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Corrections in dose assessment of 99mTc radiolabeled aerosol particles targeted to central human airways using planar gamma camera imaging.
J. Aerosol Med. Pulm. Drug Deliv. 22, 45-54 (2009)
The dose of inhaled radiolabeled aerosols is usually assessed using gamma (GC) camera imaging. Because of the complex and inhomogeneous structure of the lung, consisting of soft tissue, the thoracic skeleton, blood vessels, and air spaces, proper attenuation correction coefficients are difficult to evaluate and the estimated doses bear high uncertainty. One hundred milliliters of aerosol boli composed of 100 nm diameter Tc-99m radiolabeled carbon particles (Technegas) were targeted either to the airways (AW) or to 800-mL volumetric lung depth (alveoli, AL) in 11 healthy volunteers. In addition, 750-mL full breaths (FB) of aerosol were inhaled to a 800-mL lung depth. The deposited dose was measured by collecting aerosol from inhaled and exhaled air stream on filters, which were analyzed for radioactivity. Lung imaging was performed using a planar GC (posterior). Ratios of GC counts to deposited dose (GC/DD) were similar after FB and AL administration, but twofold lower after AW administration (p < 0.01). Associated attenuation correction factors (ACF) were 2.5 +/- 0.5 (FB), 2.2 +/- 0.4 (AL), and 5.5 +/- 1.6 (AW, p < 0.01). Both GC/DD and ACF were highly correlated to the aerosol distribution index (central to peripheral ratio, C/P). After shallow bolus administration there was a negative correlation between body mass index and GC/DD. Inhalation of radioaerosols used in medical diagnosis and therapy in combination with high central airway deposition results in an underestimation of the deposited dose based on planar GC imaging. The aerosol distribution index C/P may provide one suitable indicator for corrections, which should be confirmed in future studies by individual attenuation analysis based on radiotracer transmission measurements.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Tc-99m aerosol; Technegas; bolus inhalation; attenuation correction; lung; airways; regional deposition; ultrafine particles; respiratory-tract; lung; clearance; scintigraphy; attenuation; healthy; quantification; mucociliary
Language
Publication Year
2009
HGF-reported in Year
2009
ISSN (print) / ISBN
0894-2684
e-ISSN
1557-9026
Quellenangaben
Volume: 22,
Issue: 1,
Pages: 45-54
Publisher
Mary Ann Liebert
Reviewing status
Peer reviewed
Institute(s)
Institute of Lung Health and Immunity (LHI)
POF-Topic(s)
30202 - Environmental Health
Research field(s)
PSP Element(s)
G-520200-001
G-505000-002
G-505000-005
G-505000-002
G-505000-005
Scopus ID
65349118997
PubMed ID
18844481
Erfassungsdatum
2009-07-09