Mosby's Review: Chapter 4: Image Production (digital image acquisition)

magnification is caused by 1. short sid 2. long sid 3. short oid 4. long oid

1,4

Undesirable fluctuations in brightness are called: a. MTF b. Image noise c. Quantization d. Scintillation

b. Image noise

mathematical codes used to generate the digital image are called a. binary codes b. algorithms c. binary digits d. bytes

b. algorithms

the available grey scale of an imaging system is determined by a. pixel pitch b. bit depth c. exposure latitude d. image latitude

b. bit depth

The thicker part of anatomy should be placed under which aspect of the x-ray tube? a. central ray b. cathode c. anode d. collimator

b. cathode

the relationship between kvp and receptor exposure may be describes as a. directly proportional b. direct, although not proportional c. governed by the 15-50 rule d. controlled by xray tube current

b. direct, although not proportional

an indicator of the dose level needed to acquire an optimal image is a. detective quantum efficiency b. dose area product c. field of view d. dynamic range

b. dose area product

digital imaging is driven by a. kvp b. mas c. ir speed class d. exposure

d. exposure

The range of SIDs that may be used with a focused grid is called: a. grid ratio b. objective plane c. anticutoff distance d. grid radius

d. grid radius

which of the following is a graphical representation of pixel values a. dynamic range b. luminance c. look up table d. histogram

d. histogram

As speed class increases: a. The likelihood of noise increases b. The likelihood of noise decreases c. Patient exposure increases d. Sharpness increases

a. The likelihood of noise increases

a software function that evens the brightness displayed in the image is called a. smoothing b. equalization c. postprocessing d. subtraction

a. smoothing

the useful image acquisition area of an image receptor is a. detector element b. detector size c. tft size d. dynamic range

b. detector size

receptor exposure may be defined as a. amount of remnant radiation striking the image receptor b. dose area product c. dqe d. differences in dark areas on the radiographic image

b. dose area product

an artificial increase in display contrast at an edge of the image is a. smoothing b. edge enhancement c. contrast resolution d. spatial resolution

b. edge enhancement

quality assurance and maintenance of cr cassettes including erasing plates at least a. daily b. every 48 hours c. every 3 months d. weekly

b. every 48 hours

The best scatter cleanup is achieved with the use of: a. Air gap technique b. Focused grids c. Crosshatch grids d. Parallel grids

c. Crosshatch grids

Distortion that occurs when the x-ray beam is angled against the long axis of a part is a. elongation b. magnification c. minification d. foreshortening

d. foreshortening

spatial resolution is a. photographic representation of the part being radiographed b. controlled by kvp c. controlled by mas d. geometric representation of the part being radiographed

d. geometric representation of the part being radiographed

grid frequency is defined as a. the same as grid ratio b. the amount of lead in the grid (expressed in terms of focusing distance) c. how often a grid is used d. the amount of lead in the grid (expressed as the number of lead strips per inch)

d. the amount of lead in the grid (expressed as the number of lead strips per inch)

mas directly controls a. the nergy of xray emission spectrum b. the quality and quantity of xrays produced at the cathode c. the quality and quantity of xrays produced at the anode d. the quantity of xrays produced at the anode

d. the quantity of xrays produced at the anode

the variation of xray intensity along the longitudinal axis of the xray beam describes a. beam collimation b. positive beam limitation c. anode heel effect d. xray emission spectrum

c. anode heel effect

visible differences in adjacent structures on a radiographic image describe a. receptor exposure b. spatial resolution c. signal loss d. contrast resolution

d. contrast resolution

digital system operate at what speed class a. 200 b. 400 c. 100 d. the speed class is chosen by the radiographer

d. the speed class is chosen by the radiographer

A grid with lead strips and aluminum interspaces that are angled to coincide with the divergence of the x-ray beam is called a. parallel grid b. focused grid c. crosshatch grid d. rhombic grid

b. focused grid

choose all that describe the outcome of using low kvp (choose 3) a. high contrast b. few gray tones c. long scale contrast d. short scale contrast e. low contrast f. many gray tones

a,b,d

choose all that will result in higher spatial resolution (choose 3) a. long sid b. long oid c. short sid d. short oid e. large focal spot f. small focal spot

a,d,f

The smallest area represented in a digital image is the: a. Image matrix b. Pixel c. Voxel d. Bit

b. Pixel

More uniform penetration of anatomic structures occurs when what level of kVp is used? a. low b. high c. kvp does not affect penetration d. level at which photoelectric interaction predominates

b. high

Improper use of grids may result in an image artifact known as: a. snr b. moire pattern c. elongation d. foreshortening

b. moire pattern

choose all that describe the outcome of using high kvp (choose 3) a. high contrast b. few gray tones c. long scale contrast d. short scale contrast e. low contrast f. many gray tones

c,e,f

Smoothing software may result in: a. Enhanced fine detail b. Less distortion c. Loss of fine detail d. Increased distortion

c. Loss of fine detail

Lower spatial resolution may be caused by which of the following factors? A. Short OID B. Long SID C. Small focal spot D. Wide pixel pitch

D. Wide pixel pitch

Grid cutoff may be described as: a. Decreased density in the middle of the radiograph caused by the use of a parallel grid inserted upside down b. Decreased density on a radiograph as a result of absorption of image-forming rays c. Increased density in the center of a radiograph caused by the use of a focused grid inserted upside down d. Decreased density on the edges of a radiograph only

b. Decreased density on a radiograph as a result of absorption of image-forming rays

a radiographic image with few gray tones,primarily exhibiting black and white, would be described as have what type of contrast 1. long scale 2. short scale 3. low 4. high

2,4

what allows more anatomical structures to be captured during an exposure a. contrast resolution b. spatial resolution c. dynamic range d. mtf

c. dynamic range

to reduce patient dose, exposure technique in digital imaging should be adjusted by a. lowering kvp b. increasing mas c. shortening sid d. increasing kvp

d. increasing kvp

the primary controlling factor of contrast is a. mas, which control the energy of the xrays produced b. kvp, which primarily controls the quantity and quality of xrays produced c. focal spot size, which controls the quantity and quality of xrays produced d. kvp and bit depth

d. kvp and bit depth

the function of contrast is to a. make the image appear sharper b. compensate for uneven anatomic structures c. brighten the image d. make detail visible

d. make detail visible

Bit depth is equal to: A. 2^n (n equals the number of bits) B. 4096 shades of gray C. Pixel pitch D. Bits times bytes

A. 2^n (n equals the number of bits)

Excessive processing of the digital image may: A. Degrade visibility of anatomy B. Provide additional anatomic information C. Enhance visibility of desired anatomy D. Increase patient dose

A. Degrade visibility of anatomy

The CR reader unit scans the IP with a(n): A. Infrared light B. Laser C. Sonar D. Visible white light

B. Laser

the number of pixels/mm in an image is called a. pixel density b. bit depth c. pixel pitch d. matrix depth

a. pixel density

the process of assigning a value to each pixel to represent a gray tone is called a. quantization b. scintillating c. nyquist frequency d. sampling

a. quantization

Use of the air gap technique: A. Works because x-rays are absorbed in the air between the patient and the film B. Should occur when possible C. May cause some magnification because of decreased OID D. Works because scatter radiation travels in divergent paths and misses the IR as a result of increased OID

D. Works because scatter radiation travels in divergent paths and misses the IR as a result of increased OID

choose all of the following statements that are accurate pertaining to the role of kvp in radiographic image production (choose 3) a. as kvp increased, penetrating ability of the xrays increases b. as kvp increased, more xrays exit the patient to strike the image receptor c. as kvp is decreased, wavelength decreases d. as kvp increases, receptor exposure increases e. as kvp decreases, receptor exposure remains constant because mas controls receptor exposure

a,b,d

choose all that are true concerning grids (choose 3) a. contrast improvement factor is the measure of the ability of a grid to enhance contrast b. grid selectivity is the ratio of primary radiation transmitted through the grid to secondary radiation transmitted through the grid c. grids are used when part thickness is less than 10 cm d. gcf is the amount of increase in kvp necessary when converting from nongrid to grid technique e. the main function of grids is radiation protection f. the main function of grids is to prevent compton scatter from reaching the ir g. grids prevent the production of scatter

a,b,f

When a nongrid technique using 10 mAs and 75 kVp is changed to a 12:1 grid using 75 kVp, what new mAs must be used to create the same image? a. 50 mas b. 2 mas c. 40 mas d. 120 mas

a. 50 mas

distortion that occurs when the x-ray beam is angled along the long axis of a part is a. elongation b. magnification c. minification d. misrepresentation

a. elongation

the radiographic image is formed by a. exit rays striking the IR b. laser light c. cosmic rays d. electrons and heat

a. exit rays striking the IR

quality assurance of digital imaging requires the uniformity of processing codes to ensure a. image appearance consistency b. faster throughput c. less heat loading on the anode d. smoother integration into pacs

a. image appearance consistency

distortion may be describes as a. misrepresentation of an anatomic structure on the image b. foreshortening c. elongation d. magnification

a. misrepresentation of an anatomic structure on the image

the expression of image quality provided by a detector is called a. mtf b. matrix size c. snr d. nyquist frequency

a. mtf

a primary advantage to digital fluoroscopy is a. post processing manipulation of the image b. radiation dose to the patient is substantially lower c. no radiologist is needed d. lower cost

a. post processing manipulation of the image

which of the following describes the relationship between mas and receptor exposure a. receptor exposure is directly proportional to mas b. receptor exposure is inversely proportional to mas c. receptor exposure is directly proportional to mas^2 d. mas controls the number of electrons boiled off the anode and the number of xrays produced

a. receptor exposure is directly proportional to mas

the 15% rule states that a. receptor exposure may be halved by decreasing kvp 15% b. kvp should be 15% of the mas selected c. receptor exposure may be halved by increasing kvp by 15% d. at least a 15% change in mas is required to make a change visible

a. receptor exposure may be halved by decreasing kvp 15%

If SID is reduced by one half, what must be done to mAs to maintain a constant receptor exposure? a. reduce mas to one fourth its original value b. reduce mas to one half its original value c. increase mas by four times its original value d. increase mas by two times the original value

a. reduce mas to one fourth its original value

digital image receptors are more sensitive to a. scatter and background radiation b. fluorescent lights c. free electrons d. free radicals

a. scatter and background radiation

Beam part receptor alignment latitude describes a. the latitude of collimation that still allows the software to detect collimated edges b. the alignment that maintains alara requirements c. exposure latitude d. acceptable distortion of the image

a. the latitude of collimation that still allows the software to detect collimated edges

Choose all factors below that result in poor spatial resolution (choose 4): A. Long SID B. Long OID C. Large focal spot D. Small focal spot E. Patient motion F. Magnification

b,c,e,f

the actual patient dose as measured by a meter embedded in the collimator is a. RAD-radiation absorbed dose b. DAP-dose area product c. REM- radiation equivalent man d. doubling dose

b. DAP-dose area product

A high SNR provides an image with: a. Poor spatial resolution b. Higher spatial resolution c. Poor contrast d. Higher distortion

b. Higher spatial resolution

the smallest resolvable area in digital imaging device is a. detector size b. detector element c. matrix size d. focal spot size

b. detector element

the range of exposures that provides a quality image is called a. detector latitude b. exposure latitude c. histogram d. dynamic range

b. exposure latitude

which of the following describes the relationship between receptor exposure and the use of grids a. grids always reduce receptor exposure b. grids reduce receptor exposure unless mas are increased to compensate c. grids reduce receptor exposure by only absorbing scatter radiation d. receptor exposure increases as grid ratio increases

b. grids reduce receptor exposure unless mas are increased to compensate

in digital fluoroscopy, what equipment should be used to view the image a. conventional view box b. high resolution monitor capable of displaying millions of pixels c. high definition television d. plasma television required

b. high resolution monitor capable of displaying millions of pixels

the primary controlling factors of receptor exposure are a. kvp and mas b. mas and sid c. sid and oid d. sid, oid, fss

b. mas and sid

The number of pixels making up the digital image is the a. pixel depth b. matrix size c. pixel pitch d. field of view

b. matrix size

optimal spatial resolution may be created using which of the following factors a. large focal spot b. narrow pixel pitch c. long oid d. short sid

b. narrow pixel pitch

the active portions of a CR IP are a. abc b. psp c. dqe d. snr

b. psp

a material that absorbs xray energy and emits part of that energy as visible light is called a. diode b. scintillator c. tft d. cathode

b. scintillator

elongation and foreshortening are examples of a. size distortion b. shape distortion c. motion d. distortion caused by short sid and long oid

b. shape distortion

which of the following affects receptor exposure a. atomic mass of the xray tube anode b. xray tube angle c. atomic number of the cathode filament

b. xray tube angle

which of the following maintains image brightness over a wide range of exposures a. aec b. bit depth c. automatic rescaling d. detector size

c. automatic rescaling

as the amount of beam filtration is increased a. contrast increases b. there is no effect on contrast c. contrast decreases d. contrast increases because the beam is harder

c. contrast decreases

receptor exposure was formerly called a. contrast b. detail c. density d. distortion

c. density

quality assurance and maintenance of cr cassettes include cleaning and inspecting plates at least a. daily b. every 48 hours c. every 3 months d. weekly

c. every 3 months

which of the following governs the relationship between sid and receptor exposure a. reciprocity law b. 15% rule c. inverse square law d. ohms law

c. inverse square law

the number of electrons boiled off the cathode and consequently the number of xrays produced are controlled by a. kvp b. sid c. mas d. oid

c. mas

The appearance of digital images on technologists monitors is: a. the same as on radiologists monitors b. substantially better than on radiologists monitors c. not as good as on radiologists monitors

c. not as good as on radiologists monitors

If the exposure field is not accurately recognized, the histogram will contain data: a. outside the exposure field, narrowing the histogram b. inside the exposure field, widening the histogram c. outside the exposure field, widening the histogram d. inside the exposure field, narrowing the histogram

c. outside the exposure field, widening the histogram

as speed class decreases a. a. the likelihood of noise increase b. noise is unaffected c. patient exposure increases d. sharpness decreases

c. patient exposure increases

the space from the center of a pixel to the center of the adjacent pixel is called a. pixel density b. bit depth c. pixel pitch d. matrix depth

c. pixel pitch

As beam restriction increases (becomes tighter) a. receptor exposure increases b. receptor exposure increases as a result of focusing of xrays c. receptor exposure decreases d. receptor exposure is not affected

c. receptor exposure decreases

Grid ratio is defined as the a. the ratio of lead strips to the space between them b. the thickness of the lead strips divided b the thickness of the aluminum interspacers c. the ratio of the height of the lead strips over the distance between the lead strips d. the ratio of the distance between the lead strips over the height of the lead strips

c. the ratio of the height of the lead strips over the distance between the lead strips

the smallest exposure change able to be captured by a detector is called a. spatial resolution b. exposure latitude c. pixel d. contrast resolution

d. contrast resolution

in digital radiography inappropriate collimation causes a. a fogged image b. pixel unresponsiveness c. dicom incompatibility d. histogram analysis error

d. histogram analysis error

what effect dose beam restriction have on contrast a. decreases contrast by focusing the xray beam b. decreases contrast because of higher kvp level used c. decreases mas to reduce the number of compton interactions taking place d. increase contrast because of reduction in the number of compton interaction that occur

d. increase contrast because of reduction in the number of compton interaction that occur

the adjustment in technical factors required when using beam restriction is a. increase kvp b. decrease kvp to reduce the number of compton interactions taking place c. decrease mas to reduce the number of compton interactios taking place d. increase mas to compensate for the number of rays removed from the primary beam

d. increase mas to compensate for the number of rays removed from the primary beam

what effect does the use of radiographic grids have on contrast a. decreases contrast b. increases contrast c. no effect d. increases contrast by absorbing scatter radiation

d. increases contrast by absorbing scatter radiation

Use of technique charts: a. is unnecessary for any exam because of AECs b. does not require that the part thickness be measured with calipers c. is usually based on fixed mAs and variable kVp d. is helpful when manual techniques are used

d. is helpful when manual techniques are used

which of the following terms describes the highest spatial frequency that can be recorded by a digital detector a. spatial resolution b. contrast resolution c. mtf d. nyquist frequency

d. nyquist frequency

what converts light into a charge a. diode b. cathode c. ac to dc converter d. photodiode

d. photodiode

differential absorption of the xray beam is a function of a. compton interaction b. atomic mass of anatomic structure c. mas d. photoelectric interaction

d. photoelectric interaction

if sid is doubled, what may be said about receptor exposure a. receptor exposure doubles b. receptor exposure is reduced by one half c. receptor exposure is reduced by new mas^2 d. receptor exposure is reduced to one fourth

d. receptor exposure is reduced to one fourth

The portion of contrast that is caused by variations in the anatomy or is secondary to pathological changes is called a. radiographic contrast b. anatomic contrast c. pathologic contrast d. subject contrast

d. subject contrast

Quantum noise limits ability to see: a. Detail b. Contrast c. Fatty tissue d. Additive pathologies

a. Detail

The use of filtration: A. Greatly reduces receptor exposure because of the absorption of short-wavelength x-rays B. Greatly reduces radiographic receptor exposure because of the absorption of high-energy x-rays C. Increases radiographic receptor exposure by removing long-wavelength x-rays D. Has little effect on receptor exposure because x-rays removed from beam are not image-producing rays

D. Has little effect on receptor exposure because x-rays removed from beam are not image-producing rays

When AEC is used, increasing the KVP: A. Increases the exposure time B. Increases the image contrast C. Decreases the exposure time D. Has no effect on image quality

D. Has no effect on image quality