公开(公告)号：US4695731A

公开(公告)日：1987-09-22

申请号：US762008

申请日：1985-08-02

Applicant: Keith J. Larkin

Inventor： Keith J. Larkin

IPC: G01T1/185 ,  G01T1/29 ,  H01J47/00 ,  H01J47/02

CPC classification number: H01J47/02 ,  H01J47/005

Abstract: To enable an ionization chamber used for measuring the intensity of a beam of ionizing radiation, for example an electron beam produced by a linear accelerator and used for radiotherapy, both to give an output signal which is independent of ambient pressure and temperature and to present a low weight of scattering material per unit area to the beam, the chamber is of flexible construction so that the volume of gas in it adapts to ambient pressure and temperature, and such that the weight of gas in the active region between the electrodes per unit area remains substantially constant. Suitably, the electrodes are conductive layers on flexible plastics sheets, an outer annular portion of one sheet providing a flexible connection between two opposed chamber wall portions which remain substantially planar and parallel; the proportional change (.DELTA.V.sub.1 /V.sub.1) in a volume bounded by the opposed wall portions and including the active region equals the proportional change (.DELTA.V.sub.2 /V.sub.2) in the remainder (V.sub.2) of the internal volume.

Abstract translation: 为了实现用于测量电离辐射束的强度的电离室，例如由线性加速器产生并用于放射治疗的电子束，可以给出独立于环境压力和温度的输出信号，并呈现 每单位面积的散射材料重量与梁的重量相差，室内结构柔软，使得其中的气体体积适应环境压力和温度，并使每单位面积电极之间的有源区气体重量 保持基本恒定。 适当地，电极是柔性塑料片上的导电层，一片的外环形部分提供两个相对的室壁部分之间的柔性连接，其保持基本平坦和平行; 由相对的壁部分限定并包括有源区域的体积中的比例变化（DELTA V1 / V1）等于内部体积的余数（V2）中的比例变化（DELTA V2 / V2）。