Week 8 - PACS

These flashcards cover key concepts and terminology related to PACS, image compression, spatial resolution, and noise, providing a comprehensive review for exam preparation.

What does DICOM stand for?

Digital Imaging and Communications in Medicine.

What is the main function of HL-7?

Enables communication between hospital systems (HIS/RIS).

List 4 core PACS components.

Acquisition system, Display system, Network, Storage.

Why use DICOM worklists?

Auto-populate patient demographics → reduce entry errors.

What is the goal of IHE?

Ensure seamless data transfer and standardization across medical IT.

What are the two types of image compression?

Lossless (no data loss) and Lossy (data loss for smaller files).

What are the typical compression ratios in general radiography versus mammography?

3:1 for general radiography and 1:1 for mammography.

Give two reasons for printing digital images.

Court evidence and OR backup when PACS is unavailable.

Who maintains PACS systems?

PACS Administrator (technologist or IT staff).

Define lossy compression.

Data are discarded so image quality is irreversibly reduced, though file is smaller.

Define spatial resolution.

Ability to distinguish two adjacent high-contrast objects as separate.

What is the unit for spatial resolution?

Line pairs per millimetre (lp/mm).

What is the main digital determinant of spatial resolution?

Pixel size (smaller = better).

If Nₐᵥₑ = 1000 photons/pixel, what is the noise percentage?

Approximately 3.2%.

How can quantum noise be reduced without increasing dose?

Use a smaller matrix (fewer pixels).

What is the formula for noise percentage?

(1 / √Nₐᵥₑ) × 100.

What happens to noise if pixel count increases but total x-rays stay the same?

Noise increases because there are fewer photons per pixel.

Define contrast resolution.

Ability to differentiate low-contrast objects of different grey levels.

What does dynamic range refer to?

Number of grey levels (detector bit depth).

Explain the contrast-detail relationship.

Small objects need higher contrast to be visible; spatial and contrast resolution are interrelated.

What does PACS stand for?

Picture Archiving and Communication System.

What is the main purpose of PACS?

To digitally store, transfer, and retrieve medical images securely.

What are the three main components of PACS?

Acquisition system, display/workstation system, and storage/server system.

What is DICOM and why is it important?

Digital Imaging and Communications in Medicine; ensures interoperability between different imaging systems.

What does the RIS system do?

Stores patient demographics, exam requests, reports, and integrates with PACS.

How do technologist and radiologist monitors differ?

Radiologist monitors have higher resolution (5–32 MP) and better luminance for diagnostic accuracy.

How is patient privacy protected in PACS?

Secure login; access limited to staff directly involved in patient care; monitoring for violations.

What is required to retrieve an image from PACS?

The patient’s unique identifier, usually the Medical Record Number (MRN).

What are the benefits of PACS?

Eliminates film storage, prevents image loss, enables multi-location viewing and teleradiology.

What are some risks of PACS?

Network failures, data mismatches, potential image loss, and reduced technologist–radiologist contact.

What should be done if the wrong patient is selected from the worklist?

Submit a PACS correction form; do not delete images; notify radiologist and administrator.

What happens if the wrong patient is imaged?

A radiologist must create a new exam entry to associate images correctly; patient informed and correct exam repeated.

How can identity errors be prevented?

Use two identifiers (name and DOB) and verify the exam request.

What are the consequences of a privacy breach in PACS?

Disciplinary action, including potential termination.

Why is luminance testing important for monitors?

Ensures consistent brightness and image quality for accurate diagnoses.

Why can’t images with errors be deleted from PACS?

Because they are part of the medical record; deletion violates legal and ethical standards.

What is the biggest advantage of DICOM?

Universal image compatibility across all vendors and systems.

What is teleradiology?

Remote interpretation of medical images by radiologists using PACS.

What is one major benefit of cloud-based PACS?

Faster and easier image exchange between facilities.

What is the technologist’s medicolegal duty with PACS?

To ensure accurate patient identifiers and markers, promptly report and correct errors, and protect confidentiality.