Digital Image Display, Assessment, and PACS

Radiographic Exposure

HIS (Hospital Information System)

Contains patient medical records (EMR) & sends radiology orders to RIS

RIS (Radiology Information System)

Creates worklist and merges patient data with radiology exam fields

PACS stands for:

Picture Archiving and Communication System

PACS is a computer system used to _____, _____, and _____ images from digital modalities.

acquire

display

transmit and score

Functions of PACS (3 things):

1. integrates medical record on HIS with RIS

2. displays acquired images through hospital network

3. allows images to be accessed over the internet

Exposure indicator is what and indicates what?

A number indicating the average radiation exposure to the IR in order to form a CR image.

May indicate under or over-exposure.

DICOM stands for what?

Digital Imaging and Communication in Medicine

What is DICOM?

A STANDARD that establishes RULES for the exchange, display, and storage of medicine images and text.

RAID stands for what?

redundant array of independent disks

What is RAID?

A group of hard disks that provides data protection and improves data acquisition speed.

minimum scale bit depth for dicom

2.5 mm/lp

What is Moire Pattern?

Appearance of grid lines caused by the scan frequency and direction matching that of grid.

Exposure number means? — what +3 or -3 means — and what to do with kvp and mas

DQE stands for what?

Detective Quantum Efficiency

What is DQE?

The ability of a detector to convert x-ray to a useable signal based on measurement of the combined effects of CONTRAST and NOISE on the imaging system.

DQE values will always range from:

0 to 1

Advantages of CRT monitor (2 things):

1. Less expensive than LCD

2. Can see image at sharp angles to monitor

Disadvantages of CRT (4 things):

1. blooming

2. soft copy veil glare

3. glare

4. luminance

Advantages of LCD (Liquid Crystal Display) 6 advantages:

1. higher luminance than CRT’s

2. produce less heat

3. no veil glare

4. less reflection glare

5. less maintenance

6. less power consumption

Disadvantages of LCD (2 disadvantages):

1. more expensive than CRT’s

2. limited field of view from extreme angles

Dynamic range — how its read out

Gray scale bit depth

What is dynamic range?

the number of shades of gray that can be displayed on an imaging system.

More on dynamic range (2 things):

1. response is linear

2. all digital images have a wide dynamic range

How much file storage space is needed for DR images if there are 10 images and the matrix size is 1,000 X 1,000 with a 12 bit depth?

1,000 X 1,000 = 1,000,000

1, 000,000 X 12/8 = 1,500,000

1,500,000 X 10 images = 15 Mb

ACR requires a minimum spatial resolution of at least:

2. 5 lp/mm

What is KERMA?

Kinetic energy released in matter is used to express radiation concentration delivered to a point by radiographic and fluoroscopic equipment.

KERMA is formally defined by the amount of energy released per kilogram of _____ in _____.

air
Gy_a

When KERMA is written to express absorbed dose in _____ it is denoted as _____.

tissue
Gy_t

What is KAP?

Kerma Area Product

____ is defined as contrast seen in the image divided by the amount of noise existing in the image

CNR (contrast-noise ratio)

Where should the IR plate be read out?

The middle — center points

Three types of monitors:

1. Consumer grade monitors

2. Medical displays

3. View boxes

Consumer grade monitor range:

250 — 300  (cd/m²)

Medical displays

300 — 500 (cd/m²) or 170 nits

Viewboxes: low intensity, high tensity, and average

Low: 1000 — 2000 nits

High: 2000 — 3000 nits

Avg: 1700 nits

What is HL7 (Health Level - 7)?

An international organization that develops standards related to exchanging information between medical applications.

What does HL7 aim to improve?

“interoperability” of healthcare information along with improving workflow, decrease ambiguity and share information between providers of healthcare

Lossless compression ( 2 things):

No loss of image fidelity between original and decoded image

Typically 2:1 or 3:1 compression

Lossley compression

Higher compression that may lose image detail after being decoded