Advanced Principles, Unit 4

An S number of ________ is half the exposure of an S number of 200, and an S number of ______ is twice the exposure of an S number of 200.

400; 100

In an Agfa system, each step of _______ above or below 2.6 equals an exposure factor of 2.

0.3

The S number (in Fuji, Phillips or Konica systems) is the amount of luminescence emitted at _____ mR at _______ kVp, and it has a value of 200.

1, 80

Match the following image artifacts with their causes. 1. Phantom or ghost images 2. Light spots 3. Histogram analysis errors 4. Exposure Field Recognition error 5. Visible grid lines on the image 6. DEL drop out artifacts 7. An image of the detector electronics superimposed over the anatomy A. Incomplete erasure of Image plate or extreme overexposure B. Dust or other foreign material on the receptor C. Poor grid alignment D. Non-parallel collimation E. Backscatter radiation F. Damaged or faulty section of DR receptor G. Improper collimation, improper technique selection, or beam alignment errors

1. A 2. B 3. G 4. D 5. C 6. F 7. E

An lgM (for an Agfa system) of ______ equals twice the exposure of 2.6 lgM, and an lgM of ______ equals an exposure half that of 2.6.

2.9; 2.3

For a Fuji system, the mid value S number is ___________ and the relationship to the exposure is __________.

200, indirect

For a Carestream system, the mid value EI number is ____________ and the relationship to the exposure is __________.

2000, direct

The human eye can detect up to ___________ shades of grey. 20 30 40 50

30

In a Kodak Carestream system, an EI number plus ________ is equal to a doubling of exposure, and an EI number of minus ________ is equal to a halving of exposure (same answer for both blanks).

300

What is the IEC 62494-1? An error that occurs when a receptor is overexposed A standard that provides common EI values for use with all types of digital image receptors. A QC tool used to assess the grayscale of an image An image compression technique

A standard that provides common EI values for use with all types of digital image receptors.

Which of these technologist mistakes is most likely to cause processing errors within in a computed radiography system? Incorrect focal spot selection Failure to include a radiographic marker Incorrect source-to-image distance Asymmetrical collimation

Asymmetrical collimation

Higher spatial frequency indicates ____________ spatial resolution. Better Worse

Better

The lowest exposure readings on a radiographic histogram usually represent areas of: Soft tissue Calcification Unattenuated exposure Collimation

Collimation

Software that is designed to assist the radiologist by detecting small imperfections in the anatomy. PBL (positive beam limitation) AEC (automated exposure control) CAD (computer aided detection) SNR (signal to noise ratio)

Computer aided detection (CAD)

The ability of the image receptor to distinguish between objects having similar subject contrast.

Contrast resolution

The process of squeezing digital content into a smaller electronic space.

Data compression

______________ occurs when there is too much exposure to the image receptor. The oversaturated elements of the IR show up as blank on a radiograph, and they can be mistaken for pathologies.

Data drop

Which of the following identifiers are required by law to be included on a radiographic image? Date of the examination Exposure indicator Referring physician All of the above

Date of the examination The law requires that the date of examination be included with each radiographic image. The exposure indicator and referring physician are commonly included, but these are not legally required.

Measure of how sensitive and accurate incoming data is converted to output viewing.

Detective quantum efficiency (DQE)

A value that reflects the difference between the desired or target exposure to the IR and the actual exposure to the IR. Deviation index (DI) Exposure indicator (EI) Kilovoltage peak (kVp) Milli-amperage seconds (mAs)

Deviation index (DI)

An exposure of 80 kVp and 10 mAs results in an S# of 600. What change would be needed to bring the S# into the suggested manufacturer's range of 100-400? Double the mAs Half the mAs Quadruple the mAs Half the kVp

Double the mAs The S# should decrease to approximately 300.

The number of gray shades that an imaging system can reproduce.

Dynamic range

When reviewing the radiographic exposure indicator, an S number significantly below 200 indicates: Insufficient image contrast Excessive image contrast Insufficient receptor exposure Excessive receptor exposure

Excessive receptor exposure The ideal S number is 200. The S number system is inverse, a low number indicates a high exposure and a high number indicates a low exposure.

The appearance of saturation artifact on a radiograph is caused by: Inadequate receptor exposure Excessive receptor exposure Incorrect post-processing Small matrix size

Excessive receptor exposure fac

A numeric representation of the quantity of exposure received by a digital image receptor. Deviation index (DI) Exposure indicator (EI) Kilovoltage peak (kVp) Milli-amperage seconds (mAs)

Exposure indicator (EI)

The range of exposures that can be used to produce an acceptable image.

Exposure latitude

A software correction that is performed to equalize the response of each pixel to a uniform x-ray beam.

Flatfielding

A radiographic histogram is a graphic representation of: Spatial resolution relative to contrast resolution Signal-to-noise ratio Patient dose estimations Frequency of specific exposure values

Frequency of specific exposure values

Incomplete erasure of a computed radiography image receptor may produce an artifact called:

Ghost image

The process of identifying the values of interest in a radiographic histogram is called: Histogram analysis Rescaling LUT conversion Post-processing

Histogram analysis

Physical damage to the structure of a computed radiography image receptor is likely to manifest on a radiograph as: Loss of contrast Loss of spatial resolution Geometric distortion Hyperdense (bright white) artifact

Hyperdense (bright white) artifact

Pixel malfunction within a computed radiography or digital radiography image receptor is likely to manifest on a radiograph as: Loss of contrast Loss of spatial resolution Geometric distortion Hyperdense artifact

Hyperdense artifact

Brightness and contrast are a function of ______________________, NOT of exposure.

Image processing

The appearance of quantum mottle on a radiograph is caused by: Excessive receptor exposure Incorrect post-processing Small matrix size Inadequate receptor exposure

Inadequate receptor exposure

Processing a radiographic image using the wrong histogram protocol may result in visible errors such as: Inadequate spatial resolution Increased image noise Saturation artifact Incorrect contrast and brightness

Incorrect contrast and brightness Using the wrong histogram protocol may result in incorrect contrast and brightness in the radiographic image. Spatial resolution, noise, and saturation are not usually affected by the histogram selection.

When reviewing the radiographic exposure indicator, an S number significantly above 200 indicates: Insufficient image contrast Excessive image contrast Insufficient receptor exposure Excessive receptor exposure

Insufficient receptor exposure

Estimating a value within the range of measured data. Interpolation Decimation Averaging

Interpolation

The abrupt increase in absorption that occurs in an atom that is hit by an x-ray photon that is just higher than the k-shell binding energy of that atom.

K-shell absorption edge

Which of the following identifiers are required by law to be included on a radiographic image? (Select all that apply) Technologist initials or identification number Patient's social security number Location of the examination Right or Left marker

Location of the examination Right or Left marker A radiographic image must include the location of the examination and a right or left marker, as well as the patient's name, date of birth, and the date the exam was performed. The technologists initials is not required by law.

Which term describes the process of adding brightness and contrast to exposures values within a radiographic image? Histogram analysis Rescaling Lookup Table conversion Post-processing

Lookup Table conversion

A data compression algorithm that allows the original data to be perfectly reconstructed from the compressed data.

Lossless compression

Data compression techniques in which some amount of data is lost. This technique attempts to eliminate redundant information.

Lossy compression

Plots the fidelity (degree of exactness or accuracy) of the object against the size of the object.

MTF curve

Which of the following exposure readings are processed as part of the "values of interest" within a radiographic image? (Select all that apply) Collimator leaves Patient anatomy Medical implants

Medical implants Patient anatomy The values of interest include all relevant medical information, including the patient's anatomy and medical implants. Only very high exposure readings (such as the unattenuated beam) and very low exposure readings (such as the collimation) are excluded from processing.

Measures the accuracy of a recorded image compared to the original object. It is a measure of recorded detail as a function of image contrast.

Modulation Transfer Function (MTF)

A technologist accidently performs a radiograph under the wrong patient name. How should this error be corrected? Annotate the image with the correct patient name Move the radiograph to the correct patient and correct requisition Repeat the exposure under the correct patient name No action is needed

Move the radiograph to the correct patient and correct requisition

A technologist received requisitions for a thoracic spine series and lumbar spine series on the same patient. The technologist accidently performs the lumbar series under the thoracic requisition. How should this error be corrected? Annotate the image with the correct requisition number Move the radiograph to the correct requisition number Repeat the exposure under the correct requisition number No action is needed

Move the radiograph to the correct requisition number

A technologist is using a variable kVp chart to set the exposure technique for a table-top radiograph. If the technique chart calls for 87 kVp but the technologist uses 82 kVp, the resulting image will likely demonstrate: Saturation artifact Quantum mottle Loss of contrast No visible errors

No visible errors

A technologist is using a variable mAs chart to set the exposure technique for a portable radiograph. If the technique chart calls for 1.5 mAs but the technologist uses 2.0 mAs, the resulting image will likely demonstrate: Saturation artifact Quantum mottle Loss of contrast No visible errors

No visible errors Overexposure only occurs when the exposure technique is several times more than necessary.

Any part of the signal that does not represent patient tissue. Noise Signal Contrast Scatter

Noise

As kVp is increased... Patient dose decreases, SNR increases Patient dose decreases, SNR decreases Patient dose increases, SNR increases Patient dose increases, SNR decreases

Patient dose decreases, SNR decreases SNR decreases because noise increases. More Compton interactions occur in relation to photoelectric interactions when kVp is increased.

As mAs is increased.... Patient dose decreases, SNR increases Patient dose decreases, SNR decreases Patient dose increases, SNR increases Patient dose increases, SNR decreases

Patient dose increases, SNR increases

Which of the following identifiers are required by law to be included on a radiographic image? (Select all that apply) Patient's date of birth Patient's name Patient's address Patient's medical record number (MRN)

Patient's date of birth Patient's name MRN may be included, but is not required by law. Also the date performed, exam location, and a radiographic marker must be included.

Appears as a result of incomplete image plate erasure. Quantum mottle Saturation Phantom image Hyperdense artifact

Phantom image

An acceptable image is the result of a multitude of factors, including technical factor selection, subject density, contrast, pathology, and processing.

Pyramid problem

On a Agfa system an exposure of 85 kVp at 40mAs of a cross-table lateral hip resulted in a lgM of 2.0. What change in mAs is needed to bring the lgM to the median of 2.6? Double the mAs Half the mAs Quadruple the mAs Half the kVp

Quadruple the mAs (X4) Each doubling of the mAs would increase the lgM by 0.3.

A technologist is using a variable mAs chart to set the exposure technique for a portable radiograph. If the technique chart calls for 12 mAs but the technologist uses 1.5 mAs, the resulting image will likely demonstrate: Saturation artifact Quantum mottle Loss of contrast No visible errors

Quantum mottle

The Digital Imaging and Communications in Medicine (DICOM) data associated with a radiographic image usually does NOT include: Exposure indicator Name of the facility Patient's name Radiographic marker

Radiographic marker DICOM data does not include the radiographic marker. The marker should be physically included on the image itself as a part of the exposure.

A technologist received a requisition for a two view knee radiograph, but the technologist performed a two view tibia-fibula series. How should this error be corrected? Request a new order to include the examination performed Adjust the order to match the examination performed Repeat the examination on the correct body part No action is needed

Repeat the examination on the correct body part

If a radiograph demonstrates an S number of 880 with severe mottle, the technologist should consider which of the following actions? Repeat the radiograph using a larger exposure technique Repeat the radiograph using a smaller exposure technique Repeat the radiograph using a larger grid ratio Submit the radiograph as-is without repeating the exposure

Repeat the radiograph using a larger exposure technique

If a radiograph demonstrates an S number of 12 with loss of soft tissue differentiation, the technologist should consider which of the following actions? Repeat the radiograph using a larger exposure technique Repeat the radiograph using a smaller exposure technique Repeat the radiograph using a larger grid ratio Submit the radiograph as-is without repeating the exposure

Repeat the radiograph using a smaller exposure technique

A dead detector element is visible within a radiograph of the orbits performed for MRI screening. This error should be corrected by: Repeating the exposure with a different image receptor Repeating the exposure with a different x-ray tube Reprocessing the raw data with a different histogram protocol Repeating the exposure after cleaning both the x-ray tube housing and the image receptor

Repeating the exposure with a different image receptor

A technologist accidently processes a chest radiograph under the abdomen histogram protocol. How should this mistake be corrected? No action is necessary Adjust the brightness and contrast in PACS Repeat the exposure using the correct histogram protocol Reprocess the raw data using the correct histogram protocol

Reprocess the raw data using the correct histogram protocol

The process of converting the original radiographic histogram to the expected histogram is called: Histogram analysis Rescaling Lookup Table conversion Post-processing

Rescaling

A technologist is using a variable kilovoltage peak (kVp) chart to set the exposure technique for a table-top radiograph. If the technique chart calls for 76 kVp but the technologist uses 140 kVp, the resulting image will likely demonstrate: Saturation artifact Quantum mottle Geometric blur No visible errors

Saturation artifact

The remnant beam incident on the IR that is converted to shades of gray eventually displayed on the monitor. Noise Signal Contrast Scatter

Signal

Expressed as lp/mm (line pairs per mm) and describes the spatial resolution.

Spatial frequency

Refers to the amount of details present on any image. The ability to render small high contrast objects. Also can be defined as the size of the object that can be viewed.

Spatial resolution

If a radiograph demonstrates an S number of 430 with no visible exposure errors, the technologist should consider which of the following actions? Repeat the radiograph using a larger exposure technique Repeat the radiograph using a smaller exposure technique Repeat the radiograph using a larger grid ratio Submit the radiograph as-is without repeating the exposure

Submit the radiograph as-is without repeating the exposure

If a radiograph demonstrates an S number of 80 with no visible exposure errors, the technologist should consider which of the following actions? Repeat the radiograph using a larger exposure technique Repeat the radiograph using a smaller exposure technique Repeat the radiograph using a larger grid ratio Submit the radiograph as-is without repeating the exposure

Submit the radiograph as-is without repeating the exposure. A repeat radiograph is only necessary when the image is visibly degraded by exposure artifacts such as mottle or saturation.

The highest exposure readings on a radiographic histogram usually represent areas of: Soft tissue Calcification Unattenuated exposure Collimation

Unattenuated exposure

The center gray shade in the range.

Window level

The range of gray levels available in an image.

Window width

As the spatial frequency of an object increases (the objects get smaller), the faithful reproduction of the object on the image gets __________. Better Worse

Worse