Physics Unit 3 Exam - Ch. 30, 31, 32

Any image layer can be: 1. ___________ 2. __________ 3. __________

1. boosted/amplified 2. suppressed 3. removed from stack

List the three general approaches to processing any digital images: 1. ______ _______ 2. _____ _________ 3. _______ _________

1. spatial domain 2. intensity domain 3. frequency domain

For each of the following pre-set parameters used by Fuji for gradient processing, write in what the abbreviation stands for: 1. GT = gradation _______ 2. GS = gradation _______ 3. GA = gradation ______ 4. GC = gradation ________

1. type 2. shift 3. amount/angle 4. center

Anything which can lead to histogram analysis errors can cause the exposure indicator to be corrupted. List below four examples: 1. _______________ 2. ______________ 3. _________________ 4. ________________

1. unexpected material in the field 2. collimation margins not detected 3. delay in processing 4. exposure field recognition error ps sorry i picked all the short ones cuz im lazy

Also, an image saved into the PAC system under a different algorithm is saved under a changed ___________ header as a different procedure, complicating record-keeping.

DICOM

Remnant current flowing in DR

Dark current

As a guideline to acceptable exposure levels, the ________ __________ is being implemented by all manufacturers. The index ranges from +3 (twice the ideal exposure) to -3 (indicating 1/2 ideal exposure.) Digital images should not be repeated unless saturation or mottle are evident.

Deviation Index

_____ _______ _________________ allows the separation of soft tissue only images from bone only images, of particular interest in chest imaging.

Dual energy subtraction

_______________ ___________ errors may result from scatter radiation, extreme over or under exposure, unexpected materials, histogram errors or delays in processing.

Exposure Indicator

________ _____________ corrections include adjustments for flaws in digital acquisition hardware and Del drop - out effects. Software can be configured to fill in pixel values dead hardware pixels, and to adjust for flat-field non-uniformity, by interpolation.

Field uniformity

The mathematical method by which a complex wave form representing one line of a digital image can be broken down into a set of the different individual wavelengths that make it up known as _________ ____________.

Fourier Transformation

Domain sorted according to size of objects or details

Frequency

___________ or gradient processing fine-tunes the image brightness and gray scale by feeding rescaled pixel values into a LUT that is customized for the particular anatomy of interest.

Gradation

________ ___________ is used both as default processing operation and again any time the displayed image is windowed by the operator.

Gradation processing

Sorting an image by the intensities of its pixels results in a ___________.

Histogram

For Gradation Processing, the rescaled data set is fed into an anatomical ____ that was determined when the operator selected the procedure at the console.

LUT

List of Q values assigned to each exam

LUT

A "suspend" button holds two studies simultaneously for review before sending either to the _____.

PACs

AKA, image refinement

Post - processing

List below a summary of the generic steps in digital radiograph prcoessing: Preprocessing: 1. 2. 3. 4. Postprocessing: 5. 6. 7. Image Displayed: 8. 9.

Preprocessing: 1. Field uniformity corrections 2. Noise and Del dropout corrections 3. Image and Histogram analysis 4. Rescaling (processing) Postprocessing: 5. Detail processing 6. Gradation Processing (LUTs) 7. Formatting for display Image Displayed: 8. Operator adjustments 9. Applications of special features

_____________ is a form of low-pass filtering that softens edges and reduces noise.

Smoothing

Area of information relevant to image formation

VOI

The _____ is a range within the histogram that can be relocated to accentuate different tissue types in the image.

VOI

In CR phosphor plates and indirect-capture DR detectors, different portions of the phosphor layers have slightly greater ______________ efficiency and produce more light than other areas.

absorption

The gray level (brightness or density) of each pixel becomes the ____________ of the waves in this graph.

amplitude

Flat field uniformity corrections even out the _____________ across the area of the image field.

brightness (signal)

Any type of artifacts that have ________ and ______ characteristics can be identified by computer software for elimination from the image.

consistent, unique

A steeper gray scale curve superimposed over the histogram indicates higher image ______.

contrast

Background exposure left on a CR PSP

dark noise

High frequency means that there are fewer pixels per detail in the image, and this translates into higher image ___________.

detail/sharpness

For an acquired histogram with a bizarre shape, failure to properly locate the expected landmarks is a common cause of _______ _____________ errors.

digital processing

____________ _______ is the range of different gray levels made available by a computer system including its installed software.

dynamic range

The net result is ____ ____________ (high-pass filtering).

edge enhancement

Unsharp mask filtering

edge enhancement

An example of different terms used by different manufacturers is GEs "look" feature It's "hard" look setting actually engages ______ ___________ and the "soft" look setting actually engages a __________ algorithm.

edge enhancement, smoothing

Compression of the gray scale

equalization

Histogram analysis failure is less common with DR systems because they include only the __________ pixels or dexels in the image data base, whereas CR systems scan the entire plate.

exposed

The computer must also distinguish darker anatomical structures from the "background density" in the image field. This process is called exposure __________ recognition.

field

corrections including flat field, gain offsets, light guide variations

field uniformity

In which of the general digital processing domains is the image sorted out according to pixel values?

frequency

In the ________ _______, the amplitude (height) of the wave represents a brightness level or pixel level, whereas the frequency or length of the wave represents the size of a structure of the number of pixels occupied by it along a particular row.

frequency domain

Detail processing can be performed either in the __________ domain or in the ______ domain.

frequency, spatial

Gradual passing from one tint to another

gradation

For an image that already has a long _____ _____, applying a smoothing function can lead to loss of details, for an image already has high contrast, applying edge-enhancement can lead to noise.

gray scale

This roughly rescales the _________ __________ of the image.

gray scale

To achieve exposure indicators within the correct recommended range, it is essential that _____ kVp, _____ mAs technique combinatiions be utilized.

high, low

Bar graph representing pixel count vs pixel density

histogram

The "Q values" in a permanent look-up table represent the "ideal" __________ for each particular anatomical procedure.

histogram

To analysis a ___________, the computer scans in from each end of the data set, searching for identifiable landmarks created by changes or trends in the pixel counts in each "bin" or file.

histogram

A look-up table really is a simple table with just two columns: One for _______ and one for _______.

input, output

domain sorted strictly by the values of the pixel

intensity

The speed of any imaging system expresses its sensitivity to radiation, and is always _______ related to the amount of exposure required to produce an adequate signal at the image receptor.

inverse

To analyze the histogram for landmarks, the computer scans __________ from both right and left ends of the histogram.

inward

Sub-matrix averaging to correct DEL drop - out

kernel

The larger the size of the _____ matrix used, the wider the region used for averaging, and the more "blurred" the mask image appears.

kernel

Type 3 histogram analysis allows for large boluses of positive contrast agents, shielding or appliances to be included in the projection. It anticipates a third lobe, a "spike" to the ____ in the acquired histogram.

left

In an image that already has ___ contrast, applying smoothing can lead to loss of detail.

low

High-pass frequency filtering does not replace some of the _______ - frequency layers (gross structures).

lower

In this way, a ____ is maintained of where each pixel value belongs throughout histogram processing.

map

To resize an image, the pixels are mapped onto a smaller or larger image ______.

matrix

When PACS images are brought up for display on a particular monitor screen sizing of the ______ must fit the that of the monitor, and the scaling of brightness and contrast must match the dynamic range of the display monitor.

matrix

The full range of acquired image data is used, ranging from S _____ to S ______.

min, max

Nearly all modern CR and DR systems can be operated at a speed class of 300, 350, or 400, without the appearance of substantial _____ in the image.

mottle

Smoothing algorithms, sometimes called "noise compensation," can be used to suppress moderate amounts of ________ in an image.

mottle

Re-mapping means that regardless of the specific input values (S values), the ______ values (Q values) are always the same.

output

If any details at all can be made out in the dark portion of the image, it may be _________________ but NOT necessarily saturated.

over-exposed

For these reasons, rescaling can align image brightness perfectly, but can only align image gray scale _________.

partially

Two general types of noises are _______ noise and _______ noise.

periodic, random

Computer system cannot adjust this value

pixel count

The computer can adjust the levels and ranges of pixel values, but cannot change the______ _______ for any particular value.

pixel count

After corrections have been made for data acquisition , additional operations targeted at refinement of the image, whether made by the computer or by a radiographer, are properly classified as ______ - processing.

post

Image ____ -processing includes gradation processing, detail processing, preparation for display, and adjustments and features applied by the operator to the final displayed image.

post

All corrections that are made to the "raw" digital image data due to flaws in image acquisition fall under the term _____ - processing.

pre

Correction for flaws in the original image acquisition

pre-processing

_______________ consists of corrections for flaws in acquisition of the original image, image analysis, and normalization.

pre-processing

At the console, selecting the __________ algorithm assigns the type of histogram analysis to be used.

procedure.

The reduction of random noise such as ________ ________ is best achieved with spatial (kernel) processing, whereas the suppression of periodic noise caused by hardware is best achieved by frequency processing.

quantum mottle

An exposure less than 80% of the EI T should not be repeated unless a __________ finds the level of mottle in the image unacceptable.

radiologist

The separated frequencies can each be amplified, modified, or eliminated individually, before _____________ them into the final image.

recomposing/adding

Rescaling is simply a process of algebraically "______________" incoming data.

relabeling

Radiographs presenting severe mottle from underexposure should be ___________.

repeated

Most _________ (normalization) methods use software that algebraically re-labels input pixel values such that the output values are always the same. To accomplish this, the range of S values acquired must match the range of Q values in the permanent output LUT.

rescaling

Normalizing, brightness adjustment.

rescaling

Depending on the degree to which incoming pixel values are _________ up or down by digitization, they can be made to fit a pre-set range of S values.

rounded

AKA, partial pattern recognition

segmentation

For a digital image, high-frequency translates to high _________ of detail, because each detail occupies fewer pixels.

sharpness

By reducing noise in any form, all-important _____ __ ______ ______ is enhanced.

signal to noise ratio

Reduction of noise on image or soften details

smoothing

Tissue, equalization or contrast equalization can stimulate the traditional ______ _______ technique.

soft tissue

domain sorted by pixel location

spatial

When processing an image in the ______ _______, it is sorted according to pixel location; in the intensity domain, the image is sorted by pixel value, and in the frequency domain it is sorted by object size.

spatial domain

A ______ ______ can be used for detail processing by placing multiplication factors in its cells and passing it over the image column-by-column and row-by-row. Depending on the factors by which pixel values are multiplied, the kernel may execute smoothing, edge-enhancement, or background suppression on the image, and can also affect overall image contrast.

spatial kernel

Since the bit depth of a computer can far exceed the range of human vision, memory _____ ______ can be saved by not using the entire bit depth of the system.

storage space

A kernel may be defined as _______ ________ that is passed over the original image matrix, executing a mathematical function on it.

sub matrix

Kernel operations pass a smaller _____ ______ of core values over each pixel row by row, then column by column, assigning new pixel values.

sub matrix

Pitch black peak representing direct exposure to IP

tail

Type 2 histogram analysis is essential for projections of large body parts, such as the abdomen, which may leave no "background density" to work with. It operates on the assumption that there will be no ____ in the histogram shape.

tail or tail spike

When processing speed is changed, or when the kVp range is dramatically changed, a new _________ must be established.

target EI

The use of a smoothing algorithm cannot recover information lost from ____________.

under exposure

To accentuate particular anatomy, a particular target range of densities from the image can be selected to operate on. This range is defined as the _______ of interest, (VOI).

values

These are the same formulas applied whenever the radiographer __________ the image after it is initially displayed.

windows