Biomedical subjects

Kouji Yokoyama

Publications and source records attributed to Kouji Yokoyama.

5 recordsLinked to original sources

PubMed2005

[Experience in IVR performed using a posture support device designed especially for a patient unable to take the decubitus position].

We were requested to perform IVR for uterine artery embolotherapy of a patient who was unable to take the decubitus position. Because of extreme overweight, the patient was limited to a sitting posture on a bed in the living environment. Therefore, a device to support her sitting posture on the IVR patient table was designed and created. The support device was used to hold the patient's body in a half-sitting posture and distribute her weight load appropriately so that the weight load applied to the patient's body could be minimized. Using this support device, IVR could be performed smoothly during a period of 2 hours 40 minutes.

Arteries↗

PubMed2004

[Clinical study with angiography system using a flat panel detecter].

We have been using an X-ray angiography system that incorporates a flat panel detector (FPD) since December 2001. This system is equipped with the scintillator-type FPD PaxScan 4030A from Varian Medical Systems, and for objective comparison of the image intensifier (I.I.) and FPD, the system is constructed so that these detectors can be used alternatively. Using this system and other X-ray angiography systems, visual studies have been conducted on the digital subtraction angiography (DSA) images acquired by FPD and I.I. We have found from the clinical images that the FPD is superior to the I.I. in depiction of fine blood vessels as well as of physical characteristics. Fluoroscopy images acquired by the FPD were not entirely satisfactory, however the improvement made in its performance now permits equal use of the FPD and I.I. systems.

Angiography, Digital Subtraction↗

PubMed2004

[Newly developed monitor for IVR: liquid crystal display (LCD) replaced with cathode ray tube (CRT)].

For physicians who monitor images during interventional radiology (VR), we have built and been using a system that employs a liquid crystal display (LCD) instead of the conventional cathode ray tube (CRT). The system incorporates a ceiling-suspension-type monitor (three-display monitor) with an LCD on each of the three displays for the head and abdominal regions and another ceiling-suspension-type monitor (5-display monitor) with an LCD on each display for the cardiac region. As these monitors are made to be thin and light in weight, they can be placed in a high position in the room, thereby saving space and allowing for more effective use of space in the X-ray room. The system has also improved the efficiency of operators in the IVR room. The three-display folding mechanism allows the displays to be viewed from multiple directions, thereby improving the environment so that the performance of IVR can be observed.

Data Display↗

PubMed2002

Radiation-chemical properties of the hypoxic cell radiosensitizer doranidazole (PR-350).

This study was performed to confirm the radiation-chemical properties of the 2-nitroimidazole derivative doranidazole, (+/-)-(2RS,3SR)-3-[(2-nitroimdazol-1-yl)-methoxy]butane-1,2,4-triol [CAS 137339-64-1], PR-350, which was synthesized as a hypoxic cell radiosensitizer with low toxicity. Radiation-chemical experiments using doranidazole showed that (1) unlike O2, it had high reactivity toward not only hydrated electrons (eaq-), but also hydroxyl radicals (.OH), (2) the reduced intermediates of doranidasole had no ability to induce immediate strand breaks of colE1 plasmid DNA, (3) doranidazole enhanced radiation-induced DNA strand breaks of colE1 plasmid DNA in the aqueous state, whereas it did not enhance the base alteration, such as 8-oxo-deoxyguanosine, (4) it enhanced the radiation-induced formation of strand breaks with 3'-phosophate and 3'-phosphoglycolate termini, and (5) it was bound to DNA after irradiation. These facts revealed that the majority of radiation-chemical properties of doranidazole, except for the high reactivity toward OH, were similar to those of oxygen.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2002

[An experience of the clinical study with angiography system using a Flat Panel Detector].

We had the chance of clinical studies by new proto-type Digital Subtraction Angiography (DSA) System with the Flat Panel Detector (FPD). That system has two types of detector, FPD and I.I.-CCD camera, and we can compare with image quality in clinical. We measured and discussed about the physical characteristic data of both detectors. Up to physical characteristic evaluation, FPD has good MTF and SNR performance, comparing with I.I.-CCD camera. In clinical evaluation, DSA image of FPD was superior to that of I.I.-CCD camera by visual comparison of medical doctors. Finally we discussed about the feasibility of replacement of detectors. We expect that DSA system will accept FPD in near future.

Angiography, Digital Subtraction↗