Fluoroscopy Final exam Question with 100% correct Answers 2024

Fluoroscopy Final exam Question with 100% correct Answers 2024 How is fluoroscopy used in angiography? To position the system for the recording of images of contrast material being injected via catheter How is fluoroscopy used in angioplasty? To provide imaging guidance for interventional procedures? Three types of fluoroscopy cameras analog vidicon, CCD or CMOS (Complementary metal-oxide semiconductor) "Real time" imaging frame rate 30 fps, about the same as old analog TVs Fluoroscopic imaging chain diagram Copper filtration is combined with (higher/lower) kVs for dose reduction in angiography lower When would you use an attenuator wedge in a fluoroscopic system? To reduce bright regions, such as those created in the pulmonary space between the heart and chest wall Dose difference per image between fluoroscopy and radiography fluoroscopy: 9-17 nGy (1-2 uR) per image radiography: 5-9 uGy (.6-1 mR) per image Four principle components of an II 1. vacuum housing to keep air out and allow unimpeded e- flow 2. an input layer that converts the absorbed incident x-rays into light, which in turn releases e3. an e- optics system that accelerates and focuses the e- emitted by the input layer onto an output layer 4. an output phosphor that concerts the accelerated e- into a visible light image II Diagram G1-3 are additional focusing electrodes II Input Screen Diagram The vacuum window of an II is typically made of what? ~1mm Al Why is the input surface of an II curved? To withstand the force of air pressing against it (contains vacuum). A 35 cm FOV can withstand a ton of atmospheric air pressure What is the support layer of the II Input Screen? Commonly 0.5 mm Al, supports the input phosphor and photo-cathode layers. The first component in the electronic lens system, its curvature designed for accurate e- focusing Most common material for II phosphor CsI, can be formed into columnar "light pipes." As a result, the phosphor can be quite thick and still produce high res. They are approx 400 um tall and 5 um wide and formed by vacuum deposition of CsI onto substrate. They contain a trace amount of Na, causing them to emit blue light. The K-edges of Cs (36 keV) and I (33 keV) are well positioned with respect to the fluoroscopic x-ray spectrum, which contribute to high x-ray absorption efficiency K-edge of cesium (CS) 36 keV K-edge of Iodine (I) 33 keV Photocathode of II A thin layer of antimony and alkali metals (such as Sb2S3) that emits e- when struck by visible light (10-20% conversion efficiency) Electronic gain of II When the kinetic energy of an e- is dramatically increased by acceleration due to a voltage difference between the anode and cathode When e- travel from the photocathode to the output phosphor of an II, they are (magnified/minified) and the light intensity (increases/decreases) minified, increases. The 15-35 cm diameter input image is focused onto a 2.5 cm (1") diameter circle (think magnifying glass) What causes pincushion distortion of a fluoro image? The curvature of the input screen What is the pentode electronic lens system of the II? G1, G2, G3 focusing electrodes, input phosphor substrate (Cathode) and anode just proximal to the output phosphor Typical voltage across an II 25,000 - 35,000 V Output phosphor of II Made of zinc cadmium sulfide doped with silver (ZnCdS: AG), which has a green emission spectrum. The phosphor particles are very small (1-2 um) and the phosphor