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Technique and Errors
| Question | Answer |
|---|---|
| Exposure Latitude | the extent to which a light-sensitive material can be overexposed or underexposed and still achieve an acceptable result |
| Exposure Field Recognition | digital radiography process in which the computer distinguishes the raw data representative of info within the exposure field from that which comes from outside the exposure field so that proper automatic rescaling can occur |
| Exposure Index | a measure of radiation in the relevant image region on the receptor |
| Target Exposure Index | reference exposure obtained when an image is properly exposed |
| Deviation index | measures the difference between how many photons should be reaching the image receptor in the relative image region for that particular study and the amount of x-ray photons that actually do reach the image receptor in the relative image region |
| Data Drop | Extreme overexposure, however can detract from optimal image quality |
| Detector Saturation | Data drop that involves areas or regions of the detector |
| Diagnostic Acuity | Image quality on a radiograph and fall within a acceptance exposure index range |
| Diagnostic Efficacy | the fateful representation of the patient on a medical radiograph |
| Diagnostic Yield | the amount of clinically significant information produce |
| Electronic annotation | improve image diagnostic yield |
| Optimal kVp | The maximum kVp level that will produce images within appropriate that are contrast that are consistently within acceptance limits |
| Photon Starvation | Inadequate exposure to the detector elements |
| Electronic Masking | Cropping or shuttering. Used to remove undesirable information in an effort to improve image quality |
| Histogram Analysis Error | Image Processing and Display | Radiology Key If at least three edges are not identified, all data, including raw exposure or scatter outside the field, may be included in the histogram, resulting in a histogram analysis error |
| Moiré Effect | mechanical interference of light by superimposed networks of lines |
| Interpolation | a mathematical process used to smooth, enlarge or average images that are being displayed with more pixels than that for which they were originally reconstructed |
| Flatfielding | process of compensating for different gains and dark currents in a image detector |
| How should a digital exposure techniques system be established ? | According to the ASRT White Paper on best practice in digital radiography, it is recommended "to use exposure technique charts that are continuously improved and applicable to a wide range of patient sizes" (2012). |
| what are the two most common factors that affect digital | kVp my contrast |
| how does digital imaging latitude compare to that of film screen systems? | screen film has a much narrower latitude to get the correct exposure, so a small change in photon energy has a greater impact. Digital radiography has greater exposure latitude, so image is still acceptable with small changes in photon energy. |
| what does a DI value of -2 indicate? What is recommended action for such a value? | under exposure |
| What causes photon starvation? | Not enough exposure to the detector elements |
| How are data drop and detector saturation related? | data drop can lead to detector saturation |
| which technical factor controls the amount of scatter in digital imaging? | mAs |
| Should electronic masking be used to substitute for exposure collimation? | No |
| What can cause electronic artifacts on DR images? | Bucky Motor Interference, X ray to rotator initiation, AEC noise. Pg 324 |
| How is exposure field recognition utilized? | used to recognize the clinically useful area on the imaging plate so it is the only data that will be manipulated, and it eliminates the signals from outside the collimated field. |
| how should a technology select kilovoltage to minimize patient radiation dose? | increasing the kV reduces the exposure of the patient and especially to the skin exposed by the beam. |
| how many distinct margins should appear on digital radiography? | At least three collimated margins should be seen but four is better |
| What type of algorithm is used to correct for malfunctioning pixels? | interpolation algorithm |
| what are the three general classifications of digital image artifacts? | image receptor artifacts, software artifacts, and object artifacts |
| what type of error can occur when an image is not properly aligned with the image receptor? | technique error |
| What happens when the collimated X ray beam interact with a patient specific area shield? | Response time increases in an effort to penetrate the lead shield. |
| why is it important to select the proper exam protocol for each projection? | Because each exam has a certain histogram for that specific projection |
| what is the image wisely initiative? | a joint initiative of ACR, RSNA, ASRT and AAPM, provides information to the medical community to promote safety in medical imaging |
| What is the image gently initiative? | the goal of the Image Gently Alliance is to through advise, to improve safe and effective imaging care of children worldwide |
Created by:
arronstewart1