Scatter Control
What serves the purpose of limiting patient exposure AND reducing the amount of scatter radiation within the patient?
Beam Restriction
Cassetteless digital systems have fixed spatial resolution determined by?
Thin-Film Transistor (TFT) detector element size (DEL)
Very light sensitive & can respond to very low light intensities; can respond to a wide range of light intensities.
Charged Coupled Device (CCD)
A backup time for the AEC serves to ____?
Protect the patient from over exposure - or - protect the X-ray tube from excessive heat
The image intensifier's input phosphor generally is composed of ____?
Cesium Iodide
A radiograph made with a parallel grid demonstrates decreased receptor exposure on its lateral edges. This is MOST LIKELY due to?
Decreased SID
Resolution in CR increases as:
1. Laser beam size decreases
2. Monitor matrix size decreases
3. PSP crystal six decreases
1 and 3 only
Range of exposure intensities that an image receptor can respond to and use to acquire image data?
Dynamic Range
A technique chart should be prepared for each AEC x-ray unit and should contain which of the following information for each type of exam?
1. Photocell(s) used
2. Optimum kVp
3. Backup time
1, 2, and 3
What system functions to compensate for changing patient/part thickness during fluoroscopic procedures?
(ABC) Automatic Brightness Control
In radiography of a large abdomen, which of the following is (are) effective way(s) to minimize the amount of scattered radiation reaching the image receptor (IR)?
1. Use of optimal collimation
2. Use of low mAs
3. Use of a low-ratio rather than high-ratio grid
1 only
A higher DQE indicates a potentially ______ patient dose.
Lower
A measure of exposure in air, followed by computation to estimate absorbed dose to the patient
Dose-Area Product (DAP)
Name the two types of AEC systems
Phototimers & Ionization Chambers
Magnification fluoroscopy is only possible with?
Multifield Image Intensifiers
Disadvantages of moving grids over stationary grids include which of the following?
1. They can prohibit the use of very short exposure time
2. They increase patient radiation dose
3. They can cause phantom images when anatomic parts parallel their motion
1 and 2 only
The digital image has what type of response to x-ray exposure?
Linear
A software function to suppress image noise
Smoothing
Minimum response time
Is an expression of the ability of an image intensifier tube to convert x-ray energy into light energy and increase the brightness of the image in the process
Brightness Gain
What type of beam-restricting device provides the most flexibility in adjusting the x-ray field size?
Collimator
One problem with indirect-capture methods is that there is an extra step during which x-rays are converted to light and then to electrons, which causes _____?
Loss of resolution
available grayscale & refers to the number of shades of gray that can be displayed within a pixel
Bit Depth
Excessive or insufficient _______ may affect the amount of exposure reaching the image receptor.
collimation
What improves ability to see small structures, but it also increases patient dose?
Field of View (FOV)