A high‐sensitivity biomedical radiation probe which employs a fiber‐optic coupled NaI(Tl) scintillator as a detector is described. It was developed for in vivo counting of low‐energy 239Pu photons from material located in the tracheobronchial lymph nodes. This probe is 20 times as sensitive as a solid‐state probe (avalanche diode) previously developed for this application. Tests with 99mTc show a sensitivity more than 90 times greater than biomedical probes using DcTe of GaAs; however, the improved sensitivity is largely due to an increased sensitive volume. Probes were evaluated in animals and phantoms for detection of 239Pu and for location of lung tumors labeled with 111In.

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Waste Management Radioactive Shipments4.2 TECHNIQUES AND TRAINING . As the need for production of special nuclear materials for defense purposes diminished and long-time Hanford workers began to retire, the decision was made to document Hanford's experience with portable health physics instruments while the resources to do so were still available. In 1989, only a few health physics instrument specialists, radiation technicians and health physicists who worked at Hanford in the late 1940s still live in the vicinity. Of these, even fewer were available to assist in developing and reviewing this document. From those few, a team was selected and the document was developed. Most of the information about the instruments and their use and maintenance was obtained from the files of people who participated in the instrument program, and from the team of authors, who have a combined Hanford experience of over 200 man-years. To the degree possible, this review is presented chronologically to relate the changes in development and in practices for use in routine Hanford operations. Initial Techniques Technique Changes and Bases Records Generation Applications to Radiation Control SCOPE OF DOCUMENTSection 2.0 of this document summarizes the conclusions made concerning Hanford's portable health physics instruments and the users over a period of 45 years. Section 3.0 describes most of the instruments used during the past 45 years and provides some insight on how they work and how changes evolved. Section 4.0 discusses 1) typical instrument operation and maintenance in various types of facilities and 2) training and requirements for control of radioactive materials. Section 5.0 focuses on calibration and maintenance of health physics instruments over the past 45 years. It also provides some comparative instrument calibration data between older and newer instruments. Section 6.0 discusses the records that are generated for portable health physics instruments. Section 7.0 provides the conclusions reached by the authors of this document, and Section 8.0 provides the references. The remainder of this section discusses the types of radiations measured, the units that quantify them and the media needed to detect or measure them with electronic instruments, and summarizes the history of portable instruments and the evolution of instrument usage.1.1 RADIATIONS TYPES, UNITS, AND DETECTION MEDIATo understand how instruments detect radiation, it is necessary to generally understand the penetrating capabilities of nuclear radiations, the units that quantify them, and the media needed to detect or measure them with electronic instruments. This section provides simplified explanations of these factors. Types of Nuclear RadiationThere are four common types of nuclear radiation: alpha and beta particles, gamma rays, and neutrons.Alpha particles, composed of two protons and two neutrons, are released from an atom's nucleus during radioactive decay. Because no electrons are associated with them, they have a positive electrical charge. The heavies...

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Thin NaI (TI) scintillation counters were used for the assessment of body burdens in dogs exposed to 23QPu aerosol. Experiments were made with both a dog phantom and live dogs. Although the count rate was affected by changes in dog size and isotopic composition of the plutonium, the limiting factor in the accurate assessment of body burdens in our work was the distribution of the plutonium within the dog. Despite these problems, the body burdens of dogs have been determined with an accuracy of f 10% at 0.1 pCi levels, The average sensitivity obtained when counting the 17 keV X-rays emitted was 2.28 0.16 countsfminlnCi and was 13.3 i 1.1 counts/minfnCi when counting both the X-rays and 60 keV 241Am gamma rays. These sensitivities are based on body burdens determined by post-mortem alpha-counting analysis of the tissues of eight dogs that had previously been counted in the plutonium counter. In this study thirty exposed dogs were counted and body burdens ranging from 0.136 pCi to 3.12 pCi were observed.