IMAGE
INTENSIFIERS

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Over a period of time, all components in an imaging system begin to wear out.  This results in degradation of signal to noise ratio, geometry, spatial resolution and contrast resolution.  These usually are caused by deterioration of the image intensifier, optical system, TV camera tube or monitor and combinations thereof.  The philosophy of “Don’t fix it if it isn’t broken” leads most engineers to refrain from replacement/repair until a radiologist comments on poor image quality.  But pro-active tweaking and replacement can greatly reduce and control downtime.

Under normal use, a CRT loses brightness as the phosphor wears and the electron gun output weakens.  You may be able to stay one step ahead by following the recommended guideline of replacing your monitor’s CRT every 48 months.  It is also recommended that the camera tube be adjusted every eight months and replaced every 30 months.

An image intensifier should be replaced when the conversion factor (gain) drops below 100 on the largest field size when the II is used in a general R/F room - and below 120 in a vascular or cardiac suite. When replacing an II, you should check the adjustment of the ABC. If you do not, the input dose may be too low and result in more quantum noise. This quantum noise could be perceived as a noisier or grainier image.

We have found that many engineers do not reload their image tubes in-house anymore. The new metal II’s have a very delicate input window that is .7mm in thickness.  Therefore the engineers have found that an exchange or a reload of the original housing is the way to go.  So if you have a GE, Philips, Siemens, Toshiba, Picker (Marconi), Machlett, CGR, Shimadzu, the TREX family, or any other II we should be able to offer a replacement for it.

When you need to replace your GE II, Imaging Affiliates can supply the original Thomson II. Not only will this return your II to its original performance, but you might be able to replace it with a higher performance, next generation Thomson II.  Also, Imaging Affiliates should be able to supply you with new replacements for most of the Toshiba, Siemens and  Philips Image Intensifiers.  If we are unable to supply the original II, most housings can be retrofitted to accept an equivalent image tube. The power supply mounting location on the retrofit may be different from the original but should not affect operation. The new power supply location may be better for adjustment, safer and less susceptible to noise.