Below are our articles relating to physics and image quality in CT (Computed Tomography).
Animated CT Generations [1st, 2nd, 3rd, 4th, 5th Gen CT] for Radiologic Technologists
CT scanning prototypes were developed in the late 1960s and this post describes the stages of technological development for CT scanners (Generations 1-5). After demonstrating the differences between these generations…
X-ray Generation, pictorial Guide [Bremsstrahlung, Characteristic]
X-ray tubes used in diagnostic X-ray exams all use the same physical principles including: thermionic emission (boiling off electrons), accelerating electrons by a kiloVoltage potential (kVp), and two physical interactions…
X-ray scatter (collimation, kVp, air gap, thickness, anti-scatter grids) factors every technologist should know.
X-ray scatter due to Compton Scatter generates background haze in x-ray images and there is a desire to reduce the scatter impact on image quality. X-ray scatter depends on several…
X-Ray Interactions, Illustrated Summary (Photoelectric, Compton, Coherent) for Radiologic Technologists and Radiographers
The x-ray interactions are Photoelectric, Compton and Coherent. Photoelectric is mainly responsible for image contrast, Compton contributes to artifacts in the images, and Coherent scattering has little influence in most…
5 reasons why Gonad Shielding will soon be extinct, and motivations for why it was introduced.
The motivation for gonad shielding is to reduce the hereditary specific risks of radiation, and it is still common practice at many institutions. The reasons that shielding will soon be…
Beam Quality, Beam Quantity (mA, kVp, HVL) for Radiologic Technologist
Beam Quality describes the shape of the energy spectrum (i.e. the energy distribution of the x-rays) and beam quantity describes the total intensity of the spectrum (i.e. the area under…
X- ray Resolution (PSF, MTF, NPS, DQE) for radiologic technologists
The spatial resolution of an x-ray or CT system is a measure of how the ability of a system to differentiate small structures. If you imagine imaging a very small…
Illustrated comparison of CT Scan Modes [axial, helical, wide-cone axial, low pitch, high pitch] for Radiologic Technologists
CT (Computed Tomography) scanning can be accomplished with multiple different scan modes which have different characteristics. Axial non-volumetric scanning is how CT began where one (or just a few) slices…
Slip Ring CT pictorial guide [helical, cardiac, perfusion, 4DCT]
After the invention of CT itself and moving from first generation CT to third generation CT the incorporation of slip rings into modern CT is the most import enabler of…
Filtered BackProjection (FBP) Illustrated Guide for Radiologic Technologists
The Filtered BackProjection (FBP) algorithm is the basis for image reconstruction (converting from the measured data to the image) on modern CT scanners. FBP is a fast and direct method…
Contrast Agents (Radiographic contrast agents and iodinated contrast media)
Contrast agents from air to Barium to Iodine play a crucial role in X-ray and CT imaging by improving anatomical contrast and improving the visualization of structures including: GI system,…