Single-slice CT

Single-shce CT refers to a configuration where the system passes an individual, vertical, CT slice through a pre-selected region of interest in a bag. To prepare for 

The disk rotates at a uniform speed. The system s electronics capture all the detector readings simultaneously, typically several hundred times per second. Each such collection corresponds to a single value of 9. Shortly thereafter the electronics capture a subsequent set of readings, this time associated with an angle 9 + A9. The value of A9 is typically 1° or less. The process repeats until every point in the bag has been sampled with rays from 0° to 180° in increments o A9. To accomphsh this requirement, the disk must rotate through an angle of 180° plus the angle at the 

In the 9-s detector-reading matrix, the values tabulated are ln Io/I) as given in Eq. (2), which is the line integral of fj,. It has the property that higher values mean higher thicknesses and densities of material. 

The next level beyond the step-and-shoot method is the helical-scan approach. The conveyor belt of a heftcal-scan system moves continuously at a uniform speed and is synchronized with the rotating disk that holds the X-ray source and detectors. The synchronization ensures that by the time a bag has advanced by 

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Multi-row technology allows sub-millimetric spatial resolution, which is extremely important in the z-axis, thus providing additional information when compared with single-slice CT. The visualization of thin structures such as the stapedial crura and the ossicular ligaments results in being improved by means of multi-row CT also the ability to obtain volumetric data with isotropic voxels permits reliable image reformations in any plane of a section. 

MRI allows data acquisition with a very good soft tissue contrast and multiplanar image acquisition, especially in patients with extensive tumor with invasion of the inferior vena cava. MRI determines cranial extension of the thrombus much more effectively than does single-slice CT. Before the introduction of MDCT scanners, MRI used to be the image modality of choice for... 

Abstract— It is well known that contamination of CT data with scattered radiation rednces reconstrncted CT numbers and introduces cupping artifacts in the reconstructed images. This effect is more pronounced in multi detector CT scanners with extended detector aperture mostly using cone-heam configurations, which are much less immune to scatter than fan-heam and single-slice CT scanners. Accurate... 

In single-slice CT,the most important scan parameters can be provided in the form of a triplet including slice collimation (SC, in mm), table feed/rotation (TF, in mm) and reconstruction increment (Rl, in mm). Depending on clinical indications, a compromise has to be reached between z-axis resolution and required scan length. The effective slice thickness or slice width (SW) can be calculated from slice collimation and pitch, P (=TF/SC). The suggested scan parameters for single-slice spiral CT of the liver are 5/8/4 (SC/TF/Rl) and the SW is 6.2 (Uggowitzer 2003). 

Simulations of the adaptive reconstruction have been performed for a single slice of a porosity in ferritic weld as shown in Fig. 2a [11]. The image matrix has the dimensions 230x120 pixels. The number of beams in each projection is M=131. The total number of projections K was chosen to be 50. For the projections the usual CT setup was used restricted to angels between 0° and 180° with the uniform step size of about 3.7°. The diagonal form of the quadratic criteria F(a,a) and f(a,a) were used for the reconstruction algorithms (5) and (6). 

The data volume, which can be imported as data block or single slices, can be cutted or rebinned (e.g. if the data set is very large) and interpolated (e.g. interpolating intermediate slices between measured CT cuts in the case of 2D-CT). 

With regard to MDCT radiation exposure, several factors must be weighed. There is up to a 4.5% loss of efficiency vs. single-detector row scanners due to absorption of radiation in the z-axis by septa between the detector rows [31]. However, with MDCT, most of the X-ray beam is utilized per rotation due to the increased number of detector rows, with less of a penumbra [31]. Subsequently, these effects balance and the dose efficiency of MDCT has been shown to be comparable to that of single-slice helical CT [31]. 

Companies, including Siemens, General Electric (GE), and IBA, provide SPECT/CT and PET/CT instruments and cyclotrons for hospitals, universities, and pharmaceutical research laboratories. For example, at Yale University, there is a cyclotron, a GE 16 slice scanner, two GE 4 slice scanners, and one GE single slice scanner, all with helical capability. A 64-slice scanner was built in February 2006. The 64 slice scanner replaced a 4 slice scanner in the Emergency Department in October 2006. 

Fig. 3.1. Coronal CT images reconstructed from axial data. The single slice acquisition utilized 5 mm thick sections. The resulting Z-axis resolution is poor. The 4,16 and 64 row scanners utilized 1.25,1, and 0.75 mm thick axial sections respectively. Note improvement in time of acquisition...

In the study of the middle and inner ear we have proposed the following single-slice spiral CT protocol axial and coronal acquisitions beam collimation, 1 mm pitch 1 and 0.5 mm reconstructions spacing (see Chap. 10 on temporal bone for details) (Neri et al. 2000b). In this study all components of the middle ear could be visualized, but also endoluminal views of the bone labyrinth were created (Fig. 7.6). 

Table 13.3. Recommended parameters to obtain a VL using a single-slice spiral CT scanner ...

Klingebiel R, Zimmer C, Rogalla P et al (2001) Assessment of the arteriovenous cerebrovascular system by multi-slice CT. A single-bolus, monophasic protocol. Acta Radiol 42 560-562... 

The introduction of multidetector row computed tomographic (MDCT) scanners in late 1998 opened a new era for CT in general and CTC in particular (Berland and Smith 1998). The use of multiple detector arrays along the z-axis offers substantial benefits related to anatomic coverage, scanning time and longitudinal spatial resolution compared with single-slice spiral CT (SSCT) (Beaulieu et al. 1998 Fenlon et al. 1999 Kara et al. 2001). 

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