Möller Winfried, Felten Kathrin, Meyer Gabriele, Meyer Peter, Seitz Jürgen, Kreyling Wolfgang G
Helmholtz Zentrum München-German Research Center for Environmental Health, Clinical Cooperation Group Inflammatory Lung Diseases, Gauting and Neuherberg, Germany.
J Aerosol Med Pulm Drug Deliv. 2009 Mar;22(1):45-54. doi: 10.1089/jamp.2007.0664.
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 (99m)Tc 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.
吸入放射性标记气雾剂的剂量通常使用γ（GC）相机成像来评估。由于肺结构复杂且不均匀，由软组织、胸廓骨骼、血管和气道组成，合适的衰减校正系数难以评估，且估计剂量具有很高的不确定性。在11名健康志愿者中，将100毫升由直径100纳米的（99m）Tc放射性标记碳颗粒（锝气体）组成的气溶胶团分别靶向气道（AW）或800毫升肺容积深度（肺泡，AL）。此外，将750毫升全呼吸（FB）的气溶胶吸入至800毫升肺容积深度。通过在滤器上收集吸入和呼出气流中的气溶胶来测量沉积剂量，并对滤器进行放射性分析。使用平面GC（后位）进行肺部成像。FB和AL给药后，GC计数与沉积剂量的比值（GC/DD）相似，但AW给药后降低了两倍（p<0.01）。相关的衰减校正因子（ACF）分别为2.5±0.5（FB）、2.2±0.4（AL）和5.5±1.6（AW，p<0.01）。GC/DD和ACF均与气溶胶分布指数（中央与外周比值，C/P）高度相关。浅推注给药后，体重指数与GC/DD之间呈负相关。在医学诊断和治疗中使用的放射性气溶胶吸入与高中央气道沉积相结合，会导致基于平面GC成像低估沉积剂量。气溶胶分布指数C/P可能提供一个合适的校正指标，未来研究应通过基于放射性示踪剂传输测量的个体衰减分析来证实。
