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EP0196138A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Image-detector for high-energy photon beams

Assignee: Antoni van Leeuwenhoek Hospital
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Filing: 1986-03-21
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Granted: —
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Expires: 2006-03-21
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Abstract

Abstract Image-detector for depicting differences in intensity in high energy photonbeams with the aid of a photon-sensitive element and method for producing such pictures. This kind of detectors are used for treating tumors with the said irradiation. The photon-sensitive element is an ionisation chamber, consisting in the main of two mainly equivalent plates of an electrically insulating material, which are attached to each other by a ring-shaped electrically insulating part as a divider, whilst the outer walls of both plates are covered with electrically conductive material, whereby one of the plates is equipped with a number of parallel high voltage electrodes over a central part of its inner wall and the other plate is equipped over a central part of its inner wall with a number of parallel ionisation current electrodes which extend perpendicularly towards the high voltage electrodes, whilstthe inner walls of both plates around the central parts are covered with an electrically conductive material and a liquid dielectric is situated in the space between the plates. The liquid dielectric preferably is a saturated hydrocarbon.

Inventors

  • 👤 Harm Meertens

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-08 12:17
CPC Classifications
H; H01; H01J; H01J47/00; H01J47/02; H01J47/028

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 153 words
Image-detector for depicting differences in intensity in high energy photon beams with the aid of a photon-sensitive element, characterised in that the photon-sensitive element is an ionisation chamber, consisting in the main of two mainly equivalent plates of an electrically insulating material, which are attached to each other by a ring-shaped electrically insulating part as a divider, whilst the outer walls of both plates are covered with electrically conductive material, whereby one of the plates is equipped with a number of parallel high voltage electrodes over a central part of its inner wall and the other plate is equipped over a central part of its inner wall with a number of parallel ionisation current electrodes which extend perpendicularly towards the high voltage electrodes, whilst the inner walls of both plates around the central parts are covered with an electrically conductive material and a liquid dielectric is situated in the space between the plates.
Claim 2
Dependent Claim 153 words
Image-detector for depicting differences in intensity in high energy photon beams with the aid of a photon-sensitive element, characterised in that the photon-sensitive element is an ionisation chamber, consisting in the main of two mainly equivalent plates of an electrically insulating material, which are attached to each other by a ring-shaped electrically insulating part as a divider, whilst the outer walls of both plates are covered with electrically conductive material, whereby one of the plates is equipped with a number of parallel high voltage electrodes over a central part of its inner wall and the other plate is equipped over a central part of its inner wall with a number of parallel ionisation current electrodes which extend perpendicularly towards the high voltage electrodes, whilst the inner walls of both plates around the central parts are covered with an electrically conductive material and a liquid dielectric is situated in the space between the plates.
Claim 3
Dependent Claim 28 words
Image-detector according to claim 1, characterised in that the liquid dielectric is a saturated hydrocarbon of the type C H , cyclopentane, cyclohexane or tetramethylsilane. n 2 n+2
Claim 4
Dependent Claim 13 words
Image-detector according to claim 2, characterised in that the dielectric is 2.2.4 trimethylpentane.
Claim 5
Dependent Claim 81 words
Method for depicting differences in intensity in high energy photon beams with the aid of an image-detector according to claims 1 or 2, characterised in that the high voltage electrodes are provided with voltage separately and in a previously determined series of electrode combinations with the aid of a controlled high voltage selector system, whereby currents by the ionisation current electrodes are separately measured with the aid of a multi-channel electrometer amplifier circuit and whereby the ionisation current is digitally integrated.
Claim 6
Dependent Claim 49 words
Method according to claim 3, characterised in that the ionisation current which is measured is corrected for a difference in zero adjustment of the channels with high voltage turned off, and that the ionisation current which is measured is corrected for differences in sensitivity of the separate matrix cells.

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