FLOUROSCOPIC EQUIPMENT AND MANY MORE OF IT

discussion

1. FLOUROSCOPIC EQUIPMENT BY Hassan J.M RAD 412

2. INTRODUCTION Fluoroscopy is a form of x-ray imaging that acquires images continuously and are displayed immediately on a monitor. It is used as a tool to guide and monitor diagnostic and therapeutic procedures in the visualization of internal structures of the body These include barium studies (swallow, meal, follow through and enema), catheter insertion and manipulation, stent placement, angiograms etc .

3. FLOUROSCOPY EQUIPMENT F luoroscopy provides a dynamic view of the anatomy, in real time within high temporal resolution and keeping total patient dose low. Real time always consider 30 frame/Sec Newer Fluoroscopy allow the acquisition of real time digital sequence of images (Digital Video), that can be played back Main components of a flouroscopy equipment are; X-ray tube, patient table, image detector and the monitor (digital imaging system) The equipment can either be fixed or mobile(C-arm).

4. fig.1 flouroscopy image acquisition

5. TYPES OF FLOUROSCOPY EQUIPMENTS X-ray image intensifier Flat panel detectors

6. X-ray Image Intensifiers Invention in 1950 allowed the image on the screen to be visible under normal lighting conditions, as well as providing the option of recording the images with a conventional camera. Improvements included the coupling of, at first, video cameras and, later, digital cameras. Available with input diameters of up to 45 cm, and a resolution of approximately 2-3 line pairs mm−1. The function of the x-ray image intensifier in the fluoroscopic imaging system is to convert the x-ray spectrum transmitted through the patient into a highly visible image. I mage intensifier exposure rate is typically set to 30 μR/sec for the 25-cm mode, 60 μR/sec for the 17-cm mode, and 120 μR/sec for the 12-cm mode

7. fig 2: outline of a flouro machine

8. fig3 : mode of operation of image intensifier

9. fig 4: magnification mode

10. Flat-panel detectors Flat panel detectors are a type of solid-state x-ray digital radiography It replac es the image intensifier in fluoroscope design because they offer increased sensitivity to X-rays, and reduc tion of patient radiation dose. Temporal resolution is also improved over image intensifiers, reducing motion blurring. Image intensifier operating in 'magnification' mode may be slightly better than a flat panel. Flat panel detectors are considerably more expensive to purchase and repair than image intensifiers primarily used in specialties that require high-speed imaging e.g., vascular imaging and cardiac catheterization.

11. TYPES OF FLAT PANEL DETECTORS There are two main types of flat panel detectors: D irect detectors I ndirect detectors. Direct detectors convert X-rays directly to charge using a photoconductor, such as amorphous selenium, which captures and converts X-ray photons directly into electric charge. I ndirect detectors use a scintillator material, such as cesium iodide (CsI), to convert X-rays into visible light, which is then detected by an array of photodiodes

12. The functional unit of a flat panel detector is composed of pixel arrays that convert X-ray radiations to light energy, which make up the images These pixel arrays are the sensitive parts of the flat panel detector and can include thousands of pixels with each pixel having square shapes and micrometer-long sides. For every functional unit of the flat panel detector, a very short radiation falls on the pixel array whenever an X-ray image is taken while the pixels collect and store this radiation until it is read out T hese pixels each include a photodiode that uses the impacting X-rays to generate an electrical charge. The pixels also include a switch which has a Thin-film Transistor (TFT) or Indium Gallium Zinc Oxide (IGZO) which are often utilized as a display technology.

13. fig. 5: flat panel detectors

14. Direct Detectors The type of X-ray conversion used is the direct conversion method conversion is done using photoconductors like amorphous selenium or similar photoconductors to directly convert incident X-ray energies to an electric charge. Electron hole pairs are generated from the X-ray photons incident on the selenium layer using an internal photoelectric effect. By applying a bias voltage to the selenium layer depth, the holes and electrons can be drawn to corresponding electrodes to generate a proportionate electric current to the radiation’s intensity. To readout the signals a general TFT array like a readout electronic device is employed.

15. Indirect Detectors Indirect detectors employ a scintillating material layer such as gadolinium oxysulfide or cesium iodide It convert s the X-ray energy to light with an amorphous silicon detector array embedded behind the scintillating layer. Similar to the image sensor chips found in a digital camera, photodiodes are included in every pixel that produces the electrical signals. These signals are comparable to the scintillator layer lights in front of the pixels which are used to generate a precise image of the X-ray image.

16. fig.6 direct and indirect conversion in fpd

17. fig.7 C arm flouroscopy machine

18. CONCLUSION fFlouroscopy equipment are an essentaial part of radiology investigation