Radioaerosol deposition

A means for estimating accurately hourly radioaerosol deposition on the basis of easily obtained meteorological parameters is highly desirable. However, such relationships have not yet been satisfactorily developed. For the purpose of the HTM-1, hourly fallout estimates have been made during rainfall periods, using the assumption that... 

Eberl S, Chan HK, Daviskas E. SPECT imaging for radioaerosol deposition and clearance studies. J Aerosol Med Deposition Clear Eff Lung 2006 19 8-20. 

Newman and colleagues (69) studied the radioaerosol deposition and bron-chodilator response to 100 pg salbutamol administered from a conventional MDI and from the Autohaler in 18 asthmatic patients. In the 10 patients who could coordinate acmation and inhalation of their own MDIs, deposition of aerosol in the lungs and bronchodilator response were equivalent. In contrast, for the 8 patients... 

The radioactivity ratio of potentially unfractionated fission product radionuclides in precipitation should be independent of the amounts of aerosol and water vapor removed from the air masses. For an air mass containing uniformly mixed radioaerosols from the same nuclear explosion, the ratios should be the same by time and collection-site latitude along the coast. The ratios at storm date may be calculated for depositions following a specifically known atmospheric nuclear explosion with known initial production quantities. The presence of longer lived radio-... 

A second factor in the deposition process is the physical size of the radioaerosol particles deposited during dry deposition. Particle size affects the efficiency of foliar collection of dry aerosol particles and may also be important in determining the rate of solution of soluble constituents within the aerosol particle. Lockhart et al. (7) indicated that nuclear debris in surface level air is generally associated with aerosol particle sizes about 0.5-1.0p in diameter. Martell (8) stated that high yield detonations causing condensation of "Sr at stratospheric altitudes leads to the formation of particles with diameters less than 1 fi. Hence,... 

When designing protocols to measure deposition, a number of clinical factors need to be considered and incorporated into the study design subjects age, sex, smoking history, and current drug regimens, presence of a viral infection, severity of disease, stability of pulmonary function, and other outcome measures that could affect the inhalation of the radioaerosol, the measurement of deposition, and the results. Some of these also apply when using healthy volunteers as subjects for deposition studies. For example, we allow a 4- to 6-week recovery period between repeat studies for subjects who have suffered an exacerbation of their asthma or developed a chest cold or infection after enrollment. 

MCC is measured by imaging the lung over time to obtain the retention of an inhaled radioaerosol. Planar imaging is used mainly, and serial measurements are required. Because aerosol size and ventilatory parameters affect where aerosol is initially deposited in the lung and because the rate of transport is more rapid from proximal airways than peripheral airways, changes to the initial deposition pattern as a result of treatment or the factors listed in Table 3 will... 

Bondesson E, Asking L, Borgstrom L, et al. In vitro and in vivo aspects of quantifying intrapulmonary deposition of a dry powder radioaerosol, hit J Pharm 2002 232 149-156. 

Lin MS, Goodwin DA. Pulmonary deposition of an inhaled radioaerosol on obstructive pulmonary disease. Radiology 1976 118 645-651. 

Clay and Clarke (209) compared administration of technetium in 0.9% saline using three different nebulizers, one with a particle size of 1.8, the other with one of 4.6, and the third with 10.3 pm. Lung deposition were 79, 59, and 44%, of the aerosol released from the nebulizer and deposited in the body, respectively. Methodological errors might have been introduced in that the radioaerosol released from the nebulizer was determined using weight measurements before and after inhalation. 

---