Compton-scatter tissue densitometry: calculation of single and multiple scatter photon fluences.
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Absorptiometry, Photon↗
Biomedical subjects
J J Battista
Publications and source records attributed to J J Battista.
Compton scatter imaging of transverse sections: corrections for multiple scatter and attenuation.
The electron density (e cm-3) of a tissue sample can be determined by measuring the fluence of photons which it Compton scatters from a narrow incident beam of X- or gamma-radiation. This technique has been applied successfully to diagnostic denistometry (bone, lung), and less successfully to whole body tomography. In this work, the physics of Compton scatter tomography is examined with emphasis on transverse section scanning. The two major limitations of the scatter technique, attenuation of the single scatter photon fluence (of interest), and contamination of this fluence by multiply-scattered photons, are studied and corrective procedures are proposed. The methods described are applied to a simple test phantom; it is concluded that transverse images with an electron density precision of approximately 5% are possible.
Air↗
Implications of computed tomography for inhomogeneity corrections in photon beam dose calculations.
Patient inhomogeneity information is investigated for use in radiotherapy planning. Absorbed doses measured in a phantom are compared to doses calculated for photon beams using various treatment planning inhomogeneity correction methods. Delineation of inhomogeneities with a spatial resolution of 5 mm and with an electron density accuracy of 2% in usually sufficient to allow doses to be calculated with a mean accuracy of better than 2% for 60Co and 3% for 25-MV x rays if the authors' Equivalent Tissue-Air Ratio Method is used.
Cobalt Radioisotopes↗
Modified transit dosementer system for 60Co rotational therapy.
The transit dosemeter has been used in obtaining inhomogeneity corrections for 60Co rotational therapy. A modified approach is presented which features a rapid electronic system for determining the average tissue-air ratio (TAR) for a 360 degree rotation. Experimental results and early clinical experience show that this system is capable of providing a TAR value directly, and more rapidly. It can be readily incorporated in a therapy system which already includes a transit dosemeter.
Cobalt Radioisotopes↗