Biomedical subjects

Kazutaka Masuda

Publications and source records attributed to Kazutaka Masuda.

3 recordsLinked to original sources

PubMed2006

[Examination of attenuation correction using low-dose computed tomography].

Attenuation correction is necessary for the reconstruction of SPECT images. One report has mentioned that attenuation correction by X-ray computed tomography (CT) is effective for a non-uniform attenuation body. We examined the effect of attenuation correction on SPECT images by changing the scanning conditions of CT, and evaluated the possibility of attenuation correction by low-dose CT. The phantom was scanned under several X-ray tube conditions varying from 80 kV to 135 kV and from 7.5 mAs to 200 mAs. We obtained equations of attenuation correction based on the Hounsfield Unit (HU) units of each pixel and compared the effects of attenuation correction. The results showed that the equation for attenuation correction under each condition did not vary significantly, and the effects of attenuation correction by the equations did not vary significantly between CT of low dose and that of clinical dose. This result suggest that the attenuation correction obtained by low-dose CT was equal to that obtained by the clinical dose. In conclusion, it seemed that the equation and map of attenuation correction matched with each radionuclide yielded more adequate attenuation correction than conventional methods.

Image Processing, Computer-Assisted↗

PubMed2004

[Investigation of radioactivity measurement of medical radioactive waste].

To explore the possibility of which medical radioactive wastes could be disposed as general wastes after keeping them a certain period of time and confirming that their radioactivity reach a background level (BGL), we made a survey of these wastes in several nuclear medicine facilities. The radioactive wastes were collected for one week, packed in a box according to its half-life, and measured its radioactivity by scintillation survey meter with time. Some wastes could reach a BGL within 10 times of half-life, but 19% of the short half-life group (group 1) including 99mTc and 123I, and 8% of the middle half-life group (group 2) including 67Ga, (111)In, and 201Tl did not reach a BGL within 20 times of half-life. A reason for delaying the time of reaching a BGL might be partially attributed to high initial radiation dose rate or heavy package weight. However, mixing with the nuclides of longer half-life was estimated to be the biggest factor affecting this result. When disposing medical radioactive wastes as general wastes, it is necessary to avoid mixing with radionuclide of longer half-life and confirm that it reaches a BGL by actual measurement.

Half-Life↗

PubMed2003

[Introduction of manual for the management radioactive medical waste].

Societies concerned with radioactive rays and nuclear medicine have recently highlighted the necessity of managing radioactive medical waste resulting from nuclear medicine examinations. We introduce a manual that we have created and explain its use in decision-making and management practices aimed at the reduction of radioactive medical waste at hospitals that have not yet solved this problem. We hope that our manual will help in reducing this medical waste.

Japan↗