Midterm Examination Flashcards
It is the generation of data that can be manipulated with a computer
Data Acquisition
A small battery-powered chip that stores critical system information such as the date, time, and hardware configuration.
CMOS
Which of the following is not part of raw data acquisition?
Exposure Positioning Technique
A data converter which generates an analog output from a digital input
ADC
ADC stands for:
Analog to Digital Conversion
Other term for edge enhancement
High-pass filtering
It refers to the overall lightness or darkness of an image
Brightness
Other term for automatic collimation
Exposure Field Recognition
Steps in digitizing the signal
- Scanning
- Reading
- Quantization
- Sampling
Correct answer: 1,4,3
It is a measure of radiation used to produce an ideal diagnostic image on the receptor
Exposure Indicator Determination
A graphical display of pixel intensity distribution for a digital image
Histogram
Factors that affect the exposure indicator
- kVp
- mA
- s
- SID
Correct Answer: 1,2,3,4
It produce an image at the correct preset brightness level even when the exposure is too high or low
Automatic Rescaling
It is the process of changing the pixel brightness and contrast
Windowing
Structures appear dark or black in the radiographic image
Radiolucent
It allows gray-scale values in the recorded image to be remapped to new values to improve the final image
Look-up table
Structures appear light or white in the radiographic image
Radiopaque
It is also known as low-pass filtering or blurring filter
Smoothing
It is also referred to as Dynamic Range Compression (DRC) which employed to reduce the file size by subtracting the extreme light and dark areas of image
Equalization
It provides the radiographer with an indication of the accuracy of their exposure settings for a specific image
Vendor-specific Values
A device that s place between the patient and the IR
Grid
The absorption of useful radiation by a grid is called
Grid Cutoff
Which type of error results in grid cutoff at the periphery of the radiographic image
Off-focus
Type of grids that is not grid placement error
Air-gap grid
Limiting patient exposure and reducing the amount of scatter radiation produced within the patient
Beam Limitation
Selection of kVp and mAs to produce acceptable image quality with minimum dose.
Optimal Exposure
It is also called “lateral decentering”
Off-center Grid
It is the most common type of grid cutoff and can occur from either the tube or the grid being angled.
Off-level Grid
It occurs when the SID is less than or greater than the focal range.
Off-Focus Grid
Collimated borders are not recognized and having multiple images in a single plate
Exposure Field Recognition Errors
It occurs when a focused grid is placed upside- down on the IR.
Upside-down Grid
Using a T-cage factor in a chest x-ray
Incorrect Anatomic Selection
Presence of prosthetic device or other parts with large density differences
Unexpected Material in Data Set
Improper assessment of patient size and stature.
Large Overexposure Error
Error in locating the values of interest (VOI) due to an excess exposure from poor collimation techniques
Inappropriate Rescaling
Determine the number of x-rays in the beam and therefore radiation quantity
mAs
It is the simplest type of grid.
Parallel Grid
A type of grid with the highest contrast improvement factor.
Crossed Grid
It is also called automatic collimator.
Positive Beam Limiting Device
A device that is placed between the anatomic area of interest and the IR to absorb scatter radiation exiting the patient.
Grid
Who invented the radiographic grid?
Gustav Bucky
The ratio of the height of the lead strips to the width of the interspace material
Grid Ratio
It is the distance between the source of the radiation and affects the amount of radiation reaching the patient
SID
Controls radiation quantity, optical density and patient dose
mAs
The controlling factor of contrast is:
kVp, which controls the quality of x-rays produced at the target
As screen speed increases, radiation dose to patient
Decreases
A law that state’s that the intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation
Inverse Square Law
ALARA stands for
As Low As Reasonably Achievable
If a radiographic exposure was made using the 200 mA selection with 0.5 seconds, what would the mAs be?
100
A quality image is produced using 80 kVp at 10 mAs with as 6:1 ratio grid. Calculate the change in exposure technique when changing to a 12:1 ratio grid.
80 kVp at 17 mAs
Formula of Inverse Square Law
I1/I2=(d2/d1)^2
Formula of grid controlling factor
GCF= mAs with grid/mAs without grid
Formula of grid ratio
Grid ratio = h/D
Wrist joint radiographic examination requires 40 machine constant and thickness measures 5 cm. What will be the KVp?
50
What is the grid ratio when lead strips are 3.2 mm high and separated by 0.2 mm?
16:1
A quality radiograph is obtained using 2 mAs at 70 kVp without using a grid. What new mAs is needed adding a 12:1 grid to maintain radiographic density?
10
If an excellent knee radiograph is produced using 10 mAs and an 8:1 ratio grid, how much mAs will be needed if no grid is available?
2.5 mAs
An exposure of 70 mAs produced an acceptable radiograph at a source-to-film distance of 60 inches and an exposure was measured at 30 mR. What will be the measured exposure if the SID will be decreased to 30 inches?
40 mR
A satisfactory radiograph was made using a 40-in SID, 10 MAS, and a 12:1 grid. If the exam will be repeated at a distance of 48-in and using an 8:1 grid, what should be the new mAs in order to maintain the original density?
5.6 mAs
The intensity of radiation at an SID of 40 inches is equal to 500 mR. What is the intensity of radiation when distance is increased to 56 inches?
255.1 mR
