Modeling Deposition of Inhaled Particles - Aerosols: Measurement, Dosimetry, and Health Effects - page 108

Zone P

Zone P

Zone I

Zone I

Zone C

Zone C

10,000,000

1,000,000

100,000

10,000

1,000

Zone C
Zone I
Zone P

100

10

1

0

1 3 5 7 9 11 13 15 17 19 21 23

(A) (B) (C) Airway generation

FIGURE 5.10 Association of the central, intermediate, and peripheral zones (A) of planar gamma camera
images with a corresponding computerized lung branching network model (B). Panel (C) shows the resulting
distribution of lung airways within each zone.

Individual voxel

Airway composition

Width of SPECT slice

FIGURE 5.11 SPECT image of radiolabeled aerosol distribution in the human lung and an associated voxel
of the branching computer model; the composition of airways within the voxel is shown.

associated with inhaled particles, it is desirable to obtain deposition measurements at ever-iner levels
of spatial resolution, measuring the dose to individual airway structures or cells. Unfortunately, there
is little such data available. Schlesinger et al. 258 performed local deposition studies of 8 μm particles
in a cast of an airway bifurcation. After the aerosols were deposited, the airway cast (Figure 5.12)
was cut open and a microscope was used to count the number of particles in 1 mm square regions