Scintillator crystal radiation detector

#In invisible radiation systems such as x-ray, gamma ray and other systems utilizing invisible radiation, it is often necessary to employ devices for detecting the invisible radiation and converting it to another form of energy such as electrical signals which may more easily adapted and controlled for subsequent utilization in the systems.

#It has been common practice to employ an x-ray tube for producing an x-ray image and a fluoroscopic screen for detecting the x-ray image and converting it into a corresponding visible image. Also common in the art is the use of an image intensifier tube which has a fluorescent screen at one end which detects the x-ray image and converts it to a visible image, a photoemitter which converts the visible image to an electron image, and an output fluorescent screen which converts the electron image to a highly intensified visible image.

#Other known invisible radiation detectors include devices based on scintillator crystals combined with photomultiplier tubes. The scintillator crystal functions to convert the radiation to visible light with the light sensitive photomultiplier tubes converting this light to an electrical signal. Suitable scintillator materials include materials such as sodium iodide, calcium fluoride, bismuth germanate or the like.

#The above and other objectives of the invention will become apparent from the following description taken in connection with the accompanying drawings, wherein:

#FIG. 1 is a diagrammatic illustration of a system for scanning a subject with invisible radiation, including detecting means embodying the invention;

#FIG. 2 is an isometric view of a detector embodying the invention;

#In radiating systems such as computerized tomographic x-ray scanning systems, for example, it is important that detectors be utilized which will efficiently receive an x-ray beam of predetermined cross-sectional configuration and convert the beam to a corresponding electrical signal. Such an exemplary system is disclosed in FIG. 1 and comprises, briefly, an x-ray tube 10 which produces a beam 12 of x-radiation which passes through a subject 14. The beam 12 may be collimated by any suitable means so as to have a selected cross-sectional configuration. For example, the beam may be pencil shaped or fan shaped, as shown in FIG. 1.

#When the beam 12 passes through the subject it will be modulated by portions of the subject which have different x-ray absorption characteristics. The modulated beam impinges upon one or more detectors 16 in an array thereof, and, due to the fact that the flux or intensity of the beam is altered by the subject, the detectors 16 will consequently produce correspondingly different electrical signals.

#The detector array may be arranged in circular fashion around the subject as indicated by dotted line 18 or made to occupy segments of a circle, and the x-ray tube is mounted for movement in a circle 20 around the subject so that a slice of the subject is irradiated from all angles. Thus, from the signals generated by the detectors, an image can be produced as is well known in systems of the character.