Radiant energy – Invisible radiant energy responsive electric signalling – Plural signalling means
Patent
1998-01-29
2000-07-11
Hannaher, Constantine
Radiant energy
Invisible radiant energy responsive electric signalling
Plural signalling means
25036301, 250367, 250366, 2503851, G01T 117, G01T 1185, G01T 120
Patent
active
060876646
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for measuring the radiation depth or penetration of a radiation and to a measuring device, comprised of two sensors, for measuring the radiation dose.
BACKGROUND OF THE INVENTION
It is known to determine the energy of an electron beam by measuring the penetration depth of the radiation in an object with an ionization chamber or with an arrangement of a plurality of ionization chambers. This process is time consuming and expensive from a measurement technology point of view.
A measurement device comprised of two sensors for measuring radiation dose is also known from German Patent application Ser. No. 195 03 647.6-33. This however is not provided for the measurement of penetration depth but rather for the measurement of a tissue equivalent dose.
OBJECT OF THE INVENTION
The object of the invention is to provide a process for the rapid and simple measurement of the penetration depth of an (ionizing) radiation as well as the provision of a device for carrying out the process.
SUMMARY OF THE INVENTION
According to the invention, the radiation depth is measured by measuring the radiation dose along a radiation path up to its penetration depth, measuring the radiation dose in a volume element within the radiation path forming a dose independent quotient of both measurements and determining the penetration depth of the radiation quotient based upon reference values.
Both sensors can have a three-dimensional extent parallel to or along a straight line and one of the sensors can encompass a longer stretch along the line than the other sensor. The difference in the stretches can amount to at least 20 mm.
For carrying out the process, the radiation dose is measured (in an object) along the radiation path up to the penetration depth. It is sufficient to limit the measurement to a stretch at the end of the radiation path. It is thus not required to fully pick up the radiation. Furthermore, the radiation dose is measured in a volume element located within the radiation path. So that no artifacts are detected based upon intensity fluctuations of the radiation, it is advantageous to carry out this and the aforedescribed measurement simultaneously.
Advantageously, the measurements are carried out with sensors of the same type to obtain a dose independent value upon quotient formation. Otherwise, approximations must be taken into consideration, or compensation calculations must be carried out.
In conjunction with the two measurements, a dose-independent quotient is formed from both measured values. Based upon reference values, the penetration depth of the radiation in the object can be finally determined.
The penetration depth is a measurement of the energy of the radiation. As a consequence, the process enables determination of the energy of a radiation beam of high energy corpuscular radiation (e.g. electrons, protons, ions, neutrons). The process is suitable, inter alia, for routine monitoring of the energy of an electron beam used in radiation therapy in an energy range between 2 an 25 MeV.
A measuring device for carrying out the process is comprised of two sensors (1), (2) for measurement of the radiation dose. These have a three dimensional range which is oriented parallel to or along a straight line. One ("long") sensor (2) covers a longer stretch along the line than the other ("short") sensor (1).
The purpose of this arrangement is that radiation which runs parallel to the line is registered by the sensors upon suitable positioning of the device in the radiation path. It is then important that the longer sensor (2), by contrast to the shorter sensor (1), register the radiation up to its penetration depth. Furthermore, upon a suitable positioning in the radiation path, a sufficiently different sensor signal should be generated between the shorter sensor (1) and the longer sensor (2). The length difference or the difference with respect to the covered stretches parallel to the line are selected in accordance with these requirements. The requirements ar
REFERENCES:
patent: 4267446 (1981-05-01), Brown et al.
Conception of an Ionising Radiation Detection Scheme Based on Controlled Light Induced Annealing of Silica Fibres, by Vassilopoulos et al., 8049j IEE Proceedings-J 140(1993) Aug., No. 4, Part J, pp. 267-272.
Buker Harald
Gripp Stefan
Hasing Friedrich-Wolfgang
Dubno Herbert
Forschungszentrum Julich GmbH
Hannaher Constantine
Israel Andrew
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