RADIOLOGY LECTURE 2 ~~

X-rays are produced when high-energy electrons hit a target, losing energy and emitting photons.

A range of X-ray photon energies produced when electrons are decelerated in various ways.

Maximum energy of a photon in the continuous X-ray spectrum.

Specific energy levels of X-rays emitted by the target material.

High voltage used to accelerate electrons, determining photon energy.

Ability of X-rays to pass through materials.

Higher kV results in more photons and higher-energy photons.

Packets of energy that make up X-rays.

The number of protons in an atom's nucleus.

Limits X-ray beam size, preventing scatter.

Sets target-to-patient distance for safe X-ray procedures.

Removes low-energy X-rays, reducing patient exposure.

Specific X-ray energies produced by target atoms.

Lower kV increases contrast by reducing shades of gray; higher kV decreases contrast by enabling more photon penetration and reducing patient dose.

Specific X-ray energies produced when an electron moves to a different energy level, characteristic of the target material.

Requires 70kV or more to produce characteristic spectrum; lower voltage doesn't have enough energy to knock out inner electrons.

Tube head, glass X-ray tube, filament, tungsten target, copper block, oil, step-up transformer, spacer cone.

Cools the X-ray tube by removing heat generated during X-ray production.

Increases incoming voltage (240V) to the high voltage (60-70kV) needed for the X-ray tube.

Voltage (kV), milliamperes (mA), and exposure time.

Determine photon quantity; higher mA provides more photons, leading to a darker image.

99% of the energy input is released as heat; only 1% is X-rays.

Reduces radiation dose by 50%; recommended dimensions are 40mm x 50mm.

Removes low-energy photons which cannot penetrate; reduces patient dose.

Low energy is absorbed in soft tissue, is less penetrating and more dangerous; high energy is more penetrating and useful for diagnosis.

Determined by the energy of the accelerating electrons, which is controlled by the applied voltage (kV).

Distance from the focal spot on the target to the patient; longer FSD reduces patient dose.

200mm, although 300mm is better