Abstract: In order to facilitate the display and evaluation of data acquired while irradiating a body, e.g. a patient undergoing radiation therapy, a dosimetry system has a plurality of sensors for disposition on, in or near the body to be irradiated and connected to a sensor reading instrument which is interfaced with a display system, for example a personal computer, which is arranged to display, in use, one or more representations, for example drawings or photographs, of the body to be irradiated, along with the positions and the dose data for those specific locations where the dosimeter sensors were placed.

Abstract: In a dosimeter probe comprising a semiconductor diode or a field effect transistor for monitoring levels of radiation during medical procedures, such as the treatment of tumors, the transistor or diode is fabricated epitaxially upon a surface of a substrate and a dummy die, i.e., a slab of material similar to that of the substrate, is positioned adjacent the substrate surface so as to overlie an active region of the transistor or diode and a relatively large area of the substrate surrounding the active region. The arrangement is such that, whatever the direction from which the radiation is incident upon the active region, its path through the device before arriving at the active region will have similar characteristics to the path the radiation takes upon leaving the active region.

Abstract: An insulated gate field effect transistor dosimeter has a source and drain defining a channel region, a floating gate having a first portion extending over the channel region, and a second, larger portion extending away from said region, a control gate having at least a portion thereof overlapping a first part of the floating gate, and a charging gate overlapping a second part of the floating gate. The area of the second part of the floating gate is much smaller than the area of the first part, and the charging gate is separated from the channel region by the control gate. The dosimeter is charged, before irradiation, by connecting the source, drain and control gate to a common ground and applying a potential difference between the charging gate and the common ground. The charge is supplied to the floating gate by a path which does not require a significant electric stress to be created in the region of the gate oxide and the channel.

Abstract: This invention describes a flexible radiation probe which has a pair of insulated gate field effect transistors integrated into the same substrate each having a gate, source and drain. The transistors are mounted at the end of a flexible circuit board. The flexible circuit board has conductive tracks which connect the gate, source and drains of each of the transistors to a connection at an opposite end of the flexible circuit board. This connection end may then be connected to a suitable differential biasing circuit for biasing the transistors, and a circuit for reading the differential threshold voltages of the transistors. This differential threshold voltage being indicative of radiation received by the transistors when exposed in the bias mode. The flexible circuit allows the probe to be used in catheters or similar medical equipment.

Abstract: The invention is a radiation dosimeter and method of operation of its elements comprising a pair of silicon insulated gate field effect transistors integrated into the same substrate, each having a gate, a source and a drain. The dosimeter includes apparatus for measuring a first differential threshold votlage between the transistors, appartus for forward biasing the gate of the first transistor and inhibiting operation of the second, while allowing both to be subjected to ionizing radiation, and apparatus for measuring a second differential threshold voltage between the transistors following the irradiation. The first differential threshold voltage can be subtracted from the second to obtain a measure of the radiation dosage. Threshold drift and offset is thereby substantially eliminated.