X-Ray imaging camera with 100mm x 100mm imaging plate

[Fraser]

I have been gifted a very nicely made X-Ray imaging camera so thought I would share some initial pictures of it with you.

The camera is used in a LUNAR PIXI bone density measuring equipment that used two levels of X-Ray energy to create a bone density profile for the DUT. The DUT may be part of a person or a lab specimen/rodent etc.

The technology within the unit will be revealed when I take a look inside. Sadly I have zero time to do this at the moment but I can describe what will be inside from my past experience.

The 100mm x 100mm aperture at the front of the camera assembly is the fluorescent imaging plate with integral aluminium filter. This plate glows when illuminated by X-Ray. The DUT casts a shadow on the plate, just like in conventional film imaging techniques. In order to create an electronic version of the image that appears on the plate, a camera of some description is required. A camera of the type used in this assembly requires an optical block. The optical block consists of one or more lenses and a 45 degree high quality glass mirror. The mirror is important as it enables the X-Ray energy to pass through it without illuminating the sensitive electronics of the camera and CCD imaging chip. The image is reflected towards the camera, but the X-Rays are not. This offsetting of the camera reduces the need for screening or leaded glass in the X-Ray energy axis of travel. The optical elements in the lens(es) carefully match the cameras CCD chip to the 100mm x 100mm fluorescent plate with correct focus and the minimum of distortion.

The actual camera may take many forms depending upon the application. In mail scanning X-Ray machines fine detail is not always essential so quite low resolution cameras are used. These are often nothing more than a sensitive monochrome CCTV camera. No image intensifier is needed or used in that application. Higher resolution cameras may be used with PC capture cards or dedicated SBC's to provide much finer detail to the user. The limit of the resolution achievable is ultimately controlled by the X-Ray tube spot size, fluorescent plate grain, camera optics and the camera specifications. The LUNAR camera assembly is not of the simple CCTV type. As can be seen in the pictures, it appears to be a very well constructed piece of hardware. Whether it is bespoke to the LUNAR PIXI equipment is not known. Resolution is not known but will be available via the LUNAR PIXI brochure I am sure.

Having removed the camera from the optical block, I was able to see the rear of the lens and the CCD imaging chip. The CCD has what appeared to be a 16:9 aspect ratio. No makers ID is to be seen on the camera but the PCB's may reveal useful information when I remove the covers. The camera is powered by 5V, +15V and -15V via a 9 way Sub-D connector. Communications and control are via a large SCSI like connector and are expected t be fully digital due to the resolution requirement. Two LED indicators are also present on the rear of the camera but their purpose is not known.

It is sadly unlikely that I will be able to drive the camera unless it uses a documented data interface, which is unlikely, but not impossible. Sadly all of the control hardware has been destroyed so no clues there.

Well that is all for now folks. I will add pictures of the internal parts just as soon as I find the time.

Fraser

[Fraser]

A comparison of the LUNAR PIXImus and the Faxitron MX-20 is available here:

http://www.sdu.dk/en/om_sdu/institutter_centre/klinisk_institut/forskning/forskningsenheder/ortopaedkirurgi/forskningsomraader/eksperimentel+forskning/oevrigt+imaging+udstyr


Some information on the unit here

http://www.bonedensitymachines.com/ge-lunar-bone-density/ge-lunar-pixi-densitometer-machine/

and here :

http://www.piximus.com/

Pixel size is 0.2mm which provides a camera resolution of approximately 500 x 500 pixels. Not as high as I had expected and significantly less than my Faxitron MX-20's 2048 x 2048 pixels covering the same imaging area. Bone density measurement obviously does not need very high resolutions to achieve an adequate result.


I attach a picture of a Pixi (aka PIXImus) unit from which the camera originates.

Fraser