Radiography now is transpiring a new beckon of innovation, digital, since 1895 when the German Physician, Wilhelm Rontgen, established that x-rays could pass through the tissues of human body to make bones and metals visible.
Digital radiography (DR) today is a budding revolution which is luring the global market stirringly by quickly swapping conventional radiography or even computed radiography (CR) systems with the help of flat panel detector (FPD), also known as x-ray detector or DR detector.
Digital Radiography Market
The global digital x-ray market is expected to reach $10.46 billion by 2020 from $6.15 billion in 2015 at CAGR of 11.2 percent. The market is dominated by North America followed by Europe, Asia and Rest of the World (RoW), according to MarketsandMarkets.
The major companies operating in this market are GE Healthcare UK), Philips Healthcare (Netherlands), Siemens Healthcare (Germany), Hitachi Medical Corporation (Japan), Toshiba Medical Systems Corporation (Japan) and Shimadzu Corporation (Japan), Hologic Inc. (USA), and Carestream Health (USA).
Besides there are also companies which offer DR retrofit solutions such as Thales Group (France), iRay Technology (China), Fujifilm Medical Systems (Japan), Konica Minolta (Japan), Canon Inc. (Japan), Vieworks (Korea), Agfa Healthcare (Belgium), PerkinElmer USA), and Varian Medical Systems (USA).
Flat Panel Detector (FPD)/DR Detector
DR is primarily based on panels called Flat Panel Detectors (FPDs) or DR Detector which upgrades your existing radiography or fluoroscopy system into complete digital solution in lower cost. It captures x-ray images and converts them into electronic data to display on computer in high resolution.
Advantages of FPD/DR Detector
It hence fosters radiographic workflow by providing quick image acquisition and display, superior image quality, lower radiation dose to patients, high image resolution accompanied by low sensitivity and low noise thereby easing clinicians to diagnose more conveniently and more distinctively.
Add-on feature of DR Detector is that the image could be shared with clinicians through PACS eliminating the cost of x-ray film and printer. Automatic Exposure Detection (AED) is another feature offered by some of the companies that can detect images without the need of cable connections between x-ray detector and x-ray generator.
There is an incessant contest among the said manufacturing companies from various countries to take control over the Digital Radiography (DR) market. China however is taking up the lead in the region due to decreased cost of purchasing FPDs with same features and specifications that of manufacturers in US or Europe.
DR Detector Types, Quality and Features
There is a layer of material inside every DR Detector called Scintillator and the two main chemical compounds used as Scintillator are Gadolinium Oxysulfide (Gadox/GOS) and Cesium Iodide (CsI).
The image quality of CsI panel is better than that of Gadox/GOS however it so feeble that only a professional can perceive this CsI advantage. However capturing an imaging with CsI requires lesser dose (10-30%) as compared to Gadox though it is not that hazardous though advantage is an advantage. The only area Gadox/GOS outshines is that it costs 20-30% less than the CsI though you have to compromise on extra dose and slight image quality.
Underlying better image quality and reduced patient dose, CsI panel is graded better than Gadox/GOS. Nonetheless Gadox panels are largely sold out throughout the world for being economical yet CSI panels are gradually breaking through as well. Nevertheless, both these chemical compounds are approved for use in diagnostic imaging and readily available in the marketplace.
Physical Parameters to DR Quality and Performance
Detective quantum efficiency (DQE) and Modulation Transfer Function (MTF) are two of the important checks to weigh the quality and performance of a digital radiography system or FPD.
Detective Quantum Efficiency (DQE) is the fundamental metric to evaluate the performance of digital radiography system related to image quality and the efficiency of a detector in converting incident x-ray energy into an image signal. It thus describes the ability to of an x-ray detector to produce high signal-to-noise ratio (SNR). High DQE means that less radiation dose is required to achieve similar image quality so with constant radiation exposure, increased DQE will improve image quality. (Source: Radiopedia)
You may also read the abstract “Detective quantum efficiency: a standard test to ensure optimal detector performance and low patient exposures” by Society of Photo-Optical Instrumentation Engineers (SPIE).
Modulation Transfer Function (MTF) is the spatial frequency response of an imaging system or a component. It is the contrast at a given spatial frequency relative to low frequencies. It is an important figure of merit of an imaging system that indicates its ability to capture, transfer, and display information about features with fine spatial detail.
On the radiogram, objects having different sizes and opacity are displayed with different gray-scale values. MTF is responsible for converting contrast values of different sized-objects into contrast intensity levels in the image (image contrast). For general imaging, the relevant details are in a range between 0 and 2 cycles/mm, which demands high MFT values.
In summary, MTF is the capacity of a detector to transfer the modulation of the input signal at a given spatial frequency to its output. MTF is a use full measure of a true or effective resolution, since it accounts for the amount of a blur and contrast over a range of spatial frequencies. (Source: Radiopedia)
DR slashes CR market by 25% in 2014
According to a report a IHS, market research and consulting firm, the market revenue of computed radiography (CR) market dipped by nearly 25% from 2013 to 2014. This major decline is primarily hit by the strong uptake of new flat panel digital (FPD) radiography.
It further forecasts that CR market in developed world is expected to decline continuously from 2015 to 2019 however it still has some demand in emerging markets such as parts of Latin America and Asia Pacific.