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RADT456 Img Acq & Ev
ARRT registry review covering Image Acquisition and Evaluation
| Question | Answer |
|---|---|
| What are the factors that affect recorded detail (Resolution)? | OID, SID, Focal Spot Size, Patient factors, intensifying screens, and motion (pg. 298) |
| Term referring to misrepresentation of the actual size or shape of the structures imaged | Distortion (pg. 299) |
| Term that describes how closely fine details may be associated and still be recognized as separate details. | Resolution (pg. 299) |
| Term that refers to how well recorded detail can be seen | Visibility (pg. 299) |
| Two types of shape distortion | Foreshortening and Elongation (pg. 299) |
| Best method of minimizing voluntary motion | Good communication and suspended respiration (pg. 309) |
| Best method of minimizing involuntary motion | Short exposure time (pg. 309) |
| Intensifying screen speed increases as... | phosphor size increases, active/phosphor layer thickness increases, phosphor sensitivity increases, screen reflectance increases, recorded detail decreases (pg. 312) |
| Phosphors with a _____ atomic number react to x-ray photons more efficiently and possess greater speed. | High (pg. 312) |
| Defined as the overall amount of blackening on a radiographic image | Density (pg. 314) |
| Law that states "any combination of mA and exposure time that will produce a particular mAs, will produce identical image density." | Reciprocity Law (pg. 317) |
| The single most important factor associated with image density | mAs (pg. 317) |
| Minimum change in mAs to notice a recognizable change in density | 30% (pg. 317) |
| Equation for inverse square law | I1/I2 = D2^2/D1^2 (pg. 319) |
| Density maintenance formula | mAs1/mAs2 = D1^2/D2^2 (pg. 319) |
| Screen speed and image density are ________ proportional. | Directly (pg. 321) |
| Device used to absorb unwanted scatter radiation before it reaches the IR | Grid (pg. 323) |
| Grids are recommended for body parts ________ | 10 cm and greater (pg. 323) |
| Contributing factors to scatter radiation production | Larger x-ray field size (reduce by collimating), higher kV (correct by using optimum kVp), and thicker/denser body tissues (correct by using compression) (pg. 324) |
| Unwanted absorption of the useful x-ray beam with resulting loss of density across the image | Grid cutoff (pg. 324) |
| Types of grid use errors that contribute to grid cutoff. | Angling against grid lines, off level errors, off-focus errors, off center errors, and upside-down grid. (pg. 325) |
| Height of the lead strips in a grid compared with the distance between them | Grid ratio (pg. 326) |
| Number of lead strips per inch in a grid is termed as | Grid frequency (pg. 326) |
| Material for interspaces within a grid | Plastic, fiber, or aluminum (pg. 327) |
| Grid conversion factors | No grid - 1 5:1 grid - 2 6:1 grid - 3 8:1 grid - 4 10:1 or 12:1 - 5 16:1 - 6 (pg. 327) |
| Air gap technique of 6 inches provides similar results to a _______ grid, while a 10 inch air gap produces an effect that is equivalent to a _______ grid.. | 8:1, 16:1 (pg. 329) |
| How much filtration is required for radiographic tubes operated above 70 kVp? | 2.5 mm Al equivalent (pg. 330) |
| Purpose of filtration | To remove diagnostically useless x-ray photons that contribute only to patient dose (increases overall average energy of x-ray beam) (pg. 330) |
| Formula for total filtration | Inherent x added = total filtration (pg. 330) |
| Compensating filters are used for... | anatomic parts with very different thickness/absorption properties, and to balance the differences in these densities. (pg. 330) |
| Pathologic conditions that would require an increase in technique to produce a diagnostic image. | Ascites, rheumatoid arthritis, Paget disease, pneumonia, atelectasis, congestive heart failure, and edematous tissue (pg. 333) |
| Pathologic conditions that would require a decrease in technique to produce a diagnostic image. | Osteoporosis, osteomalacia, pneumoperitoneum, emphysema, degenerative arthritis, atrophic and necrotic conditions (pg. 333) |
| True or False: Beam restriction (collimation) reduces production of scattered radiation and, consequently, decreases image density. | True (pg. 336) |
| To use the anode-heel effect properly, the larger/thicker body part needs to be positioned on the ________ side. | Cathode (pg. 336) |
| True or False: In traditional (chemical) film processing, even small temperature changes of 2-3 degrees can cause a significant change in image density. | True (pg. 336) |
| When an image only contains a few number of densities, the image is considered to be of what scale? | Short scale or high contrast (pg. 339) |
| When there are many shades of densities with only slight differences between them on an image, this image is said to be... | Long scale or low contrast (pg. 339) |
| Subject contrast is a result of ________ ________. | Differential absorption (pg. 339) |
| What type of image contrast does low kVp create? | High contrast/short scale contrast (pg. 340) |
| What type of image contrast does high kVp create? | Low or long scale contrast (pg. 340) |
| Function of the contrast scale | Make image details visible (pg. 340) |
| Factors used to control the production of scattered radiation and improve contrast | Collimation, Optimum kVp, and thickness/density of tissues (compression). (pg. 344) |
| Without the use of a grid, scattered radiation can contribute to ___________ of the total image exposure. | 50-90% (pg. 347) |
| As grid ratio increases..... | Scattered radiation cleanup increases and contrast improves, contrast scale decreases (higher contrast results), exposure factors must increase, patient dose increases, and positioning latitude decreases. (pg. 347) |
| Two types of AECs | Ionization chamber and phototimer. (pg. 350) |
| Proper functioning of AEC is dependent upon... | Accurate positioning of body part of interest over selected photocell(s). (pg. 352) |
| True or false: Digital imaging has better spatial resolution than traditional film based imaging. | False. Film based imaging has an approximate spatial resolution of 10 lp/mm, while CR/DR ranges between 2.5 and 5 lp/mm. (pg. 354) |
| Related to the number of shades of gray within an image and is measured in bits | Dynamic range (pg. 355) |
| As matrix size increases (for a fixed field of view), pixel size is _______ and image resolution _______. | Smaller, increases (pg. 355) |
| Described as how much of the patient is included in the image matrix. | Field Of View (FOV). (pg. 356) |
| Type of signal to noise ratio that is desired for a diagnostic image. | High SNR (pg. 356) |
| Ability of an image receptor material to perceive and interact with x-ray photons. | Detective Quantum Efficiency (DQE). (pg. 356) |
| Materials used for CR/DR PSP receptor screens | cesium iodide, barium fluorohalide, and amorphous selenium. (pg. 356) |
| List the layers of a PSP in order | Protective layer, needle-shaped phosphor layer, reflective backing, polyester base support, antistatic layer, and lead foil backing (pg. 358) |
| The latent image can remain on a PSP for up to ______ hours before image fading is noticeable. | Eight (pg. 359) |
| If an IP and its storage plate has been unused for _________ hours, the PSP plate should be erased before use. | 48. (pg. 359) |
| Which step does a direct capture DR system eliminate in image production? | Scintillator step (pg. 364) |
| Smaller detector element size within a thin film transistor, the ________ the spatial resolution. | Better (pg. 364) |
| A computer system that serves to track patient information (Admission/discharge, diagnostic treatment services, pharmaceutical and equipment information/ billing information, and employee information. | Hospital Information System (HIS). (pg. 366) |
| Computer system that allows procedure ordering/scheduling, patient database maintenance, reporting and transcription, and billing within the radiology department. | Radiology Information System (RIS). (pg. 366) |
| The most common result of improper film storage. | Fog (pg. 381) |
| Unexposed film should be stored below what temperature? | Below 70 degrees F. (pg. 381) |
| Atmospheric humidity for film storage should be ... | between 40 and 60%. (pg. 381) |
| Tool/test used to test screen-film contact. | Wire mesh test (pg. 383) |
| Three classifications for image artifacts. | Handling, Processing, and Exposure. (pg. 383) |
| Information required on each x-ray image in order to be considered as legitimate legal evidence. | Patient name/identification number, side marker (right or left), examination date, and institution's name. (pg. 384) |
| Type of grain or crystal suspended within gelatin of film emulsion. | Silver bromide (halide) crystals. (pg. 385) |
| Purpose of developer solution in chemical film processing. | Converts latent image into the manifest silver image by reducing the exposed silver bromide grains to black metallic silver. (pg. 385) |
| Purpose of activator solution in chemical film processing. | Swells gelatin emulsion, enabling the reducing agents to penetrate the emulsion and reach the exposed silver bromide grains. (pg. 385) |
| Purpose of preservative solution in chemical film processing. | Prevents rapid oxidation to developer. (pg. 385) |
| Purpose of restrainer solution in chemical film processing. | Restricts developer activity to only react with exposed silver grains (controls fog). (pg. 386) |
| Purpose of fixer solution in chemical film processing. | Clears the film of unexposed, undeveloped silver bromide grains. (pg. 386) |
| Purpose of the "wash" process within chemical film processing. | Clears film of residual chemicals and is important for archival quality. (pg. 386) |
| Purpose of the hardener solution in chemical film processing. | Re-hardens gelatin emulsion to protect film from abrasions. (pg. 386) |
| Racks within a processor that are out of solution and bridge the gaps between the sections of the transport system. | Crossover racks. (pg. 387) |
| Located at the bottom of deep racks and serve to change the film direction as it changes from downward to upward motion. | Turnaround Racks. (pg. 387) |
| Temperature range that is maintained within a chemical processor. | 92-95 degrees farenheit (pg. 387) |
| Two methods of silver recovery. | Metallic displacement cartridges and electrolytic silver recovery. (pg. 388 & 389) |
| Three cycles a PSP undergoes | X-ray exposure, reading, and erasure. (Pg. 393) |
| A graphic representation of pixel value distribution | Histogram (Pg. 394) |
| Factors that affect a historgram analysis | Positioning accuracy, correct collimation, correct algorithm, delay in processing, changes in scatter radiation, SID, and OID. (Pg. 395) |
| A change in window width changes... | the number of gray shades (Pg. 396) |
| A change in the window level changes... | image brightness (Pg. 396) |
| The acronym PACS stands for... | Picture Archiving and Communications System (Pg. 396) |
| Factors that can create distortion | Patient motion, excessive OID, insufficient SID, inappropriate screen/film combination, too large of focal spot. (Pg. 405) |
| Shape distortion is a result of ... | improper alignment of x-ray tube, body part, and image receptor (Pg. 405) |
| Uses for slower screen speeds (i.e. 100) | Small parts such as extremities (Pg. 407) |
| PSPs are sensitive to... | electromagnetic radiations such as ultra-violet and gamma, as well as particulate radiations such as alpha and beta particles. (Pg. 408) |
| Greatest enemy to image detail. | Patient motion (Pg. 413) |
| Solution that is recommended for cleaning PSPs. | Anhydrous ethanol (other materials can cause breakdown of the protective coat and create artifacts). (Pg. 423) |
Created by:
jksmith1
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