PP: History, Atoms, Prime Factors

Atomic Structure in Radiography

The fundamental level at which x-ray photons interact with the human body and image receptors, influencing radiation dose and image appearance.

Atom

The smallest unit of an element.

Element

A group of identical atoms sharing specific chemical behaviors, unable to be broken down by ordinary means.

Nucleus

The central part of an atom, made up of protons and neutrons.

Proton

A basic atomic particle with a positive charge (+), located in the nucleus.

Neutron

A basic atomic particle with no charge, located in the nucleus.

Electron

A basic atomic particle with a negative charge (-), orbiting the nucleus in defined energy levels or orbital shells.

Atomic Number (Z)

The number of protons in an atom.

Mass Number (A)

The sum of the number of protons and neutrons in an atom.

Ionization

The process of adding or removing electrons from atoms, which can be caused by x-rays.

Electrical Charge

A characteristic of matter.

Neutral Atom

An atom with an equal number of protons and electrons, resulting in no net electrical charge.

Negative Ion

An atom where the negative charges (electrons) outnumber the positive charges (protons).

Positive Ion

An atom where the positive charges (protons) outnumber the negative charges (electrons).

Ionizing Radiation

Radiation capable of causing ionization, requiring an order from a licensed practitioner for patient exposure in radiography.

Aluminum (Al)

An element used in radiography as x-ray filters. Z-13

Barium (Ba)

An element used in radiography as a contrast/dye agent. Z-56

Iodine (I)

An element used in radiography as a contrast/dye agent. Z-53

Lead (Pb)

An element used in radiography for shielding, such as in aprons and walls. Z-82

Hydrogen (H)

Basic Z-1

Helium (He)

Basic Z-2

Carbon (C)

In the body. Z-6

Oxygen (O)

In the body. Z-8

Calcium (Ca)

In the body. Z-20

Tungsten (W)

An element used in radiography for the x-ray tube. Z-74

Rhenium (Re)

An element used in radiography for the xray tube. Z-75

Uranium (U)

An element that is radioactive. Z-92

Anode

The positive electrode in the X-ray tube, typically a tungsten/rhenium anode disk, which is the target for electron bombardment.

Cathode

The negative electrode in the X-ray tube, containing a filament in a focusing cup, where electrons are produced.

Glass envelope

The vacuum-sealed enclosure that houses the components of the X-ray tube.

Prime Factors

The three main factors that affect X-ray emission: milliamperage-seconds (mAs), kilovoltage peak (kVp), and distance (D).

mAs

Milliamperage (mA) multiplied by exposure time (seconds); controls the number (quantity) of electrons passing from the cathode to the anode and is directly proportional to radiation quantity and radiographic density.

kVp

Kilovoltage peak; controls the penetrability, energy, quality, and hardness of the X-ray beam, also impacting quantity.

Distance (D)

Also known as Source Image Distance (SID); the distance from the X-ray tube to the image receptor.

Quantity of X-rays

The number of X-ray photons produced, primarily controlled by mAs.

Quality of X-rays

The penetrability and energy of the X-ray beam, primarily controlled by kVp.

Heterogeneous beam

An X-ray beam consisting of photons with different energies.

mA (Milliamperage)

Directly proportional to radiation quantity and radiographic density/brightness; inversely related to exposure time to maintain density.

Exposure Time (seconds)

Directly proportional to radiation quantity and radiographic density; inversely related to mA to maintain density.

Radiographic density

The degree of blackness or darkness on a radiograph, directly related to mAs and exposure time.

Penetration (X-rays)

The ability of X-rays to pass through anatomic tissues; increased by higher kVp and decreased by lower kVp.

Absorption (X-rays)

The process by which X-ray photons are stopped by anatomic tissues; decreased by higher kVp and increased by lower kVp.

SID (Source Image Distance)

The distance from the X-ray tube to the image receptor; affects the required mAs and the size of the image.

Image Receptor (IR)

The device that captures the X-ray image.

Radiographic Quality Factors

Properties that determine the diagnostic utility of an X-ray image, categorized as photographic (visibility) and geometric (sharpness) properties.

Photographic properties

Factors affecting the visibility of an X-ray image, including receptor exposure and contrast.

Geometric properties

Factors affecting the sharpness of an X-ray image, including spatial resolution and distortion.

Receptor Exposure

A photographic property related to the overall visibility of the image on the image receptor.

Contrast

A photographic property that describes the difference in brightness or density between adjacent areas on a radiograph, affecting the visibility of structures.

Spatial Resolution

A geometric property affecting sharpness; the ability to visualize small objects and fine detail.

Distortion

A geometric property affecting sharpness; the misrepresentation of the true size or shape of an object on a radiograph.

Wilhelm Conrad Roentgen

The founding father of x-ray, who conducted experiments in a German laboratory investigating the properties of cathode rays.

Discovery of X-Ray

Occurred on November 8, 1895, when Wilhelm Conrad Roentgen noticed a piece of paper coated with barium platinocyanide glowing during experiments with a cathode ray tube.

First produced radiograph

A 'photograph' of Roentgen's wife's hand using the new x-light, created on December 22, 1895.

Henri Becquerel

Discovered natural radioactivity in 1896.

Natural radioactivity

Discovered by Henri Becquerel in 1896, involving three types of radiation: Alpha particles, Beta particles, and Gamma rays.

Fluoroscope

Invented by Thomas Edison in 1896, it allows for real-time video imaging, a process referred to as fluoroscopy.

CR (Computed Radiography)

An early digital imaging technology introduced in the early 1980s.

DR (Digital Radiography)

A more advanced digital imaging technology introduced in 1996.

Digital Imaging

Made possible by advances in computer power and miniaturization technology, aiming to maximize diagnostic information while minimizing radiation exposure.

ALARA

An acronym for 'As Low As Reasonably Achievable,' a principle to minimize radiation exposure to the public.

PACS (Picture Archiving and Communication System)

Introduced in 1982, it allows for the storage of images and remote access to CR/DR images by ordering providers and radiologists.

High-quality x-ray image

An image of sufficient quality that a radiologist can interpret it accurately to assist in correctly diagnosing the patient.