PACS FINAL 1ST WEEK A

Picture Archiving and Communication System (PACS)

PACS consists of digital acquisition, display workstations, and storage devices interconnected through an intricate network.

PACS Function

The PACS is an electronic version of the radiologist reading room and the file room.

PACS in Hospitals

The picture archiving and communication system (PACS) is becoming more commonplace in today's hospitals because administrators see its necessity for serving physicians and patients, even though it is expensive.

Digital Imaging and Communications in Medicine (DICOM)

Digital imaging and communications in medicine (DICOM) is a universally accepted standard for exchanging medical images among the modality, viewing stations, and the archive.

DICOM History

First completed in 1985, this standard laid the groundwork for the future development of integrated PACSs.

DICOM Communication

Each modality and PACS communicates via DICOM, and DICOM continues to be refined every year.

PACS - 3 Fundamental Parts

Image acquisition, display workstations, and archive servers.

Image Acquisition (Modern Radiology)

In modern radiology departments, most images are acquired in a digital format, meaning that the images are inherently digital and can be transferred via a computer network.

First PACS Modality

The first PACS served a single modality—namely, ultrasound.

Ultrasound Mini-PACS

Ultrasound mini-PACS networks were the norm in many hospitals.

Softcopy Reporting Development

It was a natural step to convert ultrasound to softcopy reporting (reading images on the computer without hard copy films).

Display Workstation Definition

A display workstation is any computer that a healthcare worker uses to view a digital image.

Display Workstation Function

It is the most interactive part of a PACS, and these workstations are used inside and outside of radiology.

Display Station Image Source

The display station receives images from the archive or from the various radiology modalities and presents them for viewing.

PACS Application Software

The display workstation has PACS application software that allows the user to perform minor image-manipulation techniques to optimize the image being viewed.

Archive Server Definition

An archive server is the file room of the PACS.

Archive Server Components

It is composed of a database server or image manager, short-term and long-term storage, and a computer that controls the PACS workflow (workflow manager).

Archive Server Role

The archive is the central part of the PACS and houses all of the historic data along with the current data being generated.

Archive as Central Hub

In many institutions, the archive serves as the central hub that receives all images before they are released to radiologists for interpretation.

Workflow Definition

Workflow is a term used in any industry or organization; it means how a process is done step by step.

Workflow in Radiology

In radiology, workflow describes how an examination is completed, from order entry to transcribed report.

Film-Based Workflow (Department Design)

Most departments were designed years ago for film and chemical processing. Pass boxes were built into walls that fed into dark rooms and into large open reading rooms with large multiviewer lightboxes lining the walls.

First Step in Film-Based Workflow

The first step in any radiology department workflow is the entry of the order.

Order Entry Process

An order is placed in the radiology information system (RIS), and a requisition is generated.

Requisition Contents - Patient's Name

A requisition generally contains the patient's name.

Requisition Contents - Patient ID Number

A requisition contains the patient's hospital identification (ID) number.

Requisition Contents - Date of Birth

A requisition contains the patient's date of birth.

Requisition Contents - Ordering Physician

A requisition contains the ordering physician's name.

Requisition Contents - Exam Ordered

A requisition contains the examination ordered.

Requisition Contents - Reason for Exam

A requisition contains the reason for examination.

Requisition Contents - Chief Complaint

A requisition contains the patient's chief complaint.

Film-Based Workflow - Requisition to Technologist

The paper requisition is passed on to the technologist who will be performing the examination.

Film-Based Workflow - Room Preparation

The technologist prepares the room for the patient and brings the patient back to the room.

Film-Based Workflow - Verification & History

The technologist verifies all of the patient's information and completes a patient history.

Film-Based Workflow - Copies Inquiry

The technologist inquires whether the patient needs a complete set of copies to take to the next doctor's appointment.

Film-Based Workflow - Performing Exam

The technologist performs the examination and processes all of the film after the complete examination is done.

Film-Based Workflow - Film Critique

The technologist critiques each film and repeats exposures as necessary.

Film-Based Workflow - Making Copies

The technologist makes copies if necessary and releases the patient with the copies.

Film-Based Workflow - Film Jacket Arrival

The film jacket arrives hours or even days later, and the current films are hung on a multiviewer lightbox to be read by a radiologist.

Film-Based Workflow - Historic Images

The file room clerk may hang a set of historic images from the film jacket for comparison.

Film-Based Workflow - Radiologist Dictation

The radiologist reads the films and dictates a report into the dictation system.

Film-Based Workflow - Clearing the Lightbox

The multiviewer lightbox is cleared of read films by the file room clerk, and the films are placed back into the film jacket, which is then filed in the file room.

Film-Based Workflow - Transcription

A transcriptionist retrieves the recorded dictation and transcribes a report into the RIS; this may occur later that day or the next day.

Film-Based Workflow - Radiologist Final Report

The radiologist reviews the report, makes corrections, and signs it as final.

Film-Based Workflow - Report Distribution

The final report is printed and placed in the patient's film jacket along with any previous reports, and sent to the ordering physician, sometimes several days after the exam.

Generic PACS Workflow - Order Entry Status

Changes in order entry are coming, but for now the process remains the same as in film-based departments.

Generic PACS Workflow - Requisition Use

The technologist still needs a requisition to verify the patient ID and to take a patient history.

Generic PACS Workflow - RIS to PACS Messaging

The order is input into the RIS, and the RIS sends a message to PACS to find all historic images and put them on the short-term archive.

Generic PACS Workflow - Benefit of RIS-PACS Sync

This process eliminates waiting for the file room to retrieve a film jacket from an off-site storage location.

Generic PACS Workflow - Room & Patient Preparation

The technologist prepares the room, retrieves the patient, and performs the patient history.

Generic PACS Workflow - History Recording

The history is recorded on the paper requisition or input electronically into the patient's computerized medical record.

Generic PACS Workflow - Performing Exam

The technologist performs the examination, and depending on the image acquisition device, the images are processed and repeated as necessary.

Generic PACS Workflow - Sending Images

Images are sent to the appropriate PACS device.

Generic PACS Workflow - RIS Tagging

The patient images have been tagged with information from the RIS so that historic image reports are available at the PACS when the new images are sent.

Generic PACS Workflow - CD/DVD Option

If the patient's physician does not have access to the electronic images, a CD or DVD can be made that contains the images in digital format.

Generic PACS Workflow - Requisition to Radiologist

The requisition is taken to the radiologist, or the radiologist may pull the images from an electronic worklist.

Generic PACS Workflow - Comparing Studies

The radiologist pulls up historic images and reports and compares the previous images with the current images.

Generic PACS Workflow - Dictation Methods

The radiologist dictates a report and has it transcribed, or voice recognition software may be used.

Generic PACS Workflow - Voice Recognition Advantage

If voice recognition is used, the radiologist can review the report immediately after dictation, make corrections, and sign it as final.

System Architecture - Definition

System architecture refers to the hardware and software infrastructure of a computer system, including acquisition devices, storage, display workstations, and an image management system.

PACS Architectures - Three Types

Three common PACS architectures are: Client/Server-Based Systems, Distributed Systems, and Web-Based Systems.

Client/Server System - Definition

In a client/server-based system, images are sent directly to the archive server after acquisition and are centrally located.

Client/Server System - Display Workstation

The display workstation functions as a client of the archive server and accesses images from a centralized worklist generated at the archive.

Client/Server - Workflow

The healthcare worker selects a name from the central list, and the archive server sends the image data to the workstation; after viewing, the data are flushed from memory.

Client/Server Advantage - Universal Availability

Any examination sent to the PACS is available anywhere without additional intervention.

Client/Server Advantage - Single Reader Lock

Only one person can open the study with the intent to read it; others receive a message that the study is already being read.

Client/Server Advantage - Historic Image Access

There is no need to pull or send historic images because old studies are available with the new ones on the archive.

Client/Server Disadvantage - Archive Failure

The archive server is a single point of failure—if it goes down, the entire system is down and images cannot move.

Client/Server Disadvantage - Image Backlog

Newly acquired images must remain at the modality until the archive is functioning again.

Client/Server Disadvantage - Network Dependency

The system is highly network-dependent; heavy data transfer between archive and workstations can bog down the network.

Distributed System - Definition

In a distributed system, acquisition modalities send images to a designated reading workstation and possibly to review stations depending on where the order originated.

Distributed System - Example Locations

Reading and review stations may include the intensive care unit or the emergency room.

Distributed System - Alternative Workflow

In some systems, images are sent from the modality to the archive server, which then distributes the images to designated workstations.

Distributed System - Query/Retrieve

Workstations can query and retrieve images from the archive in a distributed model.

Distributed System - Local Storage

All images are stored locally on the workstation and later sent to the archive server after being read.

Distributed System - Local Retention

Images remain on the local hard drive until deleted by the user or automatically removed based on system rules.

SYSTEM ARCHITECTURE - Distributed Systems (Advantage 1)

If the archive server goes down, local reading at the workstations is not interrupted, except for not being able to get historic images. After the archive comes back up, the images that have been changed and signed off by the radiologist will be forwarded automatically to the archive to be saved.

SYSTEM ARCHITECTURE - Distributed Systems (Advantage 2)

Because the images can be distributed to many locations at once, copies of an examination exist at various locations. Therefore, it is less likely that PACS data will be lost.

SYSTEM ARCHITECTURE - Distributed Systems (Advantage 3)

The system is less dependent on the network for its speed. The user can work on one examination while the workstation pulls and prepares the next examination to be read. The workstation can fetch historic images according to rules the user sets up.

SYSTEM ARCHITECTURE - Distributed Systems (Disadvantage 1)

There is heavy reliance on the assumption that the distribution of images is being done correctly. If the distribution is wrong, the prefetching of historic examinations will not be correct.

SYSTEM ARCHITECTURE - Distributed Systems (Disadvantage 2)

Each workstation has a different worklist, and therefore only one person can be working on that list at a time.

SYSTEM ARCHITECTURE - Distributed Systems (Disadvantage 3)

It can be inconvenient to read additional studies because the radiologist would have to move to another workstation to read the images designated for that workstation.

SYSTEM ARCHITECTURE - Distributed Systems (Disadvantage 4)

The users must depend on the query-and-retrieve function when non-scheduled examinations arrive at the workstation to be read.

SYSTEM ARCHITECTURE - Web-Based Systems (Definition)

A web-based system is very similar to a client/server system in how data flow.

SYSTEM ARCHITECTURE - Web-Based Systems (How Images Are Viewed)

When someone wants to view images from a web-based application, he or she searches for the pertinent images, and the web browser displays the images held on the web server.

SYSTEM ARCHITECTURE - Web-Based Systems (Advantage 1)

The hardware at the client can be anything that supports an appropriate web browser. This allows greater hardware flexibility, though image displays may not support diagnostic quality.

SYSTEM ARCHITECTURE - Web-Based Systems (Advantage 2)

The same application can be used on site and at home in teleradiology situations. Teleradiology refers to reading images from outside the hospital, whether nearby or across the world.

SYSTEM ARCHITECTURE - Web-Based Systems (Disadvantage 1)

The system's functionality may be limited because the software is not installed locally. Network bandwidth limits the amount of data transmitted, and some programs are too large to be downloaded easily.

SYSTEM ARCHITECTURE - Web-Based Systems (Disadvantage 2)

As with client/server systems, the network is the biggest obstacle to performance in web-based systems.

DISPLAY WORKSTATIONS (Definition)

The display workstation is the most interactive part of a PACS, consisting of a monitor and a computer with a mouse and keyboard. Each system includes hardware and software tailored to user requirements.

DISPLAY WORKSTATIONS (Monitor Importance)

The monitor is one of the most important elements of a PACS display station. The liquid crystal display (LCD) is the most popular type of monitor used in radiology, with the cathode ray tube (CRT) becoming obsolete.

DISPLAY WORKSTATIONS - LCD Market Dominance

The LCD has decreased in price and increased in quality and has taken over the entire PACS display market because of its size, resolution, and lack of heat production.

DISPLAY WORKSTATIONS - LCD Advantages

The LCD requires less maintenance, gives out more light, and can be used in areas with a high amount of ambient light.

DISPLAY WORKSTATIONS - Monitor Selection Factors

Along with the number of monitors used, the resolution and orientation of the monitor are factors in determining which type of monitor to buy for each workstation. Most cross-sectional imaging is read on a 1K square monitor, and most digital projection images are read on at least a 2K portrait monitor.

DISPLAY WORKSTATIONS - Definition of Resolution

The number of pixels contained on a display is known as its resolution. The more pixels in an image, the higher the resolution and the more information that can be displayed.

DISPLAY WORKSTATIONS - Resolution Description

Resolution is the process or capability of distinguishing between individual parts of an image that are adjacent. Pixels are arranged in a matrix, which is a rectangular or square table of numbers that represents pixel intensity on the monitor.

DISPLAY WORKSTATIONS - Common Monitor Resolutions

Common screen resolutions found on today's monitors are 1280 × 1024 (1K), 1600 × 1200 (2K), 2048 × 1536 (3K), and 2048 × 2560 (5K).

DISPLAY WORKSTATIONS - Categories of Display Stations

Display stations can be categorized by their primary use: Radiologist Reading Stations, Physician Review Stations, Technologist Quality Control Stations, and File Room/Image Management Stations.

Radiologist Reading Stations - Definition

The radiologist reading station is used by a radiologist when making a primary diagnosis. It has the highest quality hardware, including the best monitor.

Radiologist Reading Stations - Hardware

The computer hardware meets the needs of the PACS vendor and is usually very robust, requiring little downtime. The keyboard and mouse can be customized.