Hal O. Anger

Wedge-and-strip anodes for centroid-finding position-sensitive photon and particle detectors

We discuss new anode geometries, employing position‐dependent charge partitioning, which can be used with microchannel plates, planar proportional counters, and mesh dynode electron multipliers to obtain a two‐dimensional position signal from each detected photon or particle. Only three or four anode electrodes and signal paths are required, yet images comprised of a number of detected events have little geometric distortion and the resolution is not limited by thermal noise inherent in resistive sheet anodes. We present an analysis of the geometrical image nonlinearity in the relationship between event centroid location and the charge partition ratios. Fabrication and testing of two wedge‐and‐strip anode systems are discussed. Images obtained with EUV radiation and microchannel plates that verify the predicted performance of this readout system are shown. We emphasize that the spatial resolution of the wedge‐and‐strip anode is in no way limited by the coarseness of the anode conductor pattern. The resolu...

Gamma‐Ray Detection Efficiency and Image Resolution in Sodium Iodide

Photoelectric, Compton, and photopeak efficiencies have been calculated at several gamma‐ray energies for large flat sodium iodide crystals in which the thickness ranges from ⅛−2 in. Also, the loss of position resolution by gamma‐ray scattering within the scintillator is calculated, since this is of interest in the design of gamma‐ray imaging devices like the scintillation camera. An examination of the data shows the advantage of using low energy gamma rays for imaging whenever possible. They are efficiently detected by solid sodium iodide scintillators ½ in. thick, and there is little loss of resolution due to scattering of gamma rays in the scintillator. In the higher energy range, a choice must be made between a thin scintillator with its relatively good position resolution and low detection efficiency, or a thick crystal with higher detection efficiency and less satisfactory resolution.

BONE BLOOD FLOW SHOWN WITH F18 AND THE POSITRON CAMERA.

Development of the positron camera has made it possible to rapidly obtain pictures of the distribution of radioactive fluorine 18 in the living animal or human being. The distribution of F18 admini...

HUMAN BONE MARROW DISTRIBUTION SHOWN IN VIVO BY IRON-52 AND THE POSITRON SCINTILLATION CAMERA.

Radioactive iron, which concentrates in erythropoietic marrow, is given intravenously, and 16 hours later pictures of its distribution are taken with the positron camera. The instrument is an imaging device that produces pictures of the distribution of positron-emitting nuclides without scanning. Wide variations in the distribution of marrow are found in various diseases.

Simple and safe bedside method for serial measurement of left ventricular ejection fraction, cardiac output, and pulmonary blood volume.

A simple, safe method for bedside measurement of left ventricular function and pulmonary blood volume has been developed. A single scintillation probe positioned over the mid-left ventricle records the passage of bolus of radionuclide (ll3mIn) injected into the superior vena cava, from which the left ventricular ejection fraction can be determined after proper background correction. ll3mIn, half-life I-7 hours, easily prepared from a commercially available generator, rapidly binds to plasma transferrin and can be used to determine blood volume and cardiac output. With cardiac output and left ventricular ejection fraction determined simultaneously, left ventricular end-diastolic volume can be calculated and pulmonary blood volume can be determined from pulmonary transit time and cardiac output. With this method, we have demonstrated stable and changing left ventricular function and pulmonary blood volume in a variety of clinical situations, e.g. myocardial infarction, pulmonary embolism, and severe pulmonary parenchymal disease. Blood volume and cardiac output so determined correlate well with standard techniques. The left ventricular ejection fraction determined by this method correlates well with this measurement obtained from left ventricular angiography. Loss of the pulmonary valley between the right and left ventricles has been demonstrated in severe pulmonary vascular obstruction (embolism), in severe bronchial obstruction, and as a result of massive right ventricular dilatation in the presence of normal pulmonary blood volume. This method, which can be frequently performed, has proved useful in serial evaluation of cardiac function at the bedside.

Scintillation Counters for Radioactive Sample Measurement

A gamma‐ray counter for liquid or solid samples is described. It uses an RCA 5819 phototube at room temperature with a thallium activated sodium iodide crystal in the shape of an annular ring. The gamma‐ray counting efficiencies of this counter for 2‐milliliter samples of Fe59, Co60, and I131 are about equal to the beta‐particle counting efficiency of a mica‐window G‐M counter when counting thin samples. When the counter is heavily shielded, the background is about 160 counts per minute. The phototube operating voltage is not critical since over a wide range of operating voltage the counting efficiency and background count change only slightly. A directional gamma‐ray counter is also described.

Tin-117m: Production, chemistry and evaluation as a bone-scanning agent

Abstract Cyclotron and nuclear reactor methods of producing 117mSn were compared. Reactor production gave the highest yield. Of several chelates studied, in rats 117mSn tartrate gave the highest bone uptake (55 per cent) with less than 5 per cent uptake in soft tissue. Because of a favorable half-life of 14 days and emission of 158 keV photons, 117mSn is considered as a possible bone-scanning agent. Scintillation camera and whole-body scan pictures show uptake of 117mSn-tartrate in bone of beagle dogs. Radionuclidic purity, chemical toxicity, and absorbed radiation dose are within limits acceptable for human use.

Production and chemical processing of Fe52 for medical use

Abstract A method is described for the production and chemical separation of radioactive Fe 52 for clinical use. Iron-52 in the form of ferrous citrate is being used to determine the distribution of erythropoietic bone marrow in both animal and human subjects with the positron scintillation camera. Detailed descriptions of the target preparation, cyclotron irradiation and chemical processing of the Fe 52 are given.

Liquid Scintillation Counting of Tritium and C14 Labeled Compounds

A liquid scintillation counter suitable for measuring H3 and C14 activities is described. A photomultiplier tube with a high sensitivity and signal‐to‐noise ratio is used, and is cooled to −10°C to further reduce the tube noise background. The phototube is mounted in a chassis containing its preamplifier, and the pulses are then led to a high‐stability amplifier scaler. The radioactive materials are dissolved in aliquots of a xylene solution containing p‐terphenyl (1.9 g/liter) and diphenylhexatriene (0.020 g/liter). Substances which quench the scintillations or color the scintillator solution cannot be counted by this method. A minimum of 4.3×10−10 curie of H3, or 1.8×10−11 curie of C14 may be measured by the counter.

Neurologic diagnosis using the 80-lens optical camera.

Article abstract This article describes the clinical application of the 80-lens optical camera in the diagnosis of cerebral infarction, subdural hematoma, intracranial tumor, and hydrocephalus. The 80-lens camera is a simple noncomputerized addition to the Anger scintillation camera that permits an estimation of the cerebral blood flow. The study is noninvasive and quick, minimizing the effect of movement artifact and showing areas of either increased or decreased blood flow. Abnormal tumor vessels appear, and subdural hematomas show brain displacement away from the skull edge. Interpretation of blood flow pattern is not affected by scalp or skull trauma, eliminating a source of error incurred with static scans.