First, what is a detector? Operators use digital radiography detectors to obtain X-ray images in place of plain film or computed radiography systems. They also utilize detectors instead of image intensifier systems for fluoroscopy, interventional, and mobile x-ray systems. Different classes of digital radiography detectors vary based on the physics behind image acquisition, scintillator use, and the device's readout. Here, we'll discuss the two major classes of flat panel detectors, what makes them unique, and average costs.
What Are the Two Classes of Flat Panel Detectors?
At Maven Imaging, we break flat panel detectors into two categories: indirect flat panels and direct flat panels.
The most common flat panel detector is the indirect flat panel. Indirect flat panels use three main steps to obtain an image. First, the scintillator measures the x-ray signal by converting x-rays to visible light. Next, the Si Photodiode or Charge Coupled Device (CCD)/Complementary Metal-Oxide-Semiconductor (CMOS) converts visible light to charge. These electrons then transfer to a digital signal. The CCD/CMOS or Si photodiode and Thin Film Transistor (TFT) array measure the light photons.
Indirect flat panels are further broken down based on the charge category or readout used. This includes the TFT indirect flat panel or the CCD/CMOS indirect flat panel. The TFT type uses an array of photodiodes to convert light into an electrical signal read out by the TFT. Interestingly, this technology resembles Liquid Crystal Displays (LCDs) in flat panel monitors and TVs. The CCD/CMOS technology is similar to the technology used in digital cameras.
Direct flat panels work differently than indirect panels because they convert x-rays directly to electrons. A TFT then measures electrons, allowing direct flat panels to achieve higher spatial resolution by skipping the visible light step responsible for blurring images.
The cost for either indirect or direct flat panels depends on various factors, but it’s safe to say the price can range anywhere from $18k to $50k.
What Is the Average Cost for Each Flat Panel Detector Class?
Indirect flat panel detectors are less expensive than direct panel detectors overall. The two options for indirect flat panel detectors range in price based on the chosen scintillator. The most common scintillators are the GOS, made of Gd2O2S (Gadolinium OxiSulfate), or the CSI, made of Cesium Iodine. When selecting between a GOS or CSI scintillator, you'll notice a cost trade-off for spatial resolution.
The GOS has some benefits over the CSI; it's less expensive yet provides quality light output. However, the light may spread out more than in a GOS, which could result in a hazy light signal or output blurring.
The CsI system is more expensive than the GOS system, but this is due to the many benefits of the CsI. The CsI has a columnar light structure with less light spread, resulting in reduced blurring and higher spatial resolution.
Direct flat panel detectors are the most expensive systems due to their high resolution.
What Is the Advantage of Flat-Panel Detectors?
Each flat panel detector has its advantages that make it suitable for specific imaging needs and preferences. Let’s take a closer look at the benefits of each.
Advantages of Indirect Flat Panel Detector (TFT)
The advantages of the indirect flat panel detector with a TFT are the fast readout speed, relatively inexpensive cost, and low dose readout. These panels are best suited for fluoroscopy and angiography studies where imaging needs to be instantaneous and the radiation dose is lower. They are also an excellent choice for general radiography.
Advantages of Indirect Flat Panel Detector (CCD)
Indirect flat panel detectors with CCD are inexpensive but provide good resolution and readout speed - best for general radiography. In fluoroscopy, they are slightly less efficient than a TFT at producing a fast readout at low doses of fluoroscopy.
Advantages of the Direct Flat Panel Detector
The significant advantage of a direct flat panel detector is its drastically higher resolution. Direct flat panel detectors are best for high-resolution imaging needs with a soft beam, such as mammography studies.
Looking To Upgrade Your X-Ray Equipment? We Can Help.
If you're considering purchasing a new flat panel detector for your practice, Maven Imaging can happily guide you through this process. Either fill out a form directly on our website or give us a call to discuss your financing options. We have many opportunities to make purchasing a new flat panel detector seamless and effortless.