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The technology behind medical imagery

S. Raghavendra
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DICOM is now widely used to represent information acquired through CT techniques

Specialised tools:A screenshot of Ginkgo-CADX showing the vertical and horizontal cross-sections of a human heart, reading details from DICOM data.
Specialised tools:A screenshot of Ginkgo-CADX showing the vertical and horizontal cross-sections of a human heart, reading details from DICOM data.

Medical diagnostics and related technologies have grown more sophisticated over time, but what is more complex is the technology that is required to analyse diagnostic data.

Recent advancements in electronic hardware and software have made medical imagery (using various specialised software applications) an indispensable part of the diagnostic process. While gathering or ascertaining data or information as part of diagnosis is indeed challenging, a closely related and crucial domain is that which involves the technology that helps biophysicists view, analyse and interpret this data.

The data format

But what is this technology related to medical imagery all about? Take, for instance, an image acquired from an X-ray Computed Tomography (CT) scan machine. This is similar to a picture clicked on a digital camera. But while a digital camera shows the gray scale or the colour level depth of pixels, in most cases of medical images the CT-scan information reveals the nature of tissue or the type of material within the human body, by representing the picture elements as the absorption coefficient of the incident X-rays.

This absorption information is stored in a special format that is unique to the field of medical imagery called the DICOM (Digital Imaging and Communications in Medicine) format. This format has separate data fields for patient ID, apparatus details, case history and other relevant information. Today, DICOM has become the de-facto standard in medical imagery; it is widely used to represent the information acquired using most of the CT techniques.

In a procedure called Picture Archiving and Communication System (PACS), DICOM enables transaction and sharing of information between servers, computers and the machines. DICOM format also enables information transmission over the network and supports TCP/IP.

Sabyasachi Chatterjee, a senior scientist at the Indian Institute of Astrophysics, who is currently working on an inversion problem in medical diagnosis, finds the use of computer programmes quintessential in his attempts to solve problems. “To obtain results in time and with required magnification, it is impractical today to work with classical approaches of using logarithmic tables, or even the scientific calculators. Further, computers come with the ability to run specialised programmes, allowing visualisation of information gathered which otherwise would not be possible,” he says.

Non-intrusive diagnosis

To treat a malignant tumour in the body or a blockage in the blood vessels in the heart, understanding the composition of the blocking material (plaque) is imperative.

Even until a few years ago, samples had to be taken from the patient by a separate procedure to determine the course of action. Currently, software which can understand and visualise DICOM data provides pre-emptive information, making non-intrusive (without surgery) diagnosis a reality. Using different data sets in DICOM, an elaborate understanding of a patient’s CT scan can be obtained.

Specialised tools

Most of the medical imagery tools are highly specialised and in most cases come bundled with the hardware. There are numerous programmes with abilities to interpret DICOM data with multiple modalities support.

Open Source options

Amide and Aeskulap are widely used DICOM viewers available as Free and Open Source software. Another important Open Source computer-aided diagnosis project is Ginkgo CADX, which is extensively used in analysing medical imagery when the data is in DICOM format. This tool allows researchers to qualitatively compare and deduce results from DICOM data.

Seema Rezvan, a medical physicist from Iran doing her Ph.D. at the All India Institute of Medical Sciences, New Delhi, uses Ginkgo-CADX along with a specialised Python programme. This aids her research, which involves finding the composition of plaque that causes coronary heart ailments.

“Precise diagnosis and accurate medication, both are heavily dependent on comprehensive medical imagery. Efficient treatment, now to some extent has been made non-intrusive by computers capable of running such special programmes,” she says.

  • DICOM has become the de-facto standard in medical imagery

  • Amide and Aeskulap are widely used DICOM viewers available as FOSS




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