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What is the difference between rod and cone vision? What type of vision is each? Which visual acuity is greater?
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What is the Fluoroscopic mA range?
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Fluroscopy Week 1
Fluoroscopy Visual Physiology
| Question | Answer |
|---|---|
| What is the difference between rod and cone vision? What type of vision is each? Which visual acuity is greater? | Cone vision is photopic vision and has high visual acuity by 10x with great contrast perception with the ability to see brightness. Rod vision is scotopic vision that sees grays, or night vision, but cannot perceive the differences between the grays. |
| What is the Fluoroscopic mA range? | 0.5 mA to 5.0 mA |
| What type of examination is fluroscopy? What does that mean? What is the purpose of contrast? | A dynamic study. Viewing internal structures in motion. To distinguish between adjacent structures. |
| The fluoroscope was invented by whom and when? | Thomas A. Edison in 1896 |
| What is photopic vision? What light receptors are used for photopic vision? Why is this? | Daylight vision, or bright vision. Cones. Because cones have high visual acuity, or contrast perception. |
| Where are the cones concentrated in the retina? What is this area called? | Cones are concentrated in the center of the retina. Fovea Centralis. |
| What is visual acuity? What light receptors have high visual acuity? How much greater is the acuity in comparison to the other light receptor? | The ability to perceive fine detail. The rods have 10x the visual acuity in comparison to cones. |
| What is scotopic vision? What light receptors are used for scotopic vision? Where are the rods concentrated in the retina? | Night vision or dim vision. The rods. Rods are concentrated in the periphery of the retina. |
| Why are dim objects viewed more readily when they are not looked at directly and are looked at peripherally? | Because the rods are concentrated in the periphery of the retina and the rods are used for viewing dim objects. |
| Why is image brightness intensified for fluoroscopy? | To utilize cone vision which has much greater visual acuity than rod vision. |
| What is the length of time the human visual system can acquire information? What happens if the visual system doesn't acquire enough information in this time? | 0.2 seconds. The visual system will reset itself and reacquire the information for the next 0.2 seconds. |
| What do the following do, Cornea, Iris, Lens? Where is the Iris located? | Cornea is the protective covering. The Iris in between the Cornea & Lens. Iris controls the amount of light admitted to the eye onto the Lens. Lens focuses light onto the Retina. |
| What type of light do the Rods and Cones detect? Where are the Rods and Cones concentrated and how many? | Rods detect dark light and the Cones detect bright light. 120,000,000 Rods are located on periphery of Retina and perceive dark vision. 7,000,000 Cones are concentrated at the center of Retina in the Fovea Centralis. |
| What type of vision is better at detecting changes in brightness levels? | Cone vision. |
| Why is the room dimmed when viewing the fluoroscopy screen by the radiologist? | Excessive light in the room decreases the ability of the light to resolve detail on the screen. |
| What may be a consequence of having the room too bright when viewing the fluoroscopy screen? Why is this? | The technical factors may be increased to make up for the lack of ability to resolve detail due to bright lights. The patient may receive an increased radiation dose. |
Created by:
jamestkelley
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