Measurements of the Human Anterior Chest Wall by Ultrasound and Estimates of Chest Wall Thickness for Use in Determination of Transuranic Nuclides in the Lung

The low energy photons on which the in vivo detection of plutonium isotopes and americum-214 is based are severely attenuated in body tissues. To assess the activity of these radionuclides in the lungs by external measurements it is necessary to estimate or measure the thickness of tissues overlying the lungs. It is also desirable to distinguish between muscle and adipose tissues in the chest wall because of the difference in their attenuation properties. Diagnostic ultrasound machines developed for medical use are suitable for this purpose. Ultrasonic measurements of check wall thickness have been made at this laboratory since 1978. This paper summarises our experience of these measurements and describes our present procedure for making the measurements. The concept of 'equivalent muscle chest wall thickness' is introduced and a method for calculating the parameter is given. Both chest wall thickness and equivalent muscle chest wall thickness have been found to correlate well with Quetelets Index (weight divided by height squared). Residual correlations with other parameters have been examined. Empirical formulae are given that can be used to predict the chest wall thickness and equivalent muscle chest wall thickness of a subject of given weight, height and age.