Data Acquisition System (DAS) + Computer System

What are the most important characteristics of CT computer systems.

Fast and efficient data processing and extremely large data storage capacity

Why must the ADC must be enormously sensitive to a vast range of signal intensities.

The vast range of tissue densities inherent in CT imaging results in extremely small fluctuations in attenuation

Common types of OS software include

Windows, MS-DOS, OS/2, and UNIX

Beam collimation to 5 mm on this system would result in the possible reconstruction of four

a. 1.25-mm-thick images for every gantry rotation. (FIG 5.11C PG103)

Pipelining is

an additional feature of CT computer systems that further improves the speed and efficiency with which it can perform multiple simultaneous functions, including detector signal preprocessing, convolution, postprocessing, and image manipulation.

The primary data processing component of the CT system is the

array processor. A separate computer with its own CPU

Because only four z-axis data channels are available, the signal from four detectors may be What to form images that are 5 mm thick (4 x 1.25 mm = 5.0 mm)

be combined, or binned

If the beam is further collimated to 10 mm, the transmitted radiation exposes only the

center 10 mm of the detector array, corresponding to the middle eight detectors out of the total of 16 (8 x 1.25mm = 10mm)

The analog-to-digital converter (ADC) is the

component of the DASS responsible for converting the electronic signal into digital form. This digital data are then transmitted to the system computer for image reconstruction.

The DAS consists of

electronic components responsible for measuring the transmitted x-radiation absorbed by the detectors

Electronic amplifiers condition and boost the

electronic signal that the detectors transmit in response to radiation absorption

the array processor is connected to the

main host computer of the CT system

The operating system (OS) is the

main software of the CT computer

Postprocessing software does what

manipulates the image data for review and interpretation. This software controls the image visualization and analysis tools of the CT system, including applications such as windowing, image display filters, 3-D/MPR reformation, and analytic functions (ROI, distance).

The hard disk drive is the common choice for

mass storage of CT computer system data

Reconstruction software is responsible for

mathematically constructing the raw data into image data using algorithms for the processes of convolution, back projection, data frequency filtering, and so on.

If the beam is further collimated to 10 mm, the transmitted radiation exposes only the center 10 mm of the detector array, corresponding to which detectors that measure 1.25mm out of the 16 detectors it has

middle eight detectors out of the total of 16 (8 x 1.25mm = 10mm)

With the use of combined or binned images with beam collimation of 20 mm, this system is capable of producing four CT images per gantry rotation with a minimum thickness of What with each detector measuring 1.25mm

minimum thickness of 5 mm (4 x 1.25 mm = 5.0 mm) (4*5=20)

The central processing unit (CPU) is capable

of performing multiple tasks simultaneously, a function called parallel processing.

What is parallel processing

performing multiple tasks simultaneously

When the beam collimation is set to 20 mm, all detectors measure transmitted radiation and produce

proportional signal to be collected by the DAS.

The array processor is responsible for

receiving scan data form the host computer, preforming all of the major processing of the CT image, and returning the reconstructed image to the storage memory of the host computer

The hard disk drive is a

rewritable, nonremovable storage system the must be capable of storing a tremendous amount of data. It also must be able to transfer data quickly, in a manner quantified by the data transfer rate.

Preprocessing software processes the

signal data collected from the detectors and conditions it by applying appropriate correction factors for beam hardening, detector malfunction, and so on.

The DAS of a MDCT system has a maximum number of data channels used to transmit data from

the detectors to the computer system for image reconstruction.

The number of data channels controls

the number of slices the system can acquire with each gantry rotation.

During MDCT, the DAS is responsible for controlling

the signal emitted from the activated detectors exposed to the collimated x-ray beam.

The operating system (OS) is the main software of the CT computer. It controls the

utilization of the hardware resources, such as the available memory, CPU time, and disk space.

The four channels are now capable of producing four CT sections per gantry rotation, each How Many mm in thickness and representing the combined data from two detectors

2.5mm (2x 1.25 mm = 2.5 mm)

if the detector array contains 16 detectors with each measuring 1.25mm along the z-axis what is the mm total

20mm total

the DAS of a four channel MDCT system has how many z-axis data channels

4