Imaging Equipment
What is the purpose of the step-down transformer? (Johnston, James N., and Terri L. Fauber. Essentials of Radiographic Physics and Imaging. Elsevier, 2020. Pg. 49)
It increases the current by reducing the voltage that has been applied to the filament
Is CCD a type of direct capture or indirect capture? (Pg. 115)
Indirect capture
What is Modulation Transfer Function (MTF) (Pg. 110)
It is a measure of a imaging systems ability to accurately display small anatomic objects having high spacial frequency
What provides a numeric value that indicates the level of radiation that was recieved by the digital image receptor? (Pg. 110)
Exposure Indicator
What is the primary factor that influences contrast in digital systems? (Pg. 122)
The look-up table
Low voltage, high frequency is passed through and converted to high-voltage AC
What does a CCD do? What does a x-ray scintillator do? (Pg. 115)
A CCD converts light into electronic signals which are sent to the computer work station. An x-ray scintillator converts X-rays into light.
What effect does increasing the Signal-to-noise ratio have on the image quality? (Pg. 107)
Increasing the SNR will improve the image quality
What happens when distance is created between the area of interest and the image receptor? (Pg. 139)
The diverging exit beam records the anatomic part with increased size distortion or magnification
What is the relationship between FOV and pixel size? Matrix size and pixel size? (Pg. 102)
FOV and pixel size share a direct relationship. Matrix size and pixel size share an inverse relationship.
What is the function of the automatic brightness control (ABC) in fluoroscopy? (Pg. 219)
It maintains the overall appearance of the intensified image by automatically adjusting the kVp, mA, or both.
What does CMOS stand for? What material is it made of? (Pg. 116)
Complementary metal oxide semiconductor. Crystalline silicon matrix.
In digital radiography, what will DELs do when light is absorbed by photodetectors? (Pg. 119)
DELs will collect the converted light into analog electronic signal and will then be digitized by an ADC.
What can artifacts due to make an image repeatable? (Pg. 109)
They can obscure important anatomy, a pathologic condition or patient identification information.
What are postprocessing functions? What does it allow the radiographer to do? (Pg. 120)
Postprocessing functions are computer software operations that allow manual manipulation of the displayed image.
Where is the vidicon tube connected to and what does it consist of? (Pg. 222)
The vidicon tube is connected to the output phosphor of the image intensifier by a fiberoptic bundle or an optic lens system. It consists of a diode tube contained in a glass envelope to maintain a vacuum.
What is the effect of contrast in regards to beam restriction and a smaller field size? (Pg. 145)
The decreased amount of scatter reaching the IR results in higher radiographic contrast, but requires an increase in mAs.
The range of exposures is very wide with digital receptors which we call dynamic range. What do we call the response to this wide exposure? (Pg. 120)
Linear
How is the level of radiographic contrast desired in an image determined? (Pg. 100)
It is determined by the composition of the anatomic tissue to be radiographed and the amount of information needed in order to create an accurate diagnosis
What can the values of region of interest help with? (Pg. 120)
They can help characterize disease
What are the advantages of using flat-panel detectors in place of an image intensifier in regards to the fluoroscopic tower? (Pg. 227)
Reduction in size, bulk, and weight of fluoroscopic tower, easier manipulation of tower, greater flexibility of movement, greater access to patient during examination
Name all the types of beam-restricting devices. What should they all be made up of? (Pg. 156-158)
Aperture diagram, cones and cylinders, collimators, automatic collimators. They should all be made out of a metal or a combination of metals that readily absorb x-rays
What is the relationship between spatial resolution and Nyquist frequency? (Pg. 122)
Spatial resolution is equal to one-half the Nyquist frequency
What is Quantum noise dependent on? (Pg. 107)
It is photon-dependent
What is the a priori model of histogram analysis? (Pg. 118)
It is a histogram analysis error when at least three edges in a collimated field are not identified. This results in all data, raw exposure or scatter outside the field is included in the histogram, which causes the histogram analysis error.