In vivo detection, localization, and measurement of radionuclides in man: a detection system for the localization and measurement of small amounts of photon emitters. Progress report, September 1, 1979-December 1, 1980

The objectives of this research involve the design, development, and testing of a new type of photon detection system which can provide, simultaneously, magnitude and positional data regarding a radioactive source, without utilizing a high-Z collimator. This system employs the principle of active collimation, i.e., the geometric configuration of crystal elements results in certain members being shielded from oblique-angle rays, thereby providing spatial resolution characteristics. Inasmuch as events occurring in the promontory shielding crystals can be used to determine activity levels of the emitter, a greater counting efficiency is attainable than that with other currently available systems. Owing to optical and scintillation characteristics, and amplifier parameters, along with masking of the common PM tube, each of the five scintillation crystals in the detector configuration produces a separate, delineable spectral peak

In vivo detection, localization, and measurement of radionuclides in man: a detection system for the localization and measurement of small amounts of photon emitters. Progress report, September 1, 1979-December 1, 1980

The objectives of this research involve the design, development, and testing of a new type of photon detection system which can provide, simultaneously, magnitude and positional data regarding a radioactive source, without utilizing a high-Z collimator. This system employs the principle of active collimation, i.e., the geometric configuration of crystal elements results in certain members being shielded from oblique-angle rays, thereby providing spatial resolution characteristics. Inasmuch as events occurring in the promontory shielding crystals can be used to determine activity levels of the emitter, a greater counting efficiency is attainable than that with other currently available systems. Owing to optical and scintillation characteristics, and amplifier parameters, along with masking of the common PM tube, each of the five scintillation crystals in the detector configuration produces a separate, delineable spectral peak

In vivo detection, localization, and measurement of radionuclides in man: a detection system for the localization and measurement of small amounts of photon emitters. Progress report, September 1, 1978-May 15, 1979

The design, construction, and testing of a photon detection system which will yield, simultaneously, information proportional to both the magnitude and location of sources of radioactivity were undertaken. The operating principle of the detector system, active collimation, allows spatial resolution by utilizing the crystal elements themselves as the collimating device; hence a greater counting efficiency is attainable than with other currently available systems. The differences in characteristics of various crystals are utilized as the means of separating events occurring in each of five crystals. Mathematical processing of the counts from the individual crystals is then employed in conjunction with their geometric relationship to develop both positional data and to quantify the amount of radioactivity. By utilizing crystal detector elements in an active collimation configuration and incorporating them in an array which permits these crystals to be alternately advanced and retracted in a programmed, ordered manner, a high degree of spatial resolution is believed achievable without unduly compromising system sensitivity. Experiments were planned with a detector of optimized design to provide data on the ultimate performance that can be achieved with an N-element detector array. The experiments include development of the optimal crystal configuration, studies to ascertain the most efficient crystal shape, and the evolving of data processing techniques to translate detector response into precise source position information

In-vivo measurements of Pb-210 to determine cumulative exposure to radon daughters: A pilot study

The feasibility of measuring Pb-210 in vivo in the skulls of those individuals who have resided in homes with above average levels of radon/radon daughters, has now been successfully demonstrated. These values, when incorporated into metabolic models of Pb-210 in the body including other related physical parameters, can be used for the calculation of a realistic estimate of a resident's cumulative exposure to radon and its' decay products. Data are presented for 26 subjects exposed to higher than average concentrations of radon i.e. ranging from 10 to 120 pCi/l, for various periods of time. Their skeletal Pb-210 burdens are compared to measurement results of a population of individuals presumed to have been exposed to values which are more representative of average levels i.e. <1pCi/1. Results of a study to determine the biological retention of Pb-210 in the human skeleton for use in the metabolic model relating skull burdens of this nuclide to cumulative radon/daughter exposure, are also described. At the present time, our measurements, made over a period of 10 years, of an individual with a significant Pb-210 burden, indicate a biological half-time of approximately 57 years and an effective half-life of 16 years. 4 refs., 11 figs