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What is a Flat Panel Detector?

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Have you always wondered what the role of a flat panel detector is in x-ray technology?

Flat-panel detectors are in the category of thin-film X-ray digital radiography instruments similar to the image sensors utilized in automated photography and video. They are also mostly used in both projections of X-ray imaging and as a substitute to X-ray image intensifiers in fluoroscopy machinery.

The incident x-ray image has to be tested in both spatial and intensity capacities in a computerized imaging system. However, samples are collated as averages of the intensity over photographic elements or pixels within the spatial capacities. This is mostly in square shapes and spaced at equivalent intervals all through the plane of the depiction. 

Do you want to know more? Then let’s jump straight in.


I. What is a Flat Panel Detector in Radiology?

A flat panel detector (FPD) is a photographic component used in computerized radiography. It is similar to how a normal digitized camera uses a Complementary Metal-Oxide-Semiconductor (CMOS) sensor to acquire a light that passes through a lens and then converts it into an image. A flat panel detector converts X-rays passing through a shadow object into an image.

Flat-panel detectors (FPDs) are employed in direct digital radiography (DDR), and it’s basically for the translation of X-rays to light, known as indirect conversion or as a charge referred to as direct conversion, which allows for easy narration via a thin film transistor (TFT) array.


II. What does an X-ray Flat Panel Detector do?

It is noteworthy to examine the functionalities of a flat panel detector which brings us to this all-important question, what does an x-ray flat panel do?

Flat-panel detectors are employed in the manufacturing sectors for X-ray inspection or product scans, for instance, in the electrical manufacturing industry for detecting flaws and defects in electrical components. 

Furthermore, it is used in place of standard image intensifiers and film imaging plates. Its effectual capacity is greater than that of image intensifiers, with the visibility of the photos in real-time, without a need of removing the plate just to withdraw the pictures as with Imaging plates (IP).


III. What are Different Types of Flat Panel Detectors?

Flat Panel Detectors are of two major types, and they remain direct conversion (charge) and indirect conversion (light).

Direct conversion flat panel detectors use the amorphous selenium or any other type of photoconductors to trap X-ray photons and directly transform them into an electric charge. When the electric charge matches the high voltage bias electrode applied to the selenium layer, it culminates in generating the current commensurate with the irradiation’s potency. And then, a thin film transistor (TFT) is used to interpret the signals.

The Indirect conversion flat panel detector, on the other hand, converts X-rays into light via a layer of scintillator material which could either be cesium iodide or gadolinium oxysulfide. The amorphous silicon detector array lies behind the scintillator material. 

Comparable to a TFT-LCD display, lots of TFTs which hold pixels build a crisscross pattern in the scintillator layer, which lies on the glass. Like the image sensor chip of a camera, a photodiode is carried in each pixel, which helps generate an electrical charge proportional to the light formed by the scintillator layer part located at the fore of the pixel. The formed signals by the photodiode are ciphered and heightened by electronics around the sensor array to create a precise digital edition of the X-ray image.


IV. What are the Applications of Flat Panel Detectors?

The application of flat-panel detectors is according to its need in varying industries, and some of the industries that require the use of flat-panel detectors include 

Electrical component manufacturing uses the components produced to build other electrical/mechanical machines that ensure safety.

Flat-panel detectors are applied in conventional digital radiology and interventional digitized radiography, especially angiography. Flat-panel detectors are also applicable to mobile, or outdoor radiology exercises such as on the field to assess state maintenance works like welding. 

All these industries rely on good images during their respective quality control and quality assessment process. It is paramount for achieving accurate identification, analysis, and reporting of the actual quality of the inspected components.



To wrap up, we have duly expounded on flat-panel detectors as classified into two types: direct conversion, which converts x-rays to charge, and indirect conversion, which converts x-rays into lights and then to charge. It is also crucial to identify that indirect conversion can be discovered by employing charge-coupled instruments. They are small tools that entail optical coupling.

A flat-panel detector’s effective reach is also greater than X-ray Image intensifiers, and its visibility is in real-time when compared to image plates (IP).

And lastly, it is applicable for interventional and conventional digital radiology which are important considerations for you if you are in the market for a flat-panel detector.

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