CT & PET Scanners

Medical Imaging Solutions from Texas Instruments

Reference Designs


Computed tomography (CT) is a medical imaging technique that produces three-dimensional images of internal human body parts from a large series of two-dimensional X-ray images taken around a single axis of rotation. When compared with a conventional X-ray radiograph, which is an image of many planes superimposed on each other, a CT image exhibits significantly improved contrast.

With the advent of diagnostic imaging systems like CT, where complex and intensive image processing is required, semiconductors play a very important role in developing systems with increased density, flexibility and high performance.

X-ray slice data is generated using an X-ray source that rotates around the object with X-ray detectors positioned on the opposite side of the circle from the X-ray source. The whole rotating structure is called gantry and every x-ray shot from a given angle is called profile. Of the order of 1000 profiles per revolution are taken progressively as the object is gradually passed through the gantry. The data acquisition system usually consists of a number of channel cards that have an array of scintillator-photodiode solid state detectors follow by the readout electronics.

Each photodiode produces a current proportional to the x-ray intensity that the pixel receives. Traditionally, the channel card has a front-end where the current from the detector is integrated and converted to digital values by ADCs. TI’s DDC products are single-chip solutions for Directly Digitizing low-level Currents from photodiode arrays in CT scanners. Each DDC channel provides a dual switched integrator front-end to process the current coming from one photodiode. This configuration allows for continuous current integration (avoiding any input signal loss): while one integrator output is being digitized by the on board A/D converter, the other is integrating the input current.

The digital data from all channel cards is transferred by high-speed link (LVDS interface) to the controller card and onto the image conditioning cards. The image conditioning card is connected to the host computer where the CT images can be viewed. Here, the digital data are combined by the mathematical procedure known as tomographic reconstruction.

Within the controller cards, TI DSPs with advanced VelociTI™, very-long-instruction-word (VLIW) architecture developed by Texas Instruments (TI), are an excellent choice for medical imaging applications. DSPs can be used to provide accurate control of the gantry rotation, the movement of the table (up/down and in/out), tilting of the gantry for angled images, and other functions such as turning the X-ray beam on and off. Another important DSP control functionality is ECG gating used to reduce motion artifacts caused by heart movement. Here, the data acquisition is carefully synchronized with the heartbeat. For interfacing with a PC, gigabit Ethernet transceivers allow for high-speed full-duplex point-to-point data transmissions. The PCI Express™ PHY interfaces the PCI Express Media Access Layer (MAC) to a PCI Express serial link.

The CT Scanner application may have ultra-fast transient requirements for high performance DSP and/or FPGAs, where TI’s high-performance non-isolated power modules are well suited. If high PSRR, fast start-up, and low noise are concerns, low-dropout (LDO) linear regulators are available. TI’s portfolio includes voltage supervisors, DC/DC converters, power modules, and LDOs that allows complete flexibility for the user to configure a power solution that meets the sequencing requirements for the system.

Recommended Resources

Medical Imaging Brochure

Medical Imaging Brief
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Application Notes (6)

Title Abstract Type Size (KB) Date Views
HTM 8 KB 29 Aug 2012 2170
HTM 8 KB 09 Oct 2011 11206
HTM 9 KB 08 Jun 2010 204
HTM 8 KB 08 Jun 2010 109
HTM 9 KB 21 Sep 2009 2159
HTM 9 KB 25 Mar 2008 89

User Guides (1)

Title Abstract Type Size (KB) Date Views
htm 8 KB 09 Sep 2008 156

Selection and Solution Guides

Selection Guides (2)

Title Abstract Type Size (KB) Date Views
PDF 9.09 MB 02 May 2013 3517
PDF 2.38 MB 08 Jun 2010 971

Solution Guides (1)

Title Abstract Type Size (KB) Date Views
PDF 2.3 MB 20 Nov 2015 38369

Product Bulletin & White Papers

Product Bulletin (2)

Title Abstract Type Size (MB) Date Views
PDF 228 KB 09 Jun 2011 535
PDF 208 KB 25 Apr 2011 983

White Papers (14)

Title Abstract Type Size (MB) Date Views
PDF 914 KB 23 Feb 2012 370
PDF 1014 KB 17 May 2011 802
PDF 562 KB 21 Dec 2010 598
PDF 423 KB 09 Nov 2010 1481
PDF 5.27 MB 20 Jun 2010 204
PDF 333 KB 08 Jun 2010 360
PDF 358 KB 18 Mar 2009 26
PDF 115 KB 03 Nov 2008 1017
PDF 187 KB 31 Oct 2008 484
PDF 80 KB 17 Jul 2007 174
PDF 66 KB 24 Aug 2004 2549
PDF 107 KB 07 Jan 2004 376
PDF 70 KB 01 May 2003 9
PDF 89 KB 01 May 2003 2

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