The Scintillation Counter
The scintination counter is a relatively new instrument for the detection and measurement of nuclear and atomic radiations. Light produced in a fluorescent material by the incident particle or quantum Is picked up by a photomultiplier tube. The resultant photoelectric emission is amplified in the photomultiplier by a series of secondary-emission stages. This paper is a review of the present state of knowledge regarding the characterstics of the counter and the details of Its operation.
Crystal counters.
This paper gives a general account of the recently discovered conduction type counters. Among the topics discussed are: The nature of the counting phenomenon, preparation of crystals, types of useful crystals, experimental technique, polarization, speed, limitations and comparisons with other types of counters.
New Low-Profile Applicators for Local Heating of Tissues
A new type of low-profile applicator is described giving efficient power transfer to tissue with low leakage. It consists of a resonant element spaced from a ground plane by low-loss material having high relative permittivity and some relative permeability. This combination is covered by similar material which can be placed in direct contact with the tissue to be heated, or separated from it by a water bolus as required. Laboratory measurements using phantom materials show that these applicators are well matched and produce well defined and relatively uniform heating profiles. Applicators having maximum dimensions of 3-15 cm covering the frequency range 1000-100 MHz, respectively, are described. Penetration depths of at least 4 cm at 100-200 MHz are achieved. Tests on anesthetised pigs and some clinical assessment have confirmed the usefulness of this compact low-frequency type of applicator and have shown that performance compares favorably with that of other recently reported types. The design can be optimized for treatment of specific sites, and suitable choice of dimensions and electrical characteristics of the layer material allow the low-profile concept to be extended over a wide range of operating frequencies.