ADVERTORIAL material which covers the front of the photodiode , this effectively works in the same way as the intensifying screen in a traditional X-ray cassette . The scintillation material emits light when stimulated by radiation . The indirect stage of the conversion is then the transmission of this light by the photodiode into an electrical signal . In comparison to direct conversion DR receptors , the ‘ extra layer ’ allows a lower exposure to be used when acquiring an image . The increase in number of layers ( or times the information is ‘ processed ’) before an image is generated also results in a slight loss of resolution . Therefore DR receptors utilising indirect conversion will inherently result in images with lower resolution than direct conversion DR receptors .
DR FREQUENTLY ASKED QUESTIONS
Which should I choose ? Historically , indirect conversion receptors have been preferred due to the lower radiation dose required . Direct conversion is now becoming more popular as the sensitivity of TFT layers improves , however , there have been more issues related to the stability of the direct conversion systems ; some detector panels fail if they are taken outside certain temperature ranges ! Currently indirect conversion is still more common in human medicine , with very few direct panels in use .
Why do some panels cost more than others ? Very often quality is the answer . In the same way a television or computer monitor is made , there will always be a number of ‘ duff ’ pixels on a DR panel . When quality assurance is applied , they are then categorised by the failure rate , i . e . the less failed pixels , the lower the failure rate and the higher quality the panel . When calibrating a detector panel , the DR system builds up a map of defective pixels and then hides them , so that you don ’ t see them on the image , but this doesn ’ t mean they are not there ! Fundamentally , higher resolution panels are harder to make , so this will impact cost .
Direct blows from a horse ’ s hoof or repeatedly being dropped onto a hard surface will take its toll . Most are designed to hold the weight of a human patient with the weight spread evenly over the plate . The higher risk of damage comes when pressure is applied to a point . A kick is likely to be most damaging , but this risk can be reduced by using a plate protector .
Why does image quality change over time ? All DDR technologies will age over time as radiation can be harmful to electronics , eventually affecting the sensitivity of a system . This impact can be reduced by servicing , performing gain calibrations and offset recalibrations . This will also help with any pixel drop out that has occurred over time .
Why does it take so long to repairs plates ? Unlike repairs to most systems , which may be possible via computer remote , or in-house if electrical , or maybe a simple part replacement , the repair of a DR receptor panel requires a very specific environment ( sterile , static-free , dust-free and airlocked ) and technical skill level . This level of repair is typically only available direct from the panel production facility .
IMV imaging supplies a variety of fixed and portable DR systems into the South African market , all with specialist vet software and pricing options to fit your practice best . Contact us via our website http :// www . imv-imaging . co . za / for more information , or call Tim on 082 616 4685 .
Why does temperature matter ? All DDR panels are sensitive to temperature changes and this can affect the required X-ray exposure . To compensate for this , many systems will recalibrate if they detect a temperature change , however , all will perform less well in extreme cold because they were originally designed to be used at room temperature . Therefore , we recommend never leaving them in unheated vehicles overnight . It is also worth remembering that wireless systems rely on batteries within the plate . Modern , rechargeable batteries have improved a great deal , but still don ’ t cope well with the cold which can cause rapid loss of charge .
Why do they break when dropped ? The scintillation layer is normally coated onto a sheet of glass . It needs to be affixed to a thin , strong clear surface and glass functions well . The panel can cope with normal use and much work has gone into making them drop resistant , but they are very complex inside .
Issue 02 | MAY 2018 | 23