PACS Fundamentals & Workflow in Radiology 4th Topic (continuation of PACS- 2nd topic)

4th Topic (continuation of PACS- 2nd topic)

PACS (Picture Archiving and Communication System)

An electronic version of the radiologist reading room and the file room

PACS

Consists of a digital acquisition, display workstation & storage devices interconnected through an intricate network

First PACS

Emerged in the 1980s and generally served a single modality, specifically Ultrasound

DICOM (Digital Imaging & Communications In Medicine)

Universally accepted standard for exchanging medical images among the modality, viewing stations, and the archive

DICOM Standard (Completion)

First completed in 1985, laying the groundwork for the future development of integrated PACS

DICOM's Communication Role

Each modality & PACS communicate via DICOM, and DICOM continues to be refined every year

DICOM's Developers

Developed by the National Electrical Manufacturers Association (NEMA) and the American College of Radiology (ACR)

Why DICOM is important

ACR and NEMA saw a need for a standard method to transfer images and associated information between different vendor devices, according to the International Organization for Standardization, as these devices produce a variety of digital image formats

DICOM Standard Parts

Currently, there are 22 separate parts covering everything from DICOM's overview, definitions, data structures and encoding, media storage, media formats, security, and other important aspects of DICOM's standardization and protocols

Image Acquisition

The process where most images are acquired in a digital format, meaning they are inherently digital and can be transferred via a computer network

Display Workstations

Any computer that a healthcare worker uses to view a digital image

Archive Servers

The central part of the PACS, housing all historic and current data

Display Workstation

The most interactive part of a PACS

Display Workstation Function

Receives images from the archive or from the various radiology modalities & presents them for viewing

PACS Application Software

Allows users to perform minor image-manipulation techniques to optimize the image being viewed

Archive Servers (File Room of PACS)

Composed of a database server or image manager, short-term & long-term storage, and a computer that controls the PACS workflow (workflow manager)

Archive Servers (Central Hub)

Serves as the central hub that receives all images before they are released to the radiologists for interpretation

Workflow (General Definition)

A term that can be used in any industry or organization, simply meaning how a process is done, step by step

Workflow (in Radiology)

Used to describe how an examination is completed, from order entry to transcribed report

Display Workstation Components

Consists of a monitor, a computer with a mouse & keyboard

Monitor

The most important element of a PACS Display Station

Advantages of LCD Monitors

Include their size, lack of heat production, less maintenance, and resolution

1K Monitor

Typically used for cross-sectional images

2K Monitor

Typically used for CR/DR digital projection images

5K Monitor

Represents the highest resolution monitors available

Pixel

The basic picture element on a display

Resolution

The number of pixels contained on a display

Resolution

The process or capability of distinguishing adjacent parts

Matrix

A rectangular or square table of numbers that represents the pixel intensity to be displayed in a monitor

Common Screen Resolutions

◦ 1280 x 1024 (1K)
◦ 1600 x 1200 (2K)
◦ 2048 x 1536 (3K)
◦ 2048 x 2056 (5K)

Reading Stations

Used by radiologists

Review Stations

Used by referring physicians

Technologist Quality Work (QC) Station

Used by technologists

Reading Stations (Radiologists)

Used by radiologists when making a primary diagnosis, feature the highest quality hardware, best monitors, are robust, and have customizable keyboards & mice

Review Workstation (Referring Physician)

A step-down model of the radiologist reading workstation, using the same level of software but eliminating some of the more advanced functions

Review Workstation Advantage

Offers the ability to view current & previous reports along with the images, which is accomplished through the integration of RIS functions with the PACS software

Greatest Advantages of a PACS

The ability to view the same set of images in multiple locations at one time

Quality Control Station (Radiologic Technologist)

Used to review images after acquisition but before sending them to the radiologist, to improve or adjust image quality characteristics, and to verify patient demographic information; typically uses a 1k monitor

File Room / Image Management Stations (Before PACS)

Historically, a large open room with endless rows of shelves full of film jackets/envelopes

File Room / Image Management Stations (Today with PACS)

May be as simple as a couple of computers with CD/DVD burners & a dry laser to make copies for outside needs

File Room Workstation

Used to look up examinations for a physician or to print copies of images for the patient to take to an outside physician

Hospital Preference (File Room)

Some hospitals prefer the use of CD instead of printing films to save cost

Navigation Functions

1.1 Hanging Protocol

1.2 Study Navigation

Image Manipulation & Enhancement Functions

1. Window Level & Window Width

2. Annotations

3. Flip & Rotate

4. Pan, Zoom & Magnify

5. Measurements
   5.1 Distance & Angle Measurements

Navigation Functions

Used to move through images, series, studies, and patients

Mouse (Navigation Tool)

A useful navigation tool; the right mouse button offers many short features in a menu of frequently used tasks & applications

Hanging Protocol

Defines how a set of images will be displayed on the monitor, often showing a previous examination on one monitor and the current examination on the other

Study Navigation

Refers to the current or previous examination being viewed, which may comprise two or three single images (projection radiography) or several series of images (MRI)

Image Paging Methods

Images can be paged through using the scroll wheel (mouse), arrow keys on the keyboard, or through stacks

CINE

A stack mode of scrolling, used most often in sectional imaging

Window Width

The range of gray values that are being viewed

Window Level

Refers to the brightness of the image

Window Level & Window Width (Default Function)

Typically the default function of the left mouse, activated by depressing & holding down the mouse button and moving the mouse up and down, left & right

Annotations

Most PACS allow users to annotate text or graphics onto the image, for example, to indicate prone or supine positions, time (e.g., "30 minutes"), or plate position (e.g., "upright or flat-plate")

Annotations (Critical Note)

This function should not be used to label left or right to indicate the patient's side, as digital R & L markers will not hold up in court due to the ability to mark, flip & rotate the image

Flip & Rotate

Used to orient the image in the anatomic hanging position, making lead markers very important to ensure the correct side

Pan, Zoom & Magnify

Primarily used by radiologists to increase the size of an area on the image, with pan and zoom usually used together

Measurements

Include distance measurement, angle measurement (commonly in spine studies), and Region of Interest (ROI)

ROI (Region of Interest)

Each type of tissue/fluid has a slightly different intensity reading, and ROI is used to determine the pixel intensity of a certain area

CTR (Cardio-Thoracic Ratio)

Calculated by dividing the cardiac diameter by the thoracic diameter (normal range

Patient Demographics Modification

Most PACS allow the user to modify patient demographics

Access Control

To minimize errors, only certain people have access to change patient demographics

Query/Retrieve Function

Used to retrieve studies from the archive

Query Function

Allows the user to query a study on multiple fields such as the patient’s name or ID, date of service/exam, or modality

Reading Station Advanced Functions (under Advanced Workstation Functions)

◦ Multiplanar Reconstruction (MPR)
◦ Maximum Intensity Projection & Minimum Intensity Projection (MIP & MinIP)
◦ Volume Rendering Technique (VRT)
◦ Shaded Surface Display (SSD)

Technologist QC Station Advanced Functions

◦ Stitching
◦ Image Post-processing

Multiplanar Reconstruction (MPR)

One of the most commonly used 3D rendering techniques; Most common application is producing coronal images from the axial set to reduce radiation to the patient & to reduce scan time at the modality.

MPR (Most Common Application)

Producing coronal images from the axial set to reduce radiation to the patient & to reduce scan time at the modality

Maximum Intensity Projection (MIP)

Typically used for visualizing vessels

Minimum Intensity Projection (MinIP)

Typically used for visualizing air-filled structures

MIP (Common Use)

Commonly performed after the injection of contrast on CT & MRI studies, where the contrast will show areas of strictures & blockages within the vessels

Volume Rendering Technique (VRT)

Similar to MIP but allows the user to assign colors based on the intensity of the tissue so that bone, contrast agents, & organs can be seen in different colors, utilizing a histogram type graph to differentiate structures; The technique uses histogram type graph to differentiate the various structures.

Shaded Surface Display (SSD)

Uses a threshold of pixel intensity value; everything below the threshold will be removed, and everything above the threshold will be assigned a color and shown as a 3D object; Everything below the threshold will be removed everything above the threshold will be assigned a color and shown as a 3D object.

Stitching

Used when multiple images need to be put together into one image, commonly for full-spine x-rays, scoliosis series, or long bones (extremities); Most common application is for full-spine x-rays or a scoliosis series, long bones (extremities)

Image Post-processing

Advanced functions of the workstation, such as edge enhancement, smoothing, & contrast enhancement