Abstract
Using133Xe, a xenon lung function unit (Model 36-001, Nuclear Associates, INC.) and a large area scintillation camera (the effective field, 34 cm in diameter), combined with computer analysing technique (TOSBAC C3400 Model 31), the regional pulmonary function was evaluated.
Regional clearance half time (T1/2), time constant (τ) and ratios of disappearance constant (λi/λt) were calculated from wash out curves for equilibrated gas in the steady state.
These dynamic indices were compared with regional ventilation indices (Vi) and perfusion indices (Qi) obtained by a single breath method.
In a steady state method, the late part of133Xe wash out curves was affected by radioactivity in chest wall, mediastinum and great vessels.
We compared wash out curves of equilibrated gas during normal breathing with those during hyperventilation and those of perfused gas during normal breathing.
These data indicated that the late part (after 4 minutes) of wash out curves was dependent on radioactivity in tissue without air space.
For calculating the accurate values of dynamic ventilation, correction was made for the errors by the computer.
In our method using 5-10 mCi133Xe, each values in lung field, arbitrary divided into 24 zones, can be measured with time interval for 8 seconds.
Dynamic indices as well as static indices in 7 healthy subjects tended to increase from upper to lower zone.
The differences in each zones and standard errors of the data by the steady state method were smaller than those by the single breath method.
