Quiz 4: Instrumentation and Quality Assurance Flashcards by Samantha Bishop

what type of mammography generators are all modern mammography generators?

high-frequency

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these generators rectify the input to produce a direct currect (DC) voltage waveform

high-frequency generators

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what is the difference between modern high-frequency generators and the older units?

the modern high-frequency generators essentially provide a constant potential with about 1% ripple

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with the modern high-frequency generators producing higher effective energy, what is the result?

higher x-ray output for a given kVp and mA setting

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why can’t general radiography tubes be used for mammograms?

the breast is made up of only soft tissues with very similar mass densities and atomic numbers that are better seen on a modified mammography machine

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what is the x-ray range found most useful in maximizing contrast in breast tissue?

in the range of 17-24 kiloelectron volts (keV)

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what type of x-rays does a Molybdenum (Mo) target produce?

characteristic in the 17-19 keV range after a photoelectric reaction

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what type of breast are ideal to image with a Molybdenum (Mo) target?

fatty breasts

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What type of x-rays does Rhodium (Rh) targets produce?

Bremsstrahlung xrays and K-Characteristic xrays

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How could you describe the properties of a K-Characteristic X-ray

20-23 range, which provides a better penetration of the dense breast

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What type of x-rays Does tungsten targets produce?

Bremsstrahlung x-rays

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What are the properties of A tungsten target?

Tungsten targets produce bremsstrahlung x-rays that predominate at energies above or below the 17 to 24 keV range

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Which type of target material is often referred to as admitting “harder” spectrum rays?

Tungsten

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What is the best target material that is used in mammography units?

Tungsten

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A target material that is sometimes more reliable and less expensive to manufacture

Single track tubes

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The target material that can support a higher anode heat load, that’s allowing for shorter exposure times compared with dual track x-ray tube’s

Single track x-ray tubes

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Is a target material that is especially useful when imaging large breasts

Single track x-ray tubes

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At target material that can support 2-3 times the maximum anode load compared with dual track tubes

Single track tungsten tubes

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What is beam filtration defined by the

Half-value layer (HVL)

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Shapes the emission spectrum of the x-ray beam and makes it compatible with the image receptor in breast characteristics of each patient

Added filtration

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With proper use of ______, the x-ray beam entering the breast will have very few photons above or below the preferred mammographic energy range.

Filtration

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In digital imaging, what does filtration do to exposure time?

Filtration reduces exposure time

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what is the minimun half-value layer (HVL)?

.30 mm (Al) at 30 kVp or .25 mm (Al) at 25 kVp

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what should the half-value layer (HVL) not exceed?

.40 mm AL at 30 kVp

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what 2 ways is the x-ray beam filtered

inherent and added

what all is included with inherent filtration?

glass/metal window of tube, oil in the tube housing, the mirror of the collimation assembly, and the compression paddle

What material is usually used as added filtration?

Aluminum (Al)

Positioned in the path of the emerging beam, thus affecting it’s penetrating power, which is defined by half value layer

Added Filtration

How often are test me done to ensure that the compression device is working properly?

Semi-annually

What are the MQSA standards for compression paddles

Minimum automatic compression should not be less than 25lbs (111 newtons N) Automatic compression should never exceed 45lbs (200 N) All unit should have a manual, hand controlled compression device, controlled by the technologist

What is the most often used material for the exit port of the mammography tube?

Beryllium (Be)

The area that electrons strike on the target

The focal spot

A small effective focal spot means a ________ target area.

Smaller

The target is angled to allow a larger area for the electrons to strike while maintaining a small effective focal spot

Line – focus principle

A small affective focal spot means a ___________ actual focal spot size

Large

Portions of the x-ray beam at the anode side of the table pass through the anode, resulting in a lower intensity beam

Anode Heel Effect

The thickest part of the breast (nearest the chest wall) is positioned at what side of the tube

Cathode

What are the possible anode angle ranges for mammography tubes?

0-16 degrees

What is a comment to tilt for a mammography unit?

6 degrees

What is the SID of a mammography tube?

60-75cm (24-30in)

Decrease in the target angle will the _______ effective focal spot

Decrease

What are the advantages of tube tilt?

Allows smaller target angle, Allows greater anode heating capacity, reduces anode heel effect

What type of focal spot is normal in mammography?

Dual focus

The larger focal spot may be _____ but is generally ______.

0. 4 | 0. 3

The smaller focal spot ranges from ______ to ________. What’s the most common size?

0. 15 to 0.1 mm | 0. 1

Routine imaging typically uses which size focal spot?

Large focal spot

Magnification imaging typically uses which size focal spot?

Smaller

What type of grid do modern mammography units use and why?

A moving grid to improve contrast

Are grids used with magnification mammography?

What affect do grids have on contrast?

Improves contrast

The grid ratio of mammography grids usually varies from _____ to ______ with an average grid ratio of _____.

3: 1-5:1 4: 1

What is a common range for grid frequencies?

30-50 lines per centimeter

What is grid interspace material made out of?

Carbon fiber or wood Something that is low attenuating.

What is the aim for a good image in mammography?

Small focal spot & long SID

How do you find out the magnification factor?

SID/SOD

What is the standard magnification factor?

1.5 times - 1.8 times

Increase magnification factor equals ______ to skin dose of patient

Increase

Allows the selection of at least 2 steps above and 2 steps below the normal density setting.

Density Composition Circuit

For a density compensation circuit, what does each step down/up translate to in terms of both mAs and optical density?

12% to 15% increase or decrease in mAs A 0.15 change in optical density

Why is there no collimation in mammography?

To prevent extraneous light from compromising the perception of fine detail when the radiograph is viewed.

What are the MQSA standards about collimation?

The collimation should not extend beyond any edge of the image receptor by more than 2% of the SID

In analog imaging, what does mAs affect?

Image density and patient dose

In digital imaging, what does mAs affect?

Patient dose

In digital, what term replaces density

Brightness

Are Image acquisition and display separated in digital imaging?

Yes

What all affects the brightness in digital imaging?

mA, the processing software, the digital algorithm

In analog imaging, what controls the contrast?

kVp

What can the mammography kVp range from? What kVp range is used in normal clinical practice?

20-40 kVp 25-28 kVp

How many AEC detector positions can be in each mammography unit?

What is the backup timer set for with grids? With no grids?

600 mAs 300 mAs

How many bits are in a byte?

Is controlled by the number of pixels

The image resolution

What are the 2 types of phosphors?

Turbid and needle

After the conductive later of the PSP, where do the electrons get trapped to form a latent image?

F-Trap

Is the term used to describe the time it takes for the latent image to disappear

Fading

How much energy of a latent image is lost after 8 hours?

25%

Is the emission of the bluish-purple light from electrons as they transition from higher energy to a lower energy state

Photostimulable luminescence (PSL)

Collects the blueish-purple light given off by the trapped electrons as they return to their normal neutral state

Photomultiplier Tube (PMT)

How often must IP’s be erased if not used?

48 hours

Are numeric data in the form of binary language

Digital signals

Are electrons or light

Analog signal

What are the 2 Digital Mammography systems available?

Indirect capture flat-panel detector & direct capture flat-panel detector

What are the 2 different names for flat-panel detector systems?

Scintillator-Based Non-Scintillator-Based

Which flat panel detector system is a direct process? How many steps are in this process?

Non-Scintillator-Based 2

Which flat panel detector system is an indirect process? How many steps are in this process?

Scintillator-Based 3

What are the 3 steps in a scintillator-based flat-panel-detector system?

X-ray beam strikes a scintillator(cesium iodide), Cesium Iodide converts X-ray to light, light strikes the photoconductor(amorphous silicon)

What are the 2 steps in a non-scintillator-based flat-panel-detector system?

X-ray beam strikes a photoconductor(amorphous selenium), a-Se converts xrays to electrons

Are located within the rows and columns on the TFT (Thin-Film Transistor)

Detector Elements (DEL or dexel)

What is a typical fill factor?

80%

Describes how efficient the system is in converting X-ray input signals into a useful output image

DQE (Detective Quantum Effeciency)

What is a significant advantage that flat-panel systems have over CM?

Flat-panel systems hav increased DQE (detective quantum effeciency)

During photon-counting image capture, how many images are acquired for resolution?

25 megapixels

What does the average glandular dose range on CC view?

0.4 to 0.8 mGy

What does the average glandular dose range on MLO view?

0.4 to 0.87 mGy

What is the recommended resolution for the radiologists monitors? The technologists monitors?

5 MP 2-3 MP

What is the newest type of high-capacity optical disk system that utilizes blue violet laser technology?

Ultra-density optical disk (UDOD)

A set of computer software standards that permit a wide range of digital imaging programs to understand each other.

Digital Imaging and Communications in Medicine (DICOM)

A computer network that allows images from multiple modalities to be viewed at a single monitor, transmitted, or stored.

PACS

All equipment used for this must be DICOM compatible

PACS

A networked electronic software system for managing diagnostic or therapeutic imaging and associated data.

Radiology Information System (RIS)

Is our Abbadox

Radiology Information System (RIS)

Is our Athena

Hospital Information System (HIS)

When was the MQSA Act passed?

October 27, 1992 Enforcement didn’t begin until 1995

Is a check of the detector and of the communication between the detector and AWS

Phantom Image

Measures the ability of the digital system to demonstrate objects of different brightness separate from their surroundings.

Contrast-to-noise-ratio (CNR)