Picture archiving and communication systems (PACS)

Published on 12/06/2015 by admin

Last modified 22/04/2025

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10 Picture Archiving and Communication Systems (PACS)

PACS is a method of storing images in a digital format. Once stored they can be sent to different parts of the hospital and to the wider medical community. Many manufacturers produce systems to enable the transfer of information and the systems they produce contain some or all of the following:

Terminology

Image Identification	• Either a barcode reader or a touch screen for patient identification • Either a barcode reader or a touch screen for cassette identification
Image Identification	This can either be: • Downloaded from the central hospital computer or appropriate imaging modality • Keyed in using the computer keyboard or • Directly read from a bar code.
Reporting Consoles (Reporting consoles allow instant access to diagnostic images, allowing the decision to be taken immediately as to whether or not additional projections will be required before the patient leaves the department. In addition, current and archived images and previous reports can be displayed alongside each other to give a full clinical picture of the patient’s condition prior to reporting)	It is possible to change the image presentation on the monitor with regard to: • Viewing several images together • Viewing an animated sequence of images • Tonal conversion which is the selection of the appropriate contrast and density for the anatomical region under investigation • Spatial frequency modification which allows the selective manipulation of an image to eliminate ‘blurring’ or contrast disparity • Edge enhancement as the name suggests, more clearly defines the outline of various bones or organs • Magnification allows different parts of the image to be magnified although some systems do not allow the magnified image to be recorded on film • Measurement, rotation and image reversal are all possible and in some instances, the operator is able to manipulate the image to produce three dimensional images providing the appropriate software and images are present • Sound reporting is the means of dictating and then saving an oral report by using a telephone headset. The recording can then be digitised and stored with the appropriate image. The recording can then be archived, transmitted or replayed at a later date
Remote Consoles	• Viewing stations to retrieve images from the intranet for internal staff • Viewing stations to retrieve information from the internet for external staff • The consoles can be sited throughout the hospital in intensive care units, theatres, accident and emergency departments, teaching units, etc. • The images can be displayed alongside the reports and additional information, e.g. exposure factors, can also be displayed • The use of these consoles can save time as the manual retrieving, transporting and copying of films is no longer required
Central Storage	• A Web server with a database to store the image With automatic deletion after the patient leaves hospital • A Web browser For the selection of information by patient name For the selection of images of a specific patient • Storage in a DICOM format Allows universal connections to imagers, workstations and external users Using either RAID (Redundant Array of Independent Disks) or CD-R or Digital Linear Tape (DLT) • Computerised archiving
Patient Journey	• It is possible to create a database for a patient entering the hospital • On this database can then be recorded patient information: Current history Referral letters (which may be received directly from the General Practitioner via an electronic mailing system) Test results Reports An accounting system (to enable rapid and accurate invoicing) • In addition, it is possible to have the automatic creation of statistical information For stock control Equipment ordering
Patient Journey	The patient information can remain in the system until the patient is discharged from the hospital and can then be automatically stored in the central archive • It is possible to store in the order of 2500 diagnostic images on a inch optical disk – • Or up to 15 000 images on a 12 inch optical disk – • Or images can be stored on the World Wide Web, thus saving on storage space
Information Retrieval	Can be based on: • Patient surname/forenames • Date of birth • Imaging number • Condition • Date of imaging production • Or audit value
Hard Copy Images	By networking the system to a laser printer, it is possible to select and then produce hard copies of images and reports for storage in the patient’s notes in the conventional way
Modem Links (A modem is the term used for an interface which links units via the telephone system)	It is possible to send images to other hospitals in this country or abroad
	Examples • A patient has had an accident on the continent and then has returned to this country, the images and reports could be transmitted directly to the receiving hospital • If a patient had a condition diagnosed in one hospital and required transferring to a specialist unit; again the images could be sent directly • Some installations allow direct connection to a service engineer to allow the engineer to do quality control checks or to trace and, in some instances, rectify software faults • If faults occur in the hardware, remote fault diagnosis may also be possible, enabling the engineer to order the appropriate components and coordinate the arrival of the parts and the engineer to minimise departmental down-time
Image Security	• Via passwords and defined user groups • External sources receive encoded data
Automatic Updating	Enables the system to automatically access new innovations and technology

Three dimensional imaging

With the advent of workstation systems with their associated increase in power and memory, at an affordable price, software packages have been developed which enable the production of three dimensional images which can be displayed, manipulated and thus allow measurements to take place. In a networked system, it is now possible to manipulate images at stand-alone workstations by, if necessary, downloading power to prevent system overload. Software can be used to manipulate images from ultrasound, CT, MRI, etc. to aid with, e.g. radiotherapy planning, joint replacement surgery, cosmetic surgery and tracing major vessels prior to operations. It is also possible to combine images from several modalities and, e.g. enhance the image or change its orientation

Application

Volume Measurements	• These can be in the form of quantitative analysis of a defined area, e.g. a tumour • Statistical analysis could be performed • The results can be presented graphically if required
Curved Sections	• By selecting a standard plane through the body which could be transverse, coronal or sagittal, a curved line could be drawn • This could, e.g. follow a blood vessel, and therefore its relationship with the associated structures could be identified
Volume Rendered Images	By adjusting the threshold values of an image, either the soft tissue, bone structure or internal organs can be displayed from the same original image
Image Enhancement	This could be used to manipulate an under-exposed image to make it diagnostically acceptable. There is therefore the potential for reducing the initial patient dosage, and by reading, and then manipulating the image from an imaging plate, producing a diagnostic image
Image Analysis	It is now possible to undertake computer analysis of X-ray film images. Some examples of how this technology is being utilised are:
Pronosco X-posure System™ (This is a method of assessing bone mineral density)	• The hand, wrist and forearm are radiographed • The radiograph is digitised using a scanner system • The radius, ulna and three middle metacarpal bones are automatically analysed for porosity and striation • A printout of the bone mineral density estimate is produced
ImageChecker™ (To aid with the screening of routine mammograms)	• The mammograms are taken • The films are placed in an image checker processor which contains a barcode reader, a laser film digitiser and a computer to process the images • The image is digitised • The image is automatically analysed to show regions of interest • Cluster white areas are marked • Dense areas with radiating lines are marked • The original films are reported on in the normal way • The display unit is then activated and the marked images are displayed • The radiologist then reviews the original films in the light of the additional information