Network


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

Hotspot


Dive into the research topics where Kei Shibuya is active.

Publication


Featured researches published by Kei Shibuya.


Japanese Journal of Clinical Oncology | 2010

Therapeutic Effect of Linac-based Stereotactic Radiotherapy with a Micro-multileaf Collimator for the Treatment of Patients with Brain Metastases from Lung Cancer

Jun-ichi Saitoh; Yoshihiro Saito; Tomoko Kazumoto; Shigehiro Kudo; Akihiro Ichikawa; Nobuaki Hayase; Kiyoshi Kazumoto; Hiroshi Sakai; Kei Shibuya

OBJECTIVE To assess the efficacy of hypofractionated linac-based stereotactic radiotherapy with a micro-multileaf collimator (mMLC) in lung cancer patients with brain metastases. METHODS Seventy-eight lesions of brain metastases in 49 lung cancer patients treated by stereotactic radiotherapy between September 2003 and December 2006 were analyzed. In the treatment planning, the planning target volume (PTV) was defined as an enhanced lesion plus 3 mm margin. A total dose of 39-42 Gy in three fractions was delivered to the isocenters of the PTV. RESULTS The median survival time after stereotactic radiotherapy was 17.4 months. The 1- and 2-year survival rates were 61% and 32%, respectively. The presence of extracranial tumors, the pre-treatment performance status, and the Radiation Therapy Oncology Group recursive partitioning analysis class were significant prognostic factors. The 1- and 2-year local recurrence rates were 14% and 17%, respectively, with no serious acute toxic effect. Injuries involving brain necrosis were observed in six patients. New brain metastases or meningeal carcinomatosis was seen in more than half of the patients following treatment with stereotactic radiotherapy. CONCLUSIONS Hypofactionated stereotactic radiotherapy with mMLC is considered to be an effective and safe modality for the treatment of brain metastases in lung cancer patients.


Journal of Radiation Research | 2014

Impact of boost irradiation on pelvic lymph node control in patients with cervical cancer.

Masaru Wakatsuki; Tatsuya Ohno; Shingo Kato; Ken Ando; Shin-ei Noda; Hiroki Kiyohara; Kei Shibuya; Kumiko Karasawa; Tadashi Kamada; Takashi Nakano

Radiation therapy (RT) for metastatic pelvic lymph nodes (PLNs) is not well established in cervical cancer. In this study the correlation between size of lymph nodes and control doses of RT was analyzed. Between January 2002 and December 2007, 245 patients with squamous cell carcinoma of the cervix treated with a combination of external beam irradiation with or without boost irradiation and high-dose rate brachytherapy were investigated. Size of lymph node was measured by computed tomography before RT and just after 50 Gy RT. Of the 245 patients, 78 had PLN metastases, and a total of 129 had enlarged PLNs diagnosed as metastases; 22 patients had PLN failure. The PLN control rate at 5 years was 79.5% for positive cases and 95.8% for negative cases. In cases with positive PLNs, 12 of 129 nodes (9.3%) developed recurrences. There was significant correlation between PLN control rate and size of PLN after 50 Gy (<10 mm: 96.7%, ≥ 10 mm: 75.7 % (P<0.001)). In addition, the recurrence in these poor-response nodes was significantly correlated with dose of RT. Nine of 16 nodes receiving ≤ 58 Gy had recurrence, but none of 21 nodes receiving > 58 Gy had recurrence (P = 0.0003). These results suggested that the response of lymph nodes after RT was a more significant predictive factor for recurrence than size of lymph node before RT, and poor-response lymph nodes might require boost irradiation at a total dose of > 58 Gy.


International Journal of Radiation Oncology Biology Physics | 2012

Concurrent chemoradiotherapy followed by consolidation chemotherapy with bi-weekly docetaxel and carboplatin for stage III unresectable, non-small-cell lung cancer: clinical application of a protocol used in a previous phase II study.

Jun-ichi Saitoh; Yoshihiro Saito; Tomoko Kazumoto; Shigehiro Kudo; Daisaku Yoshida; Akihiro Ichikawa; Hiroshi Sakai; Futoshi Kurimoto; Shingo Kato; Kei Shibuya

PURPOSE To assess the clinical applicability of a protocol evaluated in a previously reported phase II study of concurrent chemoradiotherapy followed by consolidation chemotherapy with bi-weekly docetaxel and carboplatin in patients with stage III, unresectable, non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS Between January 2000 and March 2006, 116 previously untreated patients with histologically proven, stage III NSCLC were treated with concurrent chemoradiotherapy. Radiation therapy was administered in 2-Gy daily fractions to a total dose of 60 Gy in combination with docetaxel, 30 mg/m(2), and carboplatin at an area under the curve value of 3 every 2 weeks during and after radiation therapy. RESULTS The median survival time for the entire group was 25.5 months. The actuarial 2-year and 5-year overall survival rates were 53% and 31%, respectively. The 3-year cause-specific survival rate was 60% in patients with stage IIIA disease, whereas it was 35% in patients with stage IIIB disease (p = 0.007). The actuarial 2-year and 5-year local control rates were 62% and 55%, respectively. Acute hematologic toxicities of Grade ≥3 severity were observed in 20.7% of patients, while radiation pneumonitis and esophagitis of Grade ≥3 severity were observed in 2.6% and 1.7% of patients, respectively. CONCLUSIONS The feasibility of the protocol used in the previous phase II study was reconfirmed in this series, and excellent treatment results were achieved.


Radiation Oncology | 2014

Can combined intracavitary/interstitial approach be an alternative to interstitial brachytherapy with the Martinez Universal Perineal Interstitial Template (MUPIT) in computed tomography-guided adaptive brachytherapy for bulky and/or irregularly shaped gynecological tumors?

Takahiro Oike; Tatsuya Ohno; Shin-ei Noda; Hiroki Kiyohara; Ken Ando; Kei Shibuya; Tomoaki Tamaki; Yosuke Takakusagi; Hiro Sato; Takashi Nakano

BackgroundInterstitial brachytherapy (ISBT) is an optional treatment for locally advanced gynecological tumours for which conventional intracavitary brachytherapy (ICBT) would result in suboptimal dose coverage. However, ISBT with Martinez Universal Perineal Interstitial Template (MUPIT), in which ~10-20 needles are usually applied, is more time-consuming and labor-intensive than ICBT alone, making it a burden on both practitioners and patients. Therefore, here we investigated the applicability of a combined intracavitary/interstitial (IC/IS) approach in image-guided adaptive brachytherapy for bulky and/or irregularly shaped gynecological tumours for which interstitial brachytherapy (ISBT) was performed.MethodsTwenty-one consecutive patients with gynecological malignancies treated with computed tomography-guided ISBT using MUPIT were analyzed as cases for this dosimetric study. For each patient, the IC/IS plan using a tandem and 1 or 2 interstitial needles, which was modeled after the combined IC/IS approach, was generated and compared with the IS plan based on the clinical ISBT plan, while the IC plan using only the tandem was applied as a simplified control. Maximal dose was prescribed to the high-risk clinical target volume (HR-CTV) while keeping the dose constraints of D2cc bladder < 7.0 Gy and D2cc rectum < 6.0 Gy. The plan with D90 HR-CTV exceeding 6.0 Gy was considered acceptable.ResultsThe average D90 HR-CTV was 77%, 118% and 140% in the IC, IC/IS and IS plans, respectively, where 6 Gy corresponds to 100%. The average of the ratio of D90 HR-CTV to D2cc rectum (gain factor (GF) rectum) in the IC, IC/IS and IS plans was 0.8, 1.3 and 1.5 respectively, while GFbladder was 0.9, 1.4 and 1.6, respectively. In the IC/IS plan, D90 HR-CTV, GFrectum and GFbladder exceeded 100%, 1.0 and 1.0, respectively, in all patients.ConclusionsThese data demonstrated that the combined IC/IS approach could be a viable alternative to ISBT for gynecological malignancies with bulky and/or irregularly shaped tumours.


Physica Medica | 2017

Fiducial marker matching versus vertebral body matching: Dosimetric impact of patient positioning in carbon ion radiotherapy for primary hepatic cancer

Satoshi Abe; Yoshiki Kubota; Kei Shibuya; Yoshinori Koyama; Takanori Abe; Tatsuya Ohno; Takashi Nakano

PURPOSE The aim of this study was to compare the dose-volume parameters of fiducial marker matching (MM) with vertebral body matching (VM) in patient positioning for carbon ion radiotherapy for primary hepatic cancer. MATERIALS AND METHODS Twenty patients with primary hepatic cancer were retrospectively studied to assess changes in reproducibility of tumor position and dose distribution on two CT scans. One was for treatment planning and another was for dose confirmation, acquired the day before the first treatment day. The coverage of the clinical target volume (CTV) (D98) and normal liver volume excluding the CTV which received 20Gy relative biological effectiveness (RBE) (V20) were used as evaluation parameters. Additionally, the correlation of tumor movement and D98 was calculated in VM and MM. The prescription dose was 60.0Gy (RBE) delivered in four fractions (15Gy/fx). RESULTS The median (range) D98 for VM and MM was 57.9 (20.8-59.9) and 59.9 (57.2-60.3) Gy (RBE), respectively. The median (range) V20 for VM and MM was 17.9 (4.8-44.4) and 16.2 (4.7-44.9) Gy (RBE), respectively. The D98 for MM was significantly larger than that for VM (p=0.001), although V20 showed no significant difference (p>0.05). Twelve patients were clinically acceptable (D98>57Gy (RBE)) with VM, while all patients were clinically acceptable with MM. Marker movement correlated with a decrease of D98 for VM (R=-0.814). CONCLUSION Compared with VM, MM was clinically acceptable in all patients. This suggests that MM is more robust than VM.


Injury-international Journal of The Care of The Injured | 2016

Prediction of extravasation in pelvic fracture using coagulation biomarkers

Makoto Aoki; Shuichi Hagiwara; Hiroyuki Tokue; Kei Shibuya; Minoru Kaneko; Masato Murata; Jun Nakajima; Yusuke Sawada; Yuta Isshiki; Yumi Ichikawa; Kiyohiro Oshima

PURPOSE To evaluate the usefulness of coagulation biomarkers, which are easy and quick to analyze in emergency settings, for prediction of arterial extravasation due to pelvic fracture. PATIENTS AND METHODS The medical records of pelvic fracture patients transferred to the emergency department of Gunma University Hospital between December 2009 and May 2015 were reviewed. Patients were divided into two groups, those with (Extra(+)) and without (Extra(-)) arterial extravasation on enhanced CT or angiography. Levels of fibrin degradation products (FDP), D-dimer, fibrinogen, the ratio of FDP to fibrinogen, the ratio of D-dimer to fibrinogen, systolic blood pressure, heart rate, the Glasgow Coma Scale, pH, base excess, hemoglobin and lactate levels, the pattern of pelvic injury, and injury severity score were measured at hospital admission, and compared between the two groups. Parameters with a significant difference between the two groups were used to construct receiver operating characteristic (ROC) curves. RESULTS The study included 29 patients with pelvic fracture. FDP, D-dimer, the ratio of FDP to fibrinogen and the ratio of D-dimer to fibrinogen were the most useful parameters for predicting arterial extravasation due to pelvic fracture. FDP, D-dimer, the ratio of FDP to fibrinogen, the ratio of D-dimer to fibrinogen, and hemoglobin and lactate levels were significantly higher in the Extra(+) group than in the Extra(-) group (FDP, 354.8μg/mL [median] versus 96.6μg/mL; D-dimer, 122.3μg/mL versus 42.1μg/mL; the ratio of FDP to fibrinogen, 3.39 versus 0.42; the ratio of D-dimer to fibrinogen, 1.14 versus 0.18; hemoglobin, 10.5g/dL versus 13.5g/dL; lactate, 3.5mmol/L versus 1.7mmol/L). The area under the ROC curves for FDP, D-dimer, the ratio of FDP to fibrinogen, the ratio of D-dimer to fibrinogen, hemoglobin and lactate levels were 0.900, 0.882, 0.918, 0.900, 0.815 and 0.765, respectively. CONCLUSION Coagulation biomarkers, and hemoglobin and lactate levels could be useful to predict the existence of arterial extravasation due to pelvic fracture. The ratio of FDP to fibrinogen and the ratio of D-dimer to fibrinogen were the most accurate markers. Coagulation biomarkers may enable more rapid and specific treatment for pelvic fracture.


PLOS ONE | 2014

Percutaneous Image-Guided Biopsy for Non-Mass-Forming Isolated Splenomegaly and Suspected Malignant Lymphoma

Hiroyuki Tokue; Satoshi Hirasawa; Hideo Morita; Yoshinori Koyma; Masaya Miyazaki; Kei Shibuya; Azusa Tokue; Sachiko Nakano; Yoshito Tsushima

Background The aim of this study was to evaluate the accuracy, safety, and role of splenic biopsy in the management of patients with non-mass-forming isolated splenomegaly and suspected malignant lymphoma. Methods Between 2001 and 2013, 137 biopsies were performed under computed tomography (CT) fluoroscopic guidance in 39 patients. All patients had splenomegaly based on the CT findings and a suspected diagnosis of malignant lymphoma based on their clinical symptoms. The spleen was the only accessible site to perform a biopsy, and no mass lesions could be identified in the spleen. Results The overall sensitivity, specificity, and diagnostic accuracy of image-guided biopsy for malignant lymphoma were 88%, 100% and 92%, respectively. Major complications occurred in 3 patients. In 1 patient, transcatheter arterial embolization was performed due to hemorrhage, and two patients needed blood transfusion because of hematoma development, without the need for further treatment. Conclusions Image-guided splenic core-needle biopsy is a safe and accurate technique with a high diagnostic accuracy in most patients who with non-mass-forming isolated splenomegaly and suspected underlying malignant lymphoma.


British Journal of Radiology | 2018

Primary postpartum hemorrhage: outcome of uterine artery embolization

Makoto Aoki; Hiroyuki Tokue; Masaya Miyazaki; Kei Shibuya; Satoshi Hirasawa; Kiyohiro Oshima

OBJECTIVE To assess the efficacy of uterine artery embolization (UAE) for the management of primary postpartum hemorrhage (PPH) and to determine the factors associated with clinical outcomes especially in relation to the ovarian artery. METHODS A retrospective analysis of 33 patients who underwent UAE for primary PPH was performed. Clinical data were used regarding maternal characteristics, cause of bleeding, mode of delivery, bleeding onset after delivery, risk factors for PPH, presence of coagulopathy, details regarding the UAE procedure, and types of ovarian artery flow. We defined two types of ovarian artery flow by initial aortography before UAE (Type A: ovarian artery flow arose directly from the aorta to the uterine artery; Type B: ovarian artery flow that did not obviously arise from the aorta). Clinical success was defined as cessation of bleeding after UAE without the need for hysterectomy. Univariate analysis was performed to determine factors related to clinical outcomes. RESULTS The major indication of UAE was uterine atony (82%; 27/33). Extravasation of contrast medium was observed in 15 (45%) patients. The clinical success rate was 85% (28/33). In five patients, embolization failed, and these patients were managed by hysterectomy. Univariate analysis showed that retained placental tissue (p < 0.001), type of ovarian artery (p < 0.001) and the existence of extravasation of contrast medium (p = 0.049) were related to the clinical success rate. CONCLUSION The clinical success rate was 85% (28/33), and some PPH patients were thought to need ovarian artery embolization in addition to UAE. Advances in knowledge: Initial aortography before UAE may be useful to predict the failure of UAE and the need of ovarian artery embolization. Obvious ovarian arterial blood flow to the uterus by aortography could be a warning sign.


Case reports in radiology | 2016

New Method of Parent Catheter Advancement in the Balloon Anchor Technique during Balloon-Occluded Transarterial Chemoembolization for Hepatic Tumors

Kei Shibuya; Hiroki Tahara; Suguru Takeuchi; Yoshinori Koyama; Yoshito Tsushima

Balloon-occluded transarterial chemoembolization (B-TACE) using a microballoon catheter is a promising method for improvement of lipiodol emulsion accumulation and local control relative to conventional transarterial chemoembolization. This method has been referred to as the balloon anchor technique in previous reports. We report a new technique for successful parent catheter advancement for achievement of stable backup for the selective insertion of a microballoon catheter during B-TACE using the microballoon as an anchor, even in patients with tortuous anatomy of the hepatic and celiac arteries. Deep cannulation of parent catheters was accomplished in all three cases and complications such as vascular injury were not observed in the postprocedure angiograms.


CardioVascular and Interventional Radiology | 2016

Percutaneous Direct Puncture Embolization with N -butyl-cyanoacrylate for High-flow Priapism

Hiroyuki Tokue; Kei Shibuya; Hiroyuki Ueno; Azusa Tokue; Yoshito Tsushima

There are many treatment options in high-flow priapism. Those mentioned most often are watchful waiting, Doppler-guided compression, endovascular highly selective embolization, and surgery. We present a case of high-flow priapism in a 57-year-old man treated by percutaneous direct puncture embolization of a post-traumatic left cavernosal arteriovenous fistula using N-butyl-cyanoacrylate. Erectile function was preserved during a 12-month follow-up. No patients with percutaneous direct puncture embolization for high-flow priapism have been reported previously. Percutaneous direct puncture embolization is a potentially useful and safe method for management of high-flow priapism.

Collaboration


Dive into the Kei Shibuya's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Masaru Wakatsuki

National Institute of Radiological Sciences

View shared research outputs
Researchain Logo
Decentralizing Knowledge