Radiography and Atom Structure

History of Radiography

Alpha (\alpha) particles: These are heavy particles with weak penetrating power. They can be stopped by materials such as paper or human skin.
Beta (\beta) particles: These are lighter particles than alpha particles and possess more penetrating power. They can be stopped by materials like aluminum.
Gamma (\gamma) rays / X-rays: These are forms of electromagnetic radiation and are highly penetrating. They require dense materials like lead or concrete to stop them.

Invented by Thomas Edison in 1896.
This technology allows for real-time imaging of internal structures using a continuous X-ray beam.

CR (Computed Radiography): This method uses imaging plates to capture the X-ray image.
DR (Digital Radiography): This method utilizes flat-panel detectors and is generally considered faster than CR, eliminating the need for traditional cassettes.

As Low As Reasonably Achievable: This is a fundamental safety principle in radiography aimed at minimizing radiation exposure to patients and personnel.

Picture Archiving and Communication System: This system is used for storing, retrieving, and sharing digital medical images, allowing for efficient management of radiographic data.

Protons: Carry a positive (+) electrical charge and are located inside the nucleus of an atom.
Neutrons: Carry no electrical charge (neutral) and are also located inside the nucleus.
Electrons: Carry a negative (-) electrical charge and orbit around the nucleus.

Atomic Number (Z): Represents the number of protons in an atom's nucleus.
Mass Number (A): Represents the total number of protons plus neutrons in an atom's nucleus.

Negative Ion (anion): An atom that has gained extra electrons, resulting in a net negative charge.
Positive Ion (cation): An atom that has lost electrons, resulting in a net positive charge.

Atom: The smallest unit of matter that retains the chemical properties of an element.
Element: A pure substance composed of only one type of atom.
Matter: Anything that has mass and occupies space.

Ionization: The process of adding or removing electrons from an atom, thereby converting it into an ion.

Directly Proportional: When one quantity increases, the other quantity also increases.
- Example: As mAs (milliamperage-seconds) increases (mAs \uparrow), image density (blackness) increases (density \uparrow).
Inversely Proportional: When one quantity increases, the other quantity decreases.
- Example: As kVp (kilovoltage peak) increases (kVp \uparrow), image contrast (difference between black and white) decreases (contrast \downarrow).

Radiolucent: Refers to materials with a low atomic number through which X-rays pass easily. These areas appear black on a radiograph. Examples include air and soft tissue.
Radiopaque: Refers to materials with a high atomic number that absorb X-rays significantly. These areas appear white on a radiograph. Examples include bone and metal.
Quantum Mottle: A grainy or speckled appearance on a radiographic image, caused by too few X-ray photons reaching the image receptor (often due to low mAs settings).

Quality (Penetrating Power): Primarily controlled by kVp.
Quantity (Number of X-rays): Primarily controlled by mAs. The formula for mAs is: mAs = mA \times time.

Higher kVp not only results in a higher quality (more penetrating) X-ray beam but also leads to a slightly increased quantity (number) of X-ray photons.
mAs directly alters the quantity of X-rays produced, but it does not directly influence the quality or penetrating power of the beam.

Utilize a short exposure time.
Provide clear patient instructions, such as breath-holding commands.
Employ immobilization techniques or devices if necessary to prevent patient movement.