Venti-Scan III Particle Size Test

Robert J. Perry. B.Sc.
Department of Medicine
Pulmonary Disease Division
SUNY Stony Brook
HSC T-17 Rm. 040
Stony Brook, NY 11794-8172

Jonathan S. Howite. MD.
Winthrop University Hospital
Pulmonary & Critical Care Medicine
Director, Pulmonary Rehabilitation
Medical Director, Respiratory Therapy
222 Station Plaza North Suite 400
Mincola, NY 11501

The following report summarizes our analysis of the Biodex Venti-Scan III (#177-080) disposable radioaerosol system for ventilation scanning studies. Using Andersen cascade impactor we determined the mean particle size of the technetium 99m-DTPA aerosol produced by six units from lot#014504 under the following testing parameters.

Nebulizer solution: 2cc's Tc-99m DTPA
Nebulizer Flow: 10liters/min @50 psi
System ventilation: 15bpm via Harvard pump @ 600 cc's

All six systems produced essentially the same size Tc-99m DTPA aerosol as illustrated in the average graph of aerosol diameter vs. cumulative percent.

Mean MMAD: 0.50 microns +/- 0.01 (S.D.)
Range: 0.48-0.52
Mean GSD: 1.8 (poly dispersed)

This highly reproducible aerosol particle size is desirable for the deep lung penetration required in nuclear medicine lung ventilation studies.

In addition, one system was tested for filter efficiency in trapping the Tc-99m DTPA aerosol. With the T-piece plugged, the aerosol was run through the HEPA filter followed by an absolute filter for a total of 5 min. There was no Tc-99m activity detected on the absolute filter indicating a HEPA filter efficiency of 100% in the one unit tested. It is not known however if this preliminary result can be extrapolated to represent a group of this type of filter without further confirmation in a formal study. Depending on the quality control during production of these filters it seems likely that they are very efficient.