Multi-head contrast media injectors offer flexible contrast media management, simplified workflows and increased patient safety.
Contrast delivery is much more controlled and efficient when using a dual-head CT power injector. These medical devices are needed to enable the short imaging times typical of multidetector computed tomography (CT) scanners.
Triple-head injectors allow selection of a second contrast agent when two different contrast agents are used, or switching to full contrast agent containers when two identical contrast agents are used.

See also Contrast Media Injector, Syringeless CT Power Injector, Single-Head Contrast Media Injector, CT Power Injector.

A radiation meter is used to measure radioactivity.
Beta emitting isotopes, such as C-14, P-32, P-33, and S-35, are best detected with a Geiger-Mueller counter (GM).
Gamma emitting isotopes, such as I-125, I-123, I-131, and Tc-99m are easily detected with a gamma meter equipped with a sodium iodide (NaI) probe.
An isotope that cannot be detected with most survey meters, unless present in large activities, is tritium (H-3). Tritium emits beta particles with energies insufficient to enter the sensitive volume of most detectors.

Raw data are the values of all measured detector signals during a scan. After calibration for fluctuations in tube output and beam hardening, the attenuation properties of each x-ray signal are accounted and correlated with the ray position. From these data the CT images are reconstructed including the use of mathematical procedures like convolution filtering and back projection.
Raw data can also be used for later reconstruction of additional planes and images by using a different convolution filter, zoom reconstruction, or an alternative CT number scale.

See also Magnification, Archiving, Number of Measurements and Convolution.

Single-head contrast media injectors ('contrast only') have been first developed in the 1970s. The construction consists of a syringe with the contrast medium inserted into the injector head and a plunger to deliver the contrast medium from the syringe via tubing connected to the patient.
Injectors used in cath lab angiography are often single-head injectors using one syringe.
Angiography contrast delivery systems inject contrast agent into arteries, where air embolisms can present a serious risk. For that reason, cath lab pressure injectors should have air embolism detectors, warning of bubbles in the line before they reach a patient. Air embolisms are not a major issue for CT scans, due to the venous access any small bubbles injected into a vein are expelled through the lungs. Procedures in the interventional suite need low, variable flow rate injections.

See also Contrast Media Injector, Dual-Head CT Power Injector, CT Power Injector, Multi-Head Contrast Media Injector, Syringeless CT Power Injector.

VoLumen® is a low density barium sulfate contrast agent especially designed for MDCT (multi-detector row CT) and PET/CT exams to mark the bowel. Volumen is useful for CT studies of the small bowel and mesenteric vessels.
Positive oral contrast media may limit the delineation between soft bowel tissues and the lumen and may cause artifacts. Water or methyl-cellulose transits very rapidly and may limit bowel distention and soft tissue differentiation. Volumen, similar to water appears hypodense (low Hounsfield values) on CT scan and can be used in conjunction with IV contrast. VoLumen's low density formulation is well-suited for computed tomography enterography.