama

Tokyo Medical University

View shared research outputs
Top Co-Authors

Avatar

Sachika Nogi

Tokyo Medical University

View shared research outputs
Top Co-Authors

Avatar

Naoto Kanesaka

Tokyo Medical University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

S. Shiraishi

Tokyo Medical University

View shared research outputs
Researchain Logo
Decentralizing Knowledge