:: dicom medical image transfer

The development of medical imaging over the past 10 or so years has seen a huge increase in the role of digital techniques and applications. CT is an intrinsically digital modality, and has always had to find a way to store its images electronically.

ImPACT has been assessing the imaging performance of CT scanners for many years, and without an effective method of image transfer all of the image analysis would have to be performed at the assessment site. Our custom written image analysis software enables us to perform our assessments in a consistent and repeatable manner.

A collection of just some of our archive devices

Over the years, we have built up a wide range of storage devices to ensure compatability with the different scanner manufacturers' chosen archive format. As well as this, every time we looked at a new scanner, the file format seemed to have changed, so a new image reformatting progam would have to be written - often this was not a trivial task.

When DICOM facilities started to become available on all new CT scanners, we saw an opportunity to standardise our approach to data transfer. Using a laptop Sun workstation and the appropriate DICOM software, we could transfer the images that we had acquired quickly and easily at the end of an assessment.

DICOM is a standard that has evolved over the years from a system for communicating between CT scanners produced by different manufacturers to a greatly more wide ranging multi-modality communications facility. It features a common file format and the facilities for standardised network send, receive and query. It also supports patient management, network printing standard image archiving and is designed to integrate with HIS/RIS systems.

The RSNA has always been heavily involved in DICOM, and its DICOM information page is a good place to start for general information. Our DICOM software was obtained (free of charge!) from the University of Oldenberg, Germany. This can be compiled on a wide variety of computer platforms, including Sun workstations, PCs running Windows 95/NT or Linux. A ready compiled version for Win 95/NT is also available. A general medical image viewer, with DICOM capabilities, Osiris, is available from the University Hospital of Geneva. David Clunie's Medical Image Format pages are another mine of useful information for people trying to get to grips with, and convert medical images.

It must be said that DICOM can be a fairly technical subject - all of the documenation is steeped in jargon. A working knowledge of computer networks and protocols is very useful. Having said that, though, we have managed to get DICOM to work for us on a practical basis. This has not always been easy, as there usually seems to be some small piece of vital information that is needed to get our fairly simple image transfer working. In many ways, the way we use DICOM is not typical, as we are only connecting to each machine once, and then moving on to a different unit, with different potential difficulties.

Getting to the root of a DICOM communication problem

Overall, our experience of DICOM has been that it is a useful manufacturer independent method for transferring CT images for analysis, but that it is not without its technical difficulties. It has made our assessments easier, and reduced the need to write separate image conversion software.

There is a 'how to' article on transferring medical images to a PC using DICOM here.