Ch 17 Viewing the Medical Images & Ch 18 Picture Archiving and Communication System

Human Eyes can see…?

bright light easier than dim light

Eye Cones see

bright light

Eye Rods see

dim light

Lumen

basic unit of Photometry

Luminous Flux

the total intensity of light from a source

Illuminance

The intensity of light incident on a surface

Luminance Intensity

Luminous flux emitted into the entire viewing area

Luminance

Similar to luminance intensity

Cosine law and Luminous Intensity

decrease in proportion to the inverse square law

(the same amount of light photons but spread out, they lose intensity when viewing the monitor)

Cosine Law: when monitor is viewed straight

the luminous intensity is greatest

Cosine Law: when viewed from an angle

Contrast and luminous intensity are reduced

Hard Copy

film on a view box

Soft Copy

digital images read from a monitor; LCD or LED. No longer CRT

LCD stands for

Liquid Crystal Display

LCD has

properties of a solid (crystal) and a fluid

LCD are

electrically charged forming a natural molecular dipole ( + & - )

LCD Crystals can be

aligned by an electrical field

Display Characteristic color LCD have

Red, Blue, Green filters built into each pixel

Medical LCDs are

MONOCHROME devices

how is the backlight of the LCD display?

(fluorescent or LED) illuminates all pixel and is blocked or transmitted by the orientation of the liquid crystals

How much backlight is transmitted through monochrome monitor?

10%

What happens to some light?

absorbed in filters and polarizers; blocked by the TFT and bus lines

LCD have what ability?

to control each pixel individuality

LCDs have better

gray-scale definition and better contrast resolution than CRTs

LCDs do not have

glare or reflection; have less noise

how does Crosstalk occur?

when photons falling on one pixel are “falsely” sensed by other pixels around it.

(Crosstalk in the context of LCD (Liquid Crystal Display) monitors used in radiology refers to a visual defect where the luminance (brightness) of a pixel can be affected by the luminance of neighboring or surrounding pixels)

(the phenomenon where light or signals intended for one pixel on an image sensor are unintentionally detected by neighboring pixels)

LED stands for?

Light Emitting Diode

LED diode allows electrical current to flow…

in one direction

LED light is

the backlight for LCD display

LED displays are thicker or thinner?

thinner

LEDs have __________________ for the visual screen?

large active area

LED displays have _____________ than fluorescent lights

longer life

What is Ambient Light?

the light around us

AMLCD’s (Active Martrix Liquid Crystal Display) reduce

the effect of ambient light on image contrast

Ambient light level should be

near darkness

What is the ergonomic design of reading workstation?

Perpendicular Viewing

With Preprocessing the Digital image, it automatically manipulates

the image before display

Preprocessing is designed to produce?

artifact-free images

Flatfielding

helps to correct the heel effect, given a more even image

Flatfielding makes the

response of the image receptor uniform

Signal Interpolation

a dead or defective pixels value is averaged from surrounding

(when a pixel is bad, the pixels around can carry the load and still provide an image)

Postprocessing is

anything done to a digital image after it is acquired

Why is POSTprocessing done?

to optimize appearance of image to better detect pathology

Annotation

adding text

window and level

contrast and brightness

image inversion

black to white, white to black

DSA

Digital Subtraction Angiography (ex: remove bone to see blood vessels)

Pixel Shift

corrects misregistration

ROI

quantitive radiology - measured density of pathology

Edge Enhancement is for

small fractured and small, high contrast tissues

highlighting is for

diffuse, non-focal disease

(DIFUSSE - SPREAD OVER AN AREA; NON-FOCAL NOT SPECIFIC TO)

pan, scroll, zoom

to see precise regions of an image

Chapter 18

Name Four Principles for PACS *

IDSN;

Image acquisition System - WHERE xrays are taken (portable, rad room)

Display System - where image is viewed

Network - connects everything together between computers

Storage - archiving part of PACS

aka I Do Need Sushi

What does the Network do?

Connects each client (image system and workstation) to Central Computer

Teleradiology is?

remote transmission and viewing of images

*TELE because they used to use telephone lines

DICOM

Digital Image and COmunnication in Medicine

What does DICOM ensure?

adaptability between different imaging systems - national standard for image transmission in teleradiology

Network begins with imaging system -

acquired and processes images, transmits to PACS

What does DICOM contain?

contains metadata that provide information about the image data

What is involved in Metadata?*

• size,

• dimension's,

• bit depth,

• modality used to create the data

• equipment settings used to capture the image

Where can images be transferred?

images can be transferred to other clients within or outside the hospital

What is necessary to have regarding Network?

fast computers and high-band with networks necessary

RIS stands for?

Radiology Information System

What is subcategory to RIS

PACS

MIMPS

What is RIS?

information management and database system for radiology department - stores imaging patient info, reports, accounting..

What can secretarial workstations do?

generate reports, schedule pt, copy images

List the devices/clients that are interconnected in a radiology network *

• imaging system,

• hospital mainframe,

• workstations,

• radiologist computer,

• web server,

• archive server,

• web clients

What does PACS prevent?

prevents lost images

What was film and file room replaced by

a magnetic or optical memory device

EMR stands for?

Electronic Medical Record

HIS stands for

Hospital Information System