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Biomedical subjects

E Hagami

Publications and source records attributed to E Hagami.

12 recordsLinked to original sources
PubMed1989

[Requirement for radiation shields of transportation pipe for on line inhalation gases from compact cyclotron in positron emission tomography].

In the unit housing of a compact cyclotron and positron emission CT (PET), positron emitting gas such as 15O, 11C, C15O2, C15O etc. is supplied from a cyclotron to a PET room through a transportation pipe with an appropriate shield to reduce positron annihilation radiation. Using lead or concrete shield blocks with various thicknesses, radiation leakage through the shield was measured by an ionization chamber type survey meter during continuous and constant supply of 15O gas of 1.85 GBq/min concentration which is the maximum dose for clinical use. The leakage radiation measured was 213.7, 56.0, 15.3, 5.0 muSv/week for lead shield with 1, 2, 3, and 4 cm thickness, respectively, and 193.3, 30.5 and 5.1 muSv/week for concrete shields with thickness of 10, 20, and 30 cm, respectively. The present study shows that to keep less than 300 muSv/week, which is the permissible dose rate of the boundary zone around the radiation controlled area by Japan Science and Technology Agency, it is required to use more than 8 mm thick lead shield or 7 cm thick concrete for continuous supply of 1.85 GBq/min 15O gas.

Carbon Dioxide↗
PubMed1981

[Measurement of regional cerebral blood flow by 133Xe inhalation method -experimental system and its evaluation of data analysis by simulation study (author's transl)].

Noninvasive measurement of regional cerebral blood flow (rCBF) by 133Xe inhalation and simulation studies of the errors in analyzing 133Xe clearance curves were reported. Our system was based on Obrist's 10 minutes desaturation method after 1 minute inhalation of 185 approximately 222 MBq (5 approximately 6 mCi)/l of 133Xe gas mixed in the air. Clearance curves were simultaneously measured at six location in each hemisphere. End-tidal 133Xe curve used for correction of recirculation was generated from respired air curve. Values for rCBF were calculated by two compartment analysis of the head curves. We evaluated the experimental errors with computer simulation studies. The synthetic head curves were generated with a three compartmental model representing the fast and slow component in the brain and the extracerebral component. The arterial input function used was the end-tidal curves of a typical control subject. The results of computer simulation studies were obtained as follows: F1 that is the flow of the fast compartment in brain and adequate reliability; statistical errors for normal value of F1 (80 ml/100 g/min) were 5% at 30 kcpm; the optimum end point of curve-fitting was 10 approximately 11 minutes after 1 minute inhalation of 133Xe gas; the error due to remaining activities of repreceding study was 3% at the interval of 25 minutes between inhalation.

Cerebrovascular Circulation↗