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Toshihiro Ogura

Publications and source records attributed to Toshihiro Ogura.

6 recordsLinked to original sources
PubMed2005

[Evaluation of Intra-abdominal fat distribution using X-ray CT data for detection of rectal cancer].

To develop a novel method of detecting rectal cancer, we assessed relationships between intra-abdominal fat distribution and rectal cancer in Japanese patients. Subjects comprised 38 patients with rectal cancer apparent on CT-colonography and 110 other cases. The intra-abdominal fat area was determined by calculating pixel distribution with attenuation values from -140 HU to -40 HU. The area of intra-abdominal fat was measured on axial images using an interslice gap of 10 mm. Profile curves of intra-abdominal fat were in the plane direction from diaphragm to anus. Of note is the fact that Ogura's peak, a secondary small peak around the rectal cancer, was apparent on the profile of intra-abdominal fat, with 73.7% of rectal cancers displaying Ogura's peak. In comparison, only 19.1% of other cases displayed Ogura's peak on this profile. The relationship between fat and rectal cancer is difficult to explain. However, making good use of these results showing intra-abdominal fat distribution, a computer-aided diagnosis (CAD) system for detecting rectal cancer according to the presence of Ogura's peak has potential as a method of mass screening. As only 148 cases were investigated in the present study, the accumulation of additional data is needed. More detailed studies with larger patient populations are warranted.

Abdominal Cavity↗
PubMed2005

[New method of estimating effective energy for X-ray CT scanners].

Because the exposure dose in X-ray computed tomography examinations is sometimes difficult to determine, it is important to be able to estimate the dose for these examinations. The effective energy of the X-ray CT scanner is required to estimate exposure dose. Although the half-value-layer (HVL) method has been used to calculate effective energy, it is not an easy method. This paper proposes a technique by which effective energy can be easily calculated. Certain details were found to cause change in effective energy, and the ratio (inner-metal center-air ratio: IMCAR) between air dose and dose in fixing the metallic pipe in the isocenter of an X-ray CT scanner was necessary. The IMCAR from a different X-ray CT scanner was required, and, when effective energy was calculated, it showed an error of less than 0.7% for the half-value-layer method. The effect of this error on dose estimation was slight (0.4%). This technique is useful, because effective energy can easily be calculated with a high degree of accuracy.

Radiation Dosage↗
PubMed2004

Improved dissolution of an insoluble drug using a 4-fluid nozzle spray-drying technique.

A solid dispersion of the drug can be made using a polymer carrier to improve solubility. Generally, drugs become amorphized when solid dispersion is formed using a polymer carrier. In such high energy conditions, the solubility of the drug molecule is increased. We previously prepared solid dispersion using a spray-drying technique and reported its solubility and crystallinity. In this study, hydroxypropylmethylcellulose (HPMC) was used as the carrier, and tolubutamide was the model drug, which is water-insoluble. Solubility was evaluated by preparing a solid dispersion using a newly developed 4-fluid nozzle spray dryer. Observation of particle morphology by scanning electron microscopy (SEM) revealed that the particles from the spray drying were atomized to several microns, and they had also become spherical. Assessment of the crystallinity of the spray-dried particles by powder X-ray diffraction and differential scanning calorimetry demonstrated that the tolbutamide had been amorphized, forming a solid dispersion. The apparent release rate constant K of the drug from the spray-dried particles was 4 to 6 times faster than the original drug in pH 1.2, and it was also 1.5 to 1.9 times faster than the original drug in pH 6.8. The 70% release time (T(70)) of the drug from the spray-dried particles was 20 to 30 times faster than the original drug in pH 1.2 solution as well as 2 to 3 times faster than the original drug in pH 6.8 solution. Pharmaceutical preparations prepared in this way using the 4-fluid nozzle system spray dryer formed composite particles, resulting in a remarkably improved dissolution rates of the drug.

Crystallization↗
PubMed2004

[Comparative evaluation of absorbed dose and image quality in X-ray head CT scanning for hospital facilities in Gunma.].

Recently, the number of scans for X-ray computed tomography (CT) examinations has been rising due to the wide-spread use of multi-slice CT (MSCT) scanners. There is a concern that the total medical exposures will be increased by these examinations. In order to lower exposures, routine parameters for head CT examinations done at several hospitals in Gunma were investigated. In this study, the computed tomography dose index (CTDI(100, C)), noise, and low contrast resolution were measured. The CTDI(100, C) for all the hospitals exceeded the guideline (40mGy) suggested by the Japan Association of Radiological Technologists (JART). Low contrast resolution showed the coefficient of variation of +/-5% between hospitals. In conclusion, it was proposed that the technologists should reconsider the parameters of the head X-ray CTs, in cases where their output dose far exceeds the standard.

Head↗