Rad-103: Ch 6 Digital Image Processing, Display, and Health information Management

what are stages of digital processing

pre-processing

post-processing

what happens during pre-processing

data prepared for processing and display

what happens during post-processing

editing of the image through computer operation available before and after image is displayed

what are processes of digital data

histogram creation and analysis

automatic rescaling

look up table (LUT) application

what happens to raw image data before it can be displayed

several operations occur to prepare it so a quality image can be displayed

what type of imperfections is software correction applied to

bad pixels

dead pixels

what type of cassettes does software correction occur with

DR type IRs

what is flat fielding

process of correcting nonuniformity of pixel values throughout image

what is considered the first step in digital imaging processing

histogram creation

what is a histogram

graphic representation of a data set

what does a histogram include

all pixel values that represent the invisible image after software corrections applied

what is another term for a histogram

exposure histogram

what does a x-axis in histogram represent

range of pixel values assigned

what does y-axis in histogram represent

frequency of pixels for each value

what does location of graph along x-axis in histogram represent

image brightness levels

what does shape of histogram graph represent

image contrast (grayscale)

histogram analysis is an important processing technique for

identifying edges of an image

assessing exposure data/pixel value before image processing and display

what factors impact location and shape of histogram

anatomy imaged

exposure technique used

positioning used

collimation

what is histogram data compared to by a computer

stored preestablished histogram specific to the anatomic part imaged

what do stored histogram models have

distinct and characteristic shape based on anatomic region and projection

what is value of interest (VOI)

range of histogram data set that should be included in displayed imaged

in a raw exposure data histogram, what needs to be excluded and why

area outside of collimation to prevent processing error

what is automatic rescaling

process of mapping the gray scale to VOI to present a specific display of brightness

what does automatic rescaling maintain

consistent image brightness despite overexposure or underexposure

what does automatic rescaling not compensate for

underexposure

image noise

what can cause automatic rescaling errors

poor collimation

positioning

image artifacts

what is a LUT

method of altering the image based on reference histogram for image display

what kind of exposure response and dynamic range do digital detectors have

linear exposure response

wide dynamic range

what must be altered in raw images for improve visibility

image contrast

what does LUT alter and how

brightness and grayscale using computer algorithms

what happens to a LUT graph if original image is altered and why

no longer a straight light (S-shaped) due to different original pixel values

why is it important to choose correct LUT

anatomy appearance can be altered

what does calculation of pixel intensities in LUT display

differing contrast levels in an image

LUT creates a final look in terms of

brightness and contrast

what do exposure indicators provide in terms of exposure to IR

numeric value indication level of exposure to digital IR

what is a feature of digital imagining process

creating image with appropriate amount of brightness regardless of exposure to IR

how is numerical expression of exposure to receptor calculated

pixel VOI in histogram

what does exposure indicator assess

image quality in terms of noise

exposure indicator is NOT a measure of

patient exposure

what is symbol for exposure indicator

EI #

S #

varies between vendors

exposure indicator can be impacted by

collimation

positioning

kVp

how are target EI values determined

by department officials based on acceptable image quality standards

when was deviation index established

2008

what is deviation index

value that reflects the difference between the desired or target exposure to the image receptor and actual exposure of IR

DI value and actual exposure to IR

>+3.0 — Excessive exposure by a factor of 2 or 100% more than the EIt.

>+1.0 — Overexposed

<+0.5 — Exposure within target range

0 — No difference between target (desired) and actual exposure to IR

>−0.5 — Exposure within target range

<−1.0 — Underexposed

<−3.0 — Insufficient exposure by ½ or 50% of EIt.

what is dual-energy subtraction

technique that removes superimposed structures to make anatomic area of interest more visible

how is dual-energy subtraction possible digitally

computer subtracts selected brightness values

what is contrast enhancement

technique that alters pixel values to increase image contrast

what is edge enhancement (aka high-pass filtering)

postprocessing technique that improves visibility of small, high-contrast structures

what is a downside of edge ehancement

increased image noise

what is inversion

postprocessing technique that reverses grayscale of original image

what is soothing (aka low-pass filtering)

postprocessing technique that supresses image noise

what is downside of smoothing

decreased spatial resolution

what is equalization

postprocessing function where underexposed areas are made darker and overexposed areas are made lighter

what is benefit of equalization

image with lower contrast for better visibility of dense and lucent structures

what is region of interest in postprocessing

provides calculations of selected pixels values within area of interest to provide quantitative information about tissue

what is stitching in post processing

viewing multiple images as one

what is new technology for postprocessing

grid subtraction

scatter correction

what does new technology for postprocessing improve

image quality

reduced patient exposure

how are digital artifacts classified

according to origin

• equipment

• procedural

what can digital artifacts be related to

calibration of individual DEL, row, or column of detector matrix

artifacts during data extraction related to electronic readout mechanisms associated with rows and columns of DEL comprising detector matrix

erasure error

improper centering of CR to table grid

quality of image is affected by what features of a monitor

luminance

resolution

ambient viewing light and monitor

what is electronic masking

altering regions viewed on displayed image

what does window level do

set midpoint of range of brightness visible in image

• high level brightens image

• low level darkens image

what does window width do

varies range of shades of gray visible in image

• narrow increases contrast

• wide decreases contrast

what is the primary monitor for diagnostic interpretation

high-res 5-megapixel (2049 × 2560 pixels)

bit depth of 8 - 256 gray shades

what is display monitor diagonal measurement requirement

must be 80% of viewing distance

• 53 cm (21 in) for images sized 35 × 43 cm (14 × 17 in)

what is pixel pitch for standard image viewing

.200 mm at viewing distance of 60 cm (24 in)

what is aspect ratio

relationship between monitor width and height

• 3:4

• 4:5

• 16:9

• 16:10

what is luminance

measurement of light intensity emitted from surface of monitor

what is unit luminance is expressed in

candela per square meter (cd/m²)

what is luminance range for primary display monitors

1.0 cd/m² to 350 cd/m²

what is luminance ratio (LR)

ratio of maximum to minimum luminance

what is recommended LR

greater than 250

what does a monitor with a LR of 350 have

improved contrast

what does pixel bit-depth determine

contrast resolution

• 14 bit-depth yield 16384 shades of gray

how does LR affect contrast

higher ratio displays greater shades of gray

what are additional monitor concerns

geometric distortion

veil glare

display noise

what is AI applied to

digital data sets of medical images

what systems deal with managing patients health information

electronic health record (EHR)

health information systems (HIS)

medical image management and processing system (MIMPS)

what does health information management consist of

health informatics and data management

what does radiology specific health informatics deal with

collection

documentation

maintenance

protection and privacy

what is health information management

a complex system-wide effort to ensure that people, equipment, and processes are in place to expand healthcare communications and improve patient outcomes

modern radiology practice requires efficient and effective methods for

acquisition, storage, retrieval, transmission, and display of digital image from multiple modalities throughout healthcare systems

what do digital communication needs in radiology also include

processing and delivery of patient data

subsequent interpretation of radiological procedures

protected health information (PHI)

patients health related information that’s collected, stored, and shared

hospital information system (HIS)

stores PHI

electronic health record (EHR)

consists of all PHI on patient from all healthcare encounters throughout lifetime

includes electronic medical record (EMR)

radiology information system (RIS)

system specific to radiology

what does clinical informatics involve

data management for radiologic services both within and outside the healthcare system

what is accurate PHI critical to

healthcare revenue streams and financial stability

what guidelines does PHI require proficiency with

ICD-10-CM

current procedural terminology, 4th edition (CPT-4)

what is medical image management and processing system (MIMPS)

sophisticated computer network designed for digital imaging departments and enterprises

formerly PACS

what does MIMPS deal with

acquisition

distribution

storage

display

what kind of information is MIMPS permitted to share

healthcare specific not vendor specific

• integrating the healthcare enterprises (IHE)

what are platforms that chare medical image and information across modalities and platforms

health level seven standard (HL7)

DICOM

what will growth of VNA’s create

health information exchanges (HIEs)

what does DICOM header on digital images include

accession number

patient name and identification number

date and time of examination

radiographic procedure

total number of images in study

exposure related information: kVp, mAs, exposure indicator, pre or post processing

what does DICOM worklist do

assist radiographer in maintaining accuracy of information

what is grayscale standard display function (GSDF) for

consistently displaying characteristics such as grayscale appearance and image quality