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Rad 177 U3
flashcards
| Question | Answer |
|---|---|
| What are the three steps when using a diagnostic Imaging system? | image acquisition, image processing, and image display |
| What are the three steps on the pathway to processing a digital radiographic image? | preprocessing, processing, and postprocessing |
| Which postprocessing function eliminates black and white pixels that contribute little diagnostic information, and expands the remaining image data to ensure use of the full dynamic range? | Histogram Equalization |
| Which two image qualities can be adjusted with windowing? | Brightness, and contrast |
| In diagnostic digital imaging, which three things must we be able to distinguish from anatomic structures? | Other structures, Abnormal pathology, and unwanted or unintended structures. |
| Which image analysis factor describes how accurate the anatomic structures are recorded? | Geometric quality factors |
| What are the 4 factors which effect image quality? | receptor exposure, contrast, resolution, distortion |
| Which Image quality factor can be described as the amount of radiation the image receptor receives? | Receptor exposure |
| Which of the following is not a influencing factor for receptor exposure? a. Distance b. Beam intensity c. Bit Depth d. Tissue Thickness | c. Bit Depth |
| Which exposure factor is the most difficult factor to evaluate? | contrast |
| What is main factor controlling contrast? | kVp |
| True or false: Contrast is effected by the focal spot size. | False |
| How does beam restriction increase contrast? | By reducing scatter |
| True or false: Parallel grids reduce contrast. | True |
| which of the following are factors which effect image resolution? a. Patient motion b. Focal spot size c. kVp d. All the above e. both a and b | e. both a and b |
| What is the greatest deterrent to image resolution? | patient motion |
| what are the two types of distortion | size and shape |
| which of the following is not a factor of distortion? a. distance b. part alignment c. tissue density d. OID | c. tissue density |
| True or false; its best to decrease SID, and increase OID to minimize size distortion? | False |
| During a trauma AP tib/fib projection, the patient couldn't get their lower leg positioned perfect, and there is about a 10 inch gap between the IR and the lower leg. the SID is 72''. What is the MF factor? | 1.16 |
| If a patient's tibia measures 17.4 inches according to their x-ray, and you know the magnification factor is 1.16, approximately how long is the patients tibia? | 15 inches |
| Which type of distortion is primarily caused by tube angulation? | Shape distortion |
| True or false; the least amount of shape distortion is towards the edges of the anatomy and the IR? | False |
| What is the range of exposure an IR can detect? | Dynamic range |
| what is the primary factor that controls brightness? | predetermined computer algorithms |
| What unit is used to measure image sharpness? | Microns |
| what is the best monitor resolution typically used to view mammograms? | 5k mega pixels |
| What are the 6 digital image quality factors? | brightness, contrast, resolution, distortion, noise, exposure index |
| True of False; quantum noise looks foggy, and not grainy on the image? | False |
| True or false; the "S" type of exposure indicator is inversely proportional to intensity, while EI is Directly proportional to intensity. | True |
| What 4 factors effect the exposure indicator | mAs, kV, Total IR area irradiated, type of objects exposed |
| What is the main limitation of post-processing? | Post-processing cannot improve low signal-to-noise ratio |
| Window leveling adjusts (a.)__ while window width adjusts (b.)__ | a. brightness, b. contrast |
| What are the two types of human vision? | Scotopic, photopic |
| True or false; scotopic vision uses rods to view dim-light | True |
| What is the basic fundamental unit of photometry (measuring light) that measures intensity? | Lumen (lm) |
| What is the basic unit used to measure light intensity emitted from a single square foot of illuminated surface? | Illuminance (fc for English system of measurements, lx for SI) |
| True or false; a monitor's luminous intensity and contrast are reduced? | True |
| Which of the following types of monitors are no longer used in radiology? a. liquid crystal display (LCD) b. Cathode ray tube (CRT) c. light-emitting diode display (LED) d. both b and c | b. CRT |
| What are the three types of luminescence? | Fluorescence, Phosphorescence, and electroluminescent |
| An LED emits light when___. | electrically stimulated |
| What is the principal disadvantage of an LCD? | The angular dependence of viewing (the need to view the monitor from a perpendicular angle) |
| true or false; postprocessing happens automatically, and need no intervention from the radiologist or rad tech. | False |
| What is the purpose of subtraction in digital imaging? | To enhance contrast |
Created by:
cornie4953