Radiology X-Ray physics course

Explore x-ray tube components: cathode, anode, thermionic emission, filament, focusing cap, focal spot, and rotating anode, and learn how vacuum, x-ray window, filters, oil cooling, and lead shielding enable imaging.

Explore how the x-ray tube geometry shapes the effective focal spot and field of view, showing how the cathode filament and anode angle influence image resolution and diagnostic coverage.

Explain the anode heel effect in x-ray beams, where intensity is greater on the cathode side due to focal spot geometry and attenuation. Show how angle and distance influence it.

Understand inherent and added filtration and how they filter low-energy photons to increase penetration and reduce patient dose. Learn about compensatory and trough filters that shape beam uniformity across patients.

Collimate the x-ray beam to shape the field and reduce low energy photons. Lower patient dose while improving image quality by decreasing scatter.

Explore the three main x-ray circuits—the primary, secondary, and filament circuits—and how the primary converts low hospital voltage to high voltage and direct current to drive the tube.

Explore the secondary circuit: transformer and rectifier convert ac to dc for the x-ray tube. Explain single-phase, two-pulse, and three-phase rectifiers and how filament current and kvp govern tube current.

Connects to the cathode from 220-volt hospital supply and uses a step-down transformer with rheostat to regulate filament voltage. Regulate filament current to control tube current and x-ray production.

Explain how bremsstrahlung X-rays form when cathode electrons hit the anode. Show how filters remove low-energy photons to boost image quality and reduce patient dose.

Examine how x-ray beam quality and quantity arise from inner-shell transitions, producing k alpha and k beta lines, and how filament, exposure time, and target material shape the spectrum.

Explore how factors such as filament current, tube potential, filters, target material, and generator type shape the x-ray spectrum, affecting beam quality and quantity.

Exceeding inner-shell binding energy triggers the photoelectric effect and ejects a photoelectron. Increase tissue density raises absorption and iodine's k-edge enhances contrast.

Explore how Compton scatter (quantum scatter) changes photon direction, degrades image quality, and increases patient dose. Note its energy dependence and the equal-probability point with the photoelectric effect.

Explore coherent (rayleigh) scattering in x-ray imaging, comparing elastic scatter with photoelectric and compton interactions, and explain how coherent scatter changes direction without energy loss.

This lecture explains linear energy transfer from photoelectric and Compton interactions, showing how energy transfer to tissue can cause harmful biological effects, with low-energy electrons traveling farther than high-energy ones.

Explore the linear attenuation coefficient and mass attenuation coefficient as they describe x-ray attenuation in tissue, influenced by density, energy, and interactions like photoelectric effect and Compton scattering.

Explore the half value layer and its relationship to the linear attenuation coefficient, including the idea that HVL equals 0.693 divided by μ, as tissue density governs attenuation.

Explore the three main x-ray detector types—screen film radiography, computed radiography, and digital radiography—and how they convert photons to digital signals via scintillation and latent images.

Learn how screen-film radiography uses a cassette with an intensifying screen to convert x-rays into light, reducing patient dose and forming a latent image in silver halide emulsion.

Explain the characteristic curve for screen film radiography, linking exposure to optical density and transmittance, and describe latitude, dynamic range, gamma, and film speed differences.

Explore how computed radiography forms latent images with a cassette-based system, then converts them into digital signals and images via laser scanning, scintillation, and an analog-to-digital converter.

Explore digital radiography by comparing direct and indirect methods with computed and screen-film radiography, and learn how scintillation, detector design, and automatic processing affect spatial resolution.

Understand how indirect digital radiography uses a scintillation layer and a charge-coupled device chip to convert x rays into light and digital signals stored in pixels.

Understand how flat panel detectors in indirect radiography use a scintillation layer to convert x rays to light, then amorphous silicon photodiodes and a thin-film transistor array to create signals.

Explore direct thin film transistor array concepts and contrast direct conversion with indirect scintillation. A potential difference drives electrons, improving image resolution and enabling dose reduction in applications like mammography.

Understand how x-ray scattering degrades image quality. Tissue thickness, field of view, photon energy, and the anti scatter grid influence scatter and image sharpness.

Collimate to reduce the field of view and scatter with cylindrical or cone-shaped collimators; compress tissue thickness, and use an air gap or anti-scatter grid to improve image quality.

Explore how anti scatter grids reduce patient dose and improve image quality by attenuating scattered x rays, with focus on focal and parallel grids, grid cutoff, and bulk factor.

Explore the geometry of blurring and unsharpness and how magnification and geometric blur relate to image sharpness in radiology x-ray imaging.

Apply collimation to reduce the field of view, use compression to thin tissue, and employ anti scatter grids to decrease scatter and improve image quality.