Journal
JOURNAL OF AEROSOL MEDICINE AND PULMONARY DRUG DELIVERY
Volume 25, Issue -, Pages S10-S28Publisher
MARY ANN LIEBERT, INC
DOI: 10.1089/jamp.2012.1Su4
Keywords
lung deposition; planar imaging; gamma scintigraphy; orally inhaled products
Categories
Funding
- NIHR (National Institute for Health Research) UK Career Development Fellowship
- National Institutes of Health Research (NIHR) [CDF-2011-04-053] Funding Source: National Institutes of Health Research (NIHR)
- National Institute for Health Research [CDF-2011-04-053] Funding Source: researchfish
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Two-dimensional (2D or planar) imaging with Tc-99m radiolabels enables quantification of whole-lung and regional lung depositions for orally inhaled drug products. This article recommends standardized methodology for 2D imaging studies. Simultaneous anterior and posterior imaging with a dual-headed gamma camera is preferred, but imaging with a single-headed gamma camera is also acceptable. Correction of raw data for the effects of gamma ray attenuation is considered essential for accurate quantification, for instance, using transmission scanning with a flood-field source of Tc-99m or Co-57. Evidence should be provided of the accuracy of the quantification method, for instance, by determining mass balance.'' Lung deposition may be expressed as a percentage of ex-valve or ex-device dose, but should also be given as mass of drug when possible. Assessment of regional lung deposition requires delineation of the lung borders, using X-ray computed tomography, radioactive gas scans (Xe-133 or Kr-81m), or transmission scans. When quantifying regional lung deposition, the lung should be divided into outer (O) and inner (I) zones. A penetration index should be calculated, as the O/I ratio for aerosol, normalized to that for a radioactive gas or transmission scan. A variety of methods can be used to assess lung deposition and distribution. Methodology and results should be documented in detail, so that data from different centers may be compared. The use of appropriate methodology will provide greater confidence in the results of 2D imaging studies, and should allay concerns that such studies are qualitative or semiquantitative in nature.
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