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Dive into the research topics where Keiichiro Nishimura is active.

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Featured researches published by Keiichiro Nishimura.


Radiation Medicine | 2008

Evaluation of quality of life and psychological response in cancer patients treated with radiotherapy

Takeo Takahashi; Mikito Hondo; Keiichiro Nishimura; Akira Kitani; Takafumi Yamano; Hisami Yanagita; Hisato Osada; Munefumi Shinbo; Norinari Honda

PurposeThe importance of the quality of life (QOL) and mental condition of patients being treated for cancer is now recognized. In this study, we evaluated QOL and mental condition in patients with cancer before and after radiotherapy.Materials and methodsThe subjects were 170 patients who had undergone radiotherapy. The examination of QOL was performed using the quality of life questionnaire for cancer patients treated with anticancer drugs (QOL-ACD), and mental condition (anxiety and depression) was examined using the hospital anxiety and depression scale (HADS). These examinations were performed at the start of radiotherapy and immediately after radiotherapy.ResultsThe QOL score was slightly higher in all patients after the completion of radiotherapy than before the start of radiotherapy. In the palliative radiotherapy group, QOL score was significantly improved by treatment. Anxiety and depression were improved after radiotherapy. There was a correlation between the degrees of improvement of the HADS and QOL score.ConclusionWe could treat cancer patients by radiotherapy without reducing their QOL, and improvement in QOL was significant in the palliative radiotherapy group. Mental condition was also improved after radiotherapy.


Radiology | 2012

Imaging of Ventilation with Dual-Energy CT during Breath Hold after Single Vital-Capacity Inspiration of Stable Xenon

Norinari Honda; Hisato Osada; Wataru Watanabe; Mitsuo Nakayama; Keiichiro Nishimura; Bernhard Krauss; Katharina Otani

PURPOSE To assess single-breath-hold technique for ventilation mapping by using dual-energy computed tomography (CT) in phantom experiments and volunteers. MATERIALS AND METHODS Institutional review board approved this study, and written informed consent was obtained from all volunteers. A rubber bag filled with a mixture of xenon (0%-35.4%) and oxygen was scanned with dual-source dual-energy CT (80 kV and 140 kV with tin [Sn] filter [Sn/140 kV] and 100 kV and Sn/140 kV). A cylinder containing six tubes of identical sizes with different apertures was ventilated once with a mixture of 35% xenon and 65% oxygen and was scanned in dual-energy mode (80 kV and Sn/140 kV). Xenon-enhanced images were derived by using three-material decomposition technique. Four volunteers were scanned twice in dual-energy mode (80 kV and Sn/140 kV) during breath hold after a single vital-capacity inspiration of air (nonenhanced) and of 35% xenon. Xenon-enhanced images were obtained by using two methods: three-material decomposition and subtraction of nonenhanced from xenon-enhanced images. Regression analysis with t and F tests was applied to the data of the rubber bag scans, with the significance level set at .05. RESULTS Mean pixel values of gas in the bag were linearly related to xenon concentration for all x-ray tube voltages (r(2) = 1.00, P < .00001). Pixel values of the xenon-enhanced images of the tubes were related to their aperture size. Nearly homogeneous (coefficient of variation: 0.22, 0.23, and 0.34) pixel values were found in the lungs of healthy volunteers, with higher pixel values in the trachea and lower pixel values in the bullae. Xenon-enhanced images calculated by using three-material decomposition had better image quality on visual comparison than those calculated by using subtraction. CONCLUSION Xenon-enhanced dual-energy CT with the single-breath-hold technique could depict ventilation in phantoms and in four volunteers.


Annals of Nuclear Medicine | 2002

Quantitative lung perfusion scintigraphy and detection of intrapulmonary shunt in liver cirrhosis

Makoto Hosono; Kikuo Machida; Norinari Honda; Takeo Takahashi; Akio Kashimada; Hisato Osada; Osamu Murata; Nobuyuki Ohtawa; Keiichiro Nishimura

Objective: Frequent association between liver cirrhosis and hypoxemia has been well documented. It is mostly attributable to intrapulmonary shunt due to dilation of pulmonary vasculature. We performed quantitative lung perfusion scintigraphy to detect an intrapulmonary shunt in cirrhosis patients.Methods: Prior to injection, Tc-99m MAA was applied to thin layer chromatography for quality control. Three cirrhosis patients who had hypoxemia were examined as well as 11 control subjects. After i.v. injection of Tc-99m MAA, whole body anterior and posterior images were taken at 5 min in patients with cirrhosis and at 8 time points up to 60 min in control subjects. Regions of interest were placed at the bilateral lungs and the whole body, and pulmonary accumulation was calculated.Results: All the control subjects demonstrated more than 90% of radioactivity in the lungs until 20 min. In contrast, all the patients showed values less than 80% at 5 min. In the cirrhosis patients with hypoxemia, the presence of intrapulmonary shunt was confirmed on quantitative lung perfusion scan. In control subjects, pulmonary accumulation of Tc-99m MAA dropped as a function of time and became less than 90% after 30 min.Conclusion: The timing, of measurements is essential in evaluating intrapulmonary shunt.


Annals of Nuclear Medicine | 2004

Extraosseous accumulation of99mTc-MDP in lymph node metastases of small cell carcinoma of the esophagus

Takeo Takahashi; Kikuo Machida; Norinari Honda; Makoto Hosono; Shinya Oku; Hisato Osada; Osamu Murata; Keiichiro Nishimura; Hitoshi Ohno

We report a case of esophageal carcinoma that showed extraosseous accumulation of99mTc-MDP in lymph node metastases to the cervical and paracardial lymph nodes. There are few cases showing abnormal extraosseous accumulation of99mTc-MDP in esophageal cancer lesion. The patient was a 53-year-old man with advanced esophageal cancer. Bone scintigraphy demonstrated extraosseous accumulations in left supraclavicular and paracardial lymph node metastases. The histopathological diagnosis was small cell carcinoma of the esophagus, which is a rare disease with aggressive behavior and poor prognosis. Our patient underwent 2 courses of systemic chemotherapy (CDDP + VP16), but died of rapidly growing systemic metastases 5 months after the initial treatment.


Radiation Medicine | 2008

Multidetector computed tomography diagnosis of primary and secondary epiploic appendagitis

Hisato Osada; Hitoshi Ohno; Wataru Watanabe; Kei Nakada; Takemichi Okada; Hisami Yanagita; Keiichiro Nishimura; Mikito Hondo; Takeo Takahashi; Norinari Honda

PurposeThe aim of this study was to evaluate the epiploic appendages in patients with acute abdomen using multidetector computed tomography (MDCT) and to determine the incidence of primary and secondary epiploic appendagitis (EA).Materials and methodsA radiologist reviewed MDCT images from 1338 patients with acute abdomen for visible epiploic appendages. Two radiologists then reviewed the MDCT images showing inflamed epiploic appendages and diagnosed primary EA, secondary EA, or other conditions by consensus. The CT criteria for primary EA are a round or oval pericolonic fatty lesion with a hyperattenuated rim and adjacent fat stranding, without other causes of inflammation. Secondary EA is diagnosed if an epiploic appendage is found to be due to inflammation from other inflammatory entities.ResultsEpiploic appendages were identified in 19 patients. Four patients (0.3%) had a retrospective CT diagnosis of primary EA. Twelve patients (0.9%) had a retrospective CT diagnosis of secondary EA (primary condition was diverticulitis in 10 patients and inflammatory bowel disease in 2 patients). The remaining three patients had calcification of an epiploic appendage suggestive of old EA.ConclusionPrimary EA should be included in the differential diagnosis of acute abdomen. Occasionally, inflammation of the epiploic appendages is secondary to other inflammatory conditions.


Journal of Palliative Care & Medicine | 2014

Role of Palliative Radiotherapy for Bone Metastasis

Takeo Takahashi; Keiichiro Nishimura; Takafumi Yamano; Masatoshi Gika

With approximately 50-70% of patients with advanced cancer developing bone metastases during the course of their disease, treatment of bone metastases depends on many factors including performance status, pathology, site of disease, and neurologic status [1]. Radiotherapy has become highly precise, improving local control and facilitating minimally invasive treatment, and has attracted attention as a curative treatment method comparable to surgery. On the other hand, radiotherapy also plays an extremely important role in palliative treatment for advanced cancer patients [2]. Palliative care and treatment is aimed at providing relief from pain and other symptoms. Curative and palliative radiotherapies differ in the radiation field size, dose fraction, and treatment schedule. We review the role of radiotherapy in palliative treatment for patients with symptomatic bone metastases.


Journal of Radiation Research | 2013

Usefulness of double dose contrast-enhanced magnetic resonance imaging for clear delineation of gross tumor volume in stereotactic radiotherapy treatment planning of metastatic brain tumors: a dose comparison study

Kalloo Sharma Subedi; Takeo Takahashi; Takafumi Yamano; Jun-ichi Saitoh; Keiichiro Nishimura; Yoshiyuki Suzuki; Tatsuya Ohno; Takashi Nakano

The purpose of this study was to compare the size and clearness of gross tumor volumes (GTVs) of metastatic brain tumors on T1-weighted magnetic resonance images between a single dose contrast administration protocol and a double dose contrast administration protocol to determine the optimum dose of contrast-enhancement for clear delineation of GTV in stereotactic radiotherapy (SRT). A total of 28 small metastatic brain tumors were evaluated in 13 patients by intra-individual comparison of GTV measurements using single dose and double dose contrast-enhanced thin-slice (1-mm) magnetic resonance imaging (MRI). All patients had confirmed histological types of primary tumors and had undergone hypo-fractionated SRT for metastatic brain tumors. The mean tumor diameter with single dose and double dose contrast-enhancement was 12.0 ± 1.1 mm and 13.2 ± 1.1 mm respectively (P < 0.001). The mean incremental ratio (MIR) obtained by comparing mean tumor diameters was 11.2 ± 0.02 %. The mean volume of GTV-1 (single dose contrast-enhancement) and GTV-2 (double dose contrast-enhancement) was 1.38 ± 0.41 ml and 1.59 ± 0.45 ml respectively (P < 0.01). The MIR by comparing mean tumor volumes was 32.3 ± 0.4 %. The MIR of GTV-1 with < 1ml volume and GTV-1 with > 1ml volume was 41.8 ± 0.05 % and 12.4 ± 0.03 % respectively (P < 0.001). We conclude that double dose contrast-enhanced thin-slice MRI is a more useful technique than single dose contrast-enhanced thin-slice MRI, especially for clear delineation of GTVs of small metastatic brain tumors in treatment planning of highly precise SRT.


Journal of Gastrointestinal and Digestive System | 2013

Role and Progression of Radiotherapy for Locally Advanced Esophageal Cancer

Takeo Takahashi; Keiichiro Nishimura; Takafumi Yamano

Radiotherapy plays an important role in the treatment of locally advanced esophageal cancer. And, definitive chemoradiotherapy is widely accepted treatment methods for advanced esophageal cancer. Radiation dose-escalation has failed to improve local control or survivals. However, irradiation techniques have been advancing markedly. 3-dimensional radiotherapy, intensity modulated radiotherapy (IMRT), and particle beam therapy is a highly precise radiotherapy in which the dose distribution can be fitted according to the shape of tumor. Future Directions will evaluate the dose-escalation using highly precise radiotherapy and adequate radiation field for locally advanced radiotherapy.


Radiation Medicine | 2007

Arteriovenous malformation of the gallbladder: CT and angiographic findings

Hisato Osada; Norinari Honda; Takeo Takahashi; Shinya Oku; Wataru Watanabe; Takemichi Okada; Hitoshi Ohno; Mikito Hondo; Keiichiro Nishimura

We encountered a case of arteriovenous malformation (AVM) of the gallbladder in a patient with hepatocellular carcinoma (HCC). Contrast-enhanced computed tomography (CT) showed serpentine vessels around and within the gallbladder wall. Angiography showed dilated and tortuous cystic arteries, a racemose vascular network, and early-filling cystic veins. Transcatheter arterial embolization of two cystic arteries feeding the AVM was performed with platinum microcoils prior to transcatheter arterial chemoembolization for HCC to prevent embolic particles from flowing into these arteries. Follow-up contrast-enhanced CT showed blood flow in the gallbladder AVM, which appeared to be fed by the arterial collaterals.


Australasian Physical & Engineering Sciences in Medicine | 2018

Retrospective analysis of multi-institutional, patient-specific treatment planning results of high-dose-rate intracavitary brachytherapy for gynecological cancer using V100%

Tetsuya Watanabe; Hisayuki Miyashita; Ryoichi Notake; Keisuke Todoroki; Go Nakajima; Kana Washizu; Nobuko Utsumi; Shogo Hatanaka; Masatsugu Hariu; Takafumi Yamano; Keiichiro Nishimura; Munefumi Shimbo; Takeo Takahashi

The objective of this study was to clarify the usefuleness of the K parameters of the independent verification method using V100% (the volume of water receiving 100% of the prescription dose) for institutions implementing the high-dose-rate (HDR) intracavitary brachytherapy for gynecological cancer. The data of 249 plans of 11 institutions in Japan were used, and the constant K value obtained by a parameter fit for single-192Ir, two-192Ir, and three-192Ir systems was calculated. The predicted total dwell time calculated using the constant K value was defined as Tpr, and the total dwell time calculated using a radiation treatment planning system was defined as TRTP. The ratio of Tpr and TRTP for each plan was calculated. The constant K values (95% CI) obtained for each system outlined above were 1233 (1227–1240), 1205 (1199–1211), and 1171 (1167–1175), respectively. Regarding the Tpr/TRTP, the entire data were within 0.9–1.1. For accurate verification, it was clarified that constant K values should be calculated for each system. The Nuclear Regulatory Commission considers a difference of 20% between the prescribed total dose and the administered total dose as a reportable medical event. There is a need for a quick method to verify the accuracy with a minimum of 10% threshold of a plan. The constant K values in this study were obtained from multiple institutions, and the variation in the values among these institutions was small. The data obtained by this study may be used as a parameter of this verification method employed by numerous institutions, particularly those who have recently initiated HDR brachytherapy. In addition, for institutions already using this method, this data might be useful for the validation of the parameters which were used in such institutions.

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Takeo Takahashi

Saitama Medical University

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Hisato Osada

Saitama Medical University

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Norinari Honda

Saitama Medical University

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Mikito Hondo

Saitama Medical University

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Takafumi Yamano

Saitama Medical University

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Wataru Watanabe

Saitama Medical University

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Hitoshi Ohno

Saitama Medical University

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Kana Washizu

Saitama Medical University

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Munefumi Shimbo

Saitama Medical University

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