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Rods are a.more sensitive to light than cones b.less sensitive
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How is illumination measured?
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fluroscopy chpt 21
| Question | Answer |
|---|---|
| Rods are a.more sensitive to light than cones b.less sensitive | a. more sensitive |
| How is illumination measured? | lumen per square meters or lux |
| X-ray's and fluro are viewed under what illumination levels? | =100-1000 lux |
| Rods are a.more sensitive to light than conesb.less sensitive | =a. more sensitive |
| Structures in the eye used for daylight vision are:a.rods b.cones | =b.cones |
| Another term for night vision is? a.scotopic b.photopic | =a.scotopic |
| True or false: Rods are colorblind | =True |
| Another term for daylight vision is: a.scotopic b.photopic | =b.photopic |
| Structure better detecting different brightness levels are? | =cones |
| What is function of image intensifier tube? | =Receives x-ray beam and converts it into visible light image of high intensity. |
| X-Ray's enter the glass envelope on the image intensifier tube and interact with what first? | =Input phosphor |
| The input phosphor is made of what material? | =Cesium iodide |
| Once the xray beam interacts with input phosphor, what occurs next? | =X-ray then converted to visible light. |
| The photocathode is located where? | =Bonded directly to input phosphor |
| What is the photocathode made of?= | Cesium and antimony compounds |
| What is the function of the photocathode? | =Responds to stimulation of input phosphor light by the emission of electrons known as photoemission. |
| The number of electrons emitted is ________ to the intensity of the light that reaches it. | =Directly proportional. |
| Electrons produced by photoemission will be accelerated to where?= | To the anode. |
| What shape is the anode? | =A circular plate with a hole in it. |
| What is located on the other side of the anode? | =Output phosphor |
| What is the output phosphor made of? | =Zinc cadmium sulfide. |
| What is the job of the anode? | =To focus the electrons into a beam. |
| What is the job of the electrostatic focusing lenses? | =To control the path of the electrons. |
| What is the function of the output phosphor? | =The site where electrons interact and produce light. |
| What is the equation for Flux Gain | number of output light photons/number of input x-ray photons. |
| What is the the equation for Brightness Gain | Minification gain x flux gain |
| What is the equation for Minification gain | (di/do)2 di-diameter of input phosphor do-diameter of output phosphor |
| What happens as the diameter of the multified intensifiers is decreased | The image becomes more magnified. |
| What is the function of the TV camera? | Converts light from output phosphor into an electrical signal and sends to TV monitor. |
| Function of the glass envelope of TV camera? | maintains vacuum and provide mechanical support for internal components. |
| The cathode in the TV camera contains what? | The electron gun. |
| What is the electron gun? | A heated filament that supplies constant electron current by thermionic emission. |
| What forms the currents from electron gun into an electron beam and helps accelerate them? | Control grid. |
| The beam from the electron gun is further accelerated and focused by the? | Electrostatic grids |
| What are the three layers of the target assembly? | 1.face plate 2.signal plate 3.target/photoconductive |
| What is the normal tube current range during fluoroscopy? | 1-5ma |
| The image intensifier improved fluoroscopy by increasing image______? | brightness |
| Visual acuity int he is greatest at the ________, where ______ are concentrated? a. retinal periphery, cones b.fovea centralis, cones c.retinal periphery, rods d. fovea centralis, rods | b.fovea centralis, cones |
| The ____ in the retina are stimulated by ______ light: the ___ are stimulated by ________ light. a.rods, bright;cones, low b.rods, low;cones, low c.rods, low;cones, bright d. rods, bright; cones, bright | c.rods, low;cones, bright |
| X-rays that exit the patient and enter the image intensifier first interact with the a.output phosphor b.input phosphor c.photocathode d.anode | b.input phosphor |
| The output phosphor of the image intensifier is composed of a.cesium iodide b.antimony c.zinc cadmium sulfide d.graphite | a.cesium iodide |
| The input phosphor converts ______ to ______ a.xrays, electrons b.light, electrons c.electrons, light d.xrays, light | d.xrays, light |
| The ________ in the image intensifier emits electrons when it is stimulated by light a.input phosphor b.output phosphor c.photocathode d.electron gun | c.photocathode |
| The number of light photons emitted within the image intensifier is __________ to the amount of x-ray photons exiting the patient a.equal b.unrelated c.inversely proportional d.directly proportional | d.directly proportional |
| Electrons hit the ________________ after exiting the anode. a.output phosphor b.tube housing c.photocathode d.focusing lenses | a.output phosphor |
| The __________________________ is the product of the minification gain and the flux gain. a. horizontal resolution b. brightness gain c. contrast resolution d. flux gain | b.brightness gain |
| The ratio of x-rays incident on the input phosphor to light photons exiting the output phosphor is called a. magnification gain b. minification gain c. brightness gain d. flux gain | d.flux gain |
| An image intensifier tube is identified by the diameter of its a. input phosphor. b. glass housing. c. output phosphor. d. focusing lenses. | a.input phosphor |
| The capability of an image intensifier to increase the illumination level of the image is called its a. flux gain. b. conversion factor. c. brightness gain. d. veiling glare. | c.brightness gain |
| Viewing the fluoroscopic image in magnification mode increases a. contrast resolution. b. spatial resolution. c. patient dose. d. All of the above. | D.ALL OF THE ABOVE |
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mcabrio