Image quality is an important value of all radiographic imaging procedures. Accurate measures of both image quality and patient radiation risk are needed for effective optimization of diagnostic imaging. Images are acquired for specific purposes, and the result depends on how well this task is performed. The imaging performance is mainly influenced by the imaging procedure, examined object, contrast agents, imaging system, electronic data processing, display, maintenance and the operator. Spatial resolution (sharpness), contrast resolution and sensitivity, artifacts and noise are indicators of image quality.
A high image contrast provides the discrimination between tissues of different densities.
The image resolution states the distinct visibility of linear structures, masses and calcifications.
Noise and artifacts degrade the image quality. In computed tomography (CT), high spatial resolution improves the visibility of small details, but results in increased noise. Increased noise reduces the low contrast detectability. Noise can be reduced by the use of large voxels, increased radiation dose, or an additional smoothing filter, but this type of filter increases blurring.
An image acquisition technique taking these facts into account maximizes the received information content and minimizes the radiation risk or keeps it at a low level.

See also As Low As Reasonably Achievable.

Noise is an undesirable background interference or disturbance that affects image quality. The image noise is commonly characterized by the standard deviation of CT numbers in the image of a uniform object (phantom - generally water) relative to the difference in CT numbers between water and air.
Noise is an important limiting factor of CT image quality and is characterized by a grainy appearance, sometimes described as a salt and pepper pattern. Noise as a result of low radiation dose requires a higher tube current (mA) in combination with narrow slices to maintain image noise at an acceptable level.

Arrhythmia rejection is a method to reject irregular RR intervals (time duration between two consecutive R waves of the electrocardiogram) in cardiac gating during cardiovascular imaging and to improve the image quality, whereby the cardiac frequency is used as the basis of the normal heart rate. The RR interval window determines the percentage variation of the heart rate. Variations of the acquired data outside the window are rejected and not used in the image reconstruction. Also one interval after the arrhythmic beat will be rejected. Arrhythmia rejection may be inappropriate for patients with certain pathologies, because if the RR interval is constant long, short, long, - all intervals would be rejected.

Breast imaging methods include mammography (mammogram), ultrasound, breast MRI, positron emission tomography, xeromammography, diaphanography and thermography.
Mammography is widely used as a screening method and diagnostic tool for breast cancer detection or evaluation of breast disease. Digital mammography takes multiple thin digital image 'slices' through the breast, which provides higher potential to see a small mass within dense tissue. The mammography quality standards act guarantees a high image quality.
Breast ultrasound (also called ultrasonography) should only be used as an additional imaging modality to evaluate specific breast abnormalities, especially to differentiate cystic from solid masses. Ultrasound is also used to guide needle breast biopsies.
Magnetic resonance imaging (MRI) is useful for breast MRI screening in cases of high cancer risk. In addition, multifocal breast cancer can be missed by standard practice mammography and can be early detected with breast MRI.

Contrast media injectors are part of the medical equipment used to deliver fluids in examinations such as CT, MRI, fluoroscopy and angiography. Many of these diagnostic imaging procedures include the administration of intravenous contrast agents to enhance the blood and perfusion in tissues.

Mainly there are two types of injector technology:
See also Single-Head Contrast Media Injector, Dual-Head CT Power Injector, Syringeless CT Power Injector.

The use of x-ray contrast agents in computed tomography (CT) began with a hand injection by the radiologist in the scan room. During its history, CT scanners have made great improvements in speed and image quality. Actual CT systems with multiple detectors allow scan times of a few seconds per body region. Some CT protocols require multiphase scans, where a body region is imaged with a single bolus of contrast in different blood flow phases. Automatic power (pressure) contrast media injectors are required to provide precise control of flow rate, volume and timing of injection. The use of a saline bolus following contrast administration reduces the volume of contrast required.

Most relevant topics for the use of a power injector in medical imaging procedures such as contrast enhanced computed tomography (CECT):
Must have basic injector control options:
Examples of other injector control options: