A system for analyzing biological structures by photon absorptiometry is disclosed, including a radiation source emitting photons and at least one source filter which operates to reduce the emission of high energy photons, thereby creating a sharp drop-off at the high end of the detected energy spectrum. The filter radiation is received by a detector which determines the spatial intensity of the radiation over the image area and preferably has a characteristics response which is relatively insensitive to low energy photons, such that the source filter and detector cooperate to measure the intensity of photons within a narrowed band of energy levels.

A gamma camera within a signal generating system encompassing a stage converting an image which is to be photographed into an electron image, following which there is a locating or position-finding system from which signals emanate which facilitate the pictorial reproduction of the incident radiation.

This invention provides a high-resolution, position-sensitive, proportional-counter for ionizing radiation emanating from a surface source of ionizing radiation. There is provided a counting chamber means having an open entrance window on one side of and spaced from the source of ionizing radiation, and an anode counting wire on the other side of the open entrance window. Also, there is provided a counter wall cathode, having a delay line read-out opposite to the entrance window and spaced from the anode. A means, including several orifices for flushing a counting gas through the counting chamber means and out of the open entrance window between the source and the open entrance window, produces a stabilizing counting gas layer that does not mix with the surrounding air. This prevents the sample from being completely surrounding air. This prevents the sample from being completely enclosed so as to be charged up electrostatically. An electronic means is connected to the delay line for providing the read out of the desired high-resolution, position-sensitive, proportional-counter information corresponding to the ionizing radiation emanating from outside the open entrance window.

A position sensitive multiwire proportional counter with integral delay line including a support carrying a plurality of anode wires and at least one cathode wire spaced in a predetermined relationship from the anode wires within the active volume of the counter to form an integral delay line. The counter is filled with a gas which ionizes upon interaction with ionizing radiation, the ionization of the gas being enhanced by the positive anode, such that an electrical charge is thereby induced in the cathode wire. Sensing of elapsed time between receipt of the induced charge at opposing ends of the cathode wire is utilized to determine the desired radiation positional data.

A compact single- or multi-channel radiation detector capable of sending forth a large and stable output signal by being operated in a proportional region which comprises a single or a plurality of electrode assemblies each prepared by inserting between a pair of mutually facing parallel high voltage electrodes an electric charge-collecting electrode having a plurality of metal wires spatially arranged in a plane parallel with said paired high voltage electrodes, and wherein the single or plural electrode assemblies are received in a case provided with a radiation inlet section and filled with a gaseous element mainly consisting of a rare gas such as argon or xenon.