Ionizing radiation

What do ionizing radiations do to matter and living organisms?

Ionizing radiations penetrate deep into matter, ionize atoms, and break chemical bonds, affecting living organisms.

What happens during ionization?

An electron is removed from the atomic shell, creating a pair of oppositely charged particles.

What types of particles are included in direct ionizing radiation?

Charged particles such as alpha particles (α), beta particles (β), electrons (e-), positrons (e+), and protons (p).

How do direct ionizing radiations interact with atoms?

They ionize atoms by direct collision.

What are examples of indirect ionizing radiations?

High-energy photons like gamma rays and X-rays, and electrically neutral particles like neutrons.

How do indirect ionizing radiations interact with matter?

They interact with atoms through their electromagnetic fields, ejecting electrons from atomic shells.

What is secondary ionization and how is it produced?

Secondary ionization occurs when electrons from direct and indirect radiation collide with other electrons, causing further ionization.

What factors determine how effective the ionizing process is?

The mass, energy, and charge of the ionizing particle, as well as the atomic characteristics of the matter.

What is linear ionization (NI)?

The number of ion pairs produced by ionizing particles per unit of distance through matter.

What does linear energy transmission (LET) represent?

The energy transmitted locally (given to the material) by particles per unit of distance.

What is the range (R) in ionizing radiation?

The depth in a substance where the intensity of radiation decreases to half.

What processes describe how photon radiation interacts with matter?

photoelectric absorption, Compton scattering, and couple production.

What happens during the photoelectric effect?

A photon interacts with an electron, ejecting it and splitting the photon's energy into ionization energy and the electron's kinetic energy.

On what factors does the probability of the photoelectric effect depend?

The photon's energy (hv) and the type of matter (atomic number Z, density ρ).

What happens during Compton scattering?

A photon interacts with a free or weakly bound electron, transferring part of its energy and altering its direction and energy.

What is couple production, and what energy threshold is required for it to occur?

Pair production creates an electron-positron pair from a photon (that releases energy when the two collide with each other) with energy ≥1.022 MeV.

What happens to the positron produced in pair production?

It quickly interacts with an electron, leading to annihilation and the creation of photons.

How is total attenuation of photon radiation quantified?

By the decrease in radiant flux based on material properties like density and atomic number.

What is the half-value layer (HVL)?

The thickness of material required to reduce photon flux by 50%.

What are the typical wavelengths of medical X-rays?

3pm (picometers) to 10 nm (nanometers)

What are the natural and artificial sources of X-rays?

Natural sources include cosmic rays, while artificial X-rays are produced using X-ray tubes.

How are X-rays generated in an X-ray tube?

Electrons emitted from a heated thermocathode are accelerated toward an anode, where their collision produces X-rays.

What is meant by characteristic X-ray radiation?

when an inner-shell electron is ejected, and an outer-shell electron fills the vacancy.

What is braking radiation (Bremsstrahlung)?

Incoming electron from the cathode going towards the nucleus decelerates losing energy that is released as an X-ray that can have different waves lengths producing a continuous spectrum.

How does voltage applied in an X-ray tube affect the radiation produced?

Higher voltage produces shorter wavelengths and higher-energy photons.

What happens to the intensity of the X-ray beam when the current in the X-ray tube increases?

The intensity increases, but the energy characteristics of the photons remain unchanged.

Why is filtering low-energy X-rays important in medical applications?

It improves safety and image quality by reducing unnecessary radiation absorption in soft tissues.

What is the linear attenuation coefficient? based on what?

how easily a material can be penetrated by radiation based on atomic number and photon energy.

How does adjusting the voltage and current in an X-ray tube help in medical diagnostics?

Voltage affects photon energy, while current controls beam intensity, enabling appropriate X-ray beams for diagnostics or therapy.

What is dosimetry?

Dosimetry is the science of measuring and calculating radiation dose, crucial for understanding radiation effects on humans, ensuring safety, and minimizing harm.

What does exposure measure?

Exposure measures the ionization potential of x-rays or gamma rays in the air but does not indicate the absorbed radiation. Unit: Roentgen (R).

What is absorbed dose?

The amount of radiation energy transferred to a material. Unit: Gray (Gy), where 1 Gy = 1 Joule/kg.

What is equivalent dose?

Equivalent dose accounts for the varying biological impact of different radiation types. Unit: Sievert (Sv). Alpha particles are more damaging than x-rays, for instance.

What is effective dose?

Effective dose considers tissue-specific sensitivity to radiation, quantified by the tissue weighting factor (TWF). Unit: Sievert (Sv).

What is dosage?

Dosage is a controlled radiation dose administered over a specific period.

Which tissues have higher radiation sensitivity?

Different tissues exhibit varying sensitivities to radiation. For instance, bone marrow has a higher TWF compared to muscle or skin due to its higher vulnerability.

What factors predict radiation behavior and damage?

LET (Linear Energy Transfer), radiation type (e.g., alpha vs. x-rays), and tissue properties help predict radiation behavior and potential damage.

Which cells are more susceptible to radiation damage?

Cells undergoing division (e.g., in bone marrow) are more susceptible to radiation damage than stable cells.

What is a Linear Accelerator (LINAC)?

A device used in radiotherapy to produce high-energy x-rays or electron beams for targeting cancerous tumors.

What are the features of LINAC?

LINAC generates and shapes radiation beams precisely to conform to the tumor's shape while minimizing radiation exposure to surrounding healthy tissues.

How does LINAC minimize damage to healthy tissues?

LINAC delivers a maximum dose to the tumor and a reduced dose to normal cells.

What is external beam radiation?

Radiation delivered from outside the body, ensuring precision and control for effective tumor treatment while reducing collateral damage.

What is dosimetry?

Dosimetry is the science of measuring and calculating radiation dose, crucial for understanding radiation effects on humans, ensuring safety, and minimizing harm.

What does exposure measure?

Exposure measures the ionization potential of x-rays or gamma rays in the air but does not indicate the absorbed radiation. Unit: Roentgen (R).

What is absorbed dose?

The amount of radiation energy transferred to a material. Unit: Gray (Gy), where 1 Gy = 1 Joule/kg.

What is equivalent dose?

Equivalent dose accounts for the varying biological impact of different radiation types. Unit: Sievert (Sv). Alpha particles are more damaging than x-rays, for instance.

What is effective dose?

Effective dose considers tissue-specific sensitivity to radiation, quantified by the tissue weighting factor (TWF). Unit: Sievert (Sv).

What is dosage?

Dosage is a controlled radiation dose administered over a specific period.

Which tissues have higher radiation sensitivity?

Different tissues exhibit varying sensitivities to radiation. For instance, bone marrow has a higher TWF compared to muscle or skin due to its higher vulnerability.

What factors predict radiation behavior and damage?

LET (Linear Energy Transfer), radiation type (e.g., alpha vs. x-rays), and tissue properties help predict radiation behavior and potential damage.

Which cells are more susceptible to radiation damage?

Cells undergoing division (e.g., in bone marrow) are more susceptible to radiation damage than stable cells.

What is a Linear Accelerator (LINAC)?

A device used in radiotherapy to produce high-energy x-rays or electron beams for targeting cancerous tumors.

What are the features of LINAC?

LINAC generates and shapes radiation beams precisely to conform to the tumor's shape while minimizing radiation exposure to surrounding healthy tissues.

How does LINAC minimize damage to healthy tissues?

LINAC delivers a maximum dose to the tumor and a reduced dose to normal cells.

What is external beam radiation?

Radiation delivered from outside the body, ensuring precision and control for effective tumor treatment while reducing collateral damage.

What is a LINAC and what does it do? / A LINAC (Linear Accelerator) generates high-energy X-rays or electron beams used in cancer treatment to target tumors.

How does LINAC minimize damage to healthy cells?

LINAC shapes and directs radiation beams precisely to the tumor, reducing exposure to surrounding healthy tissues.

What is the primary use of LINAC in radiotherapy?

LINAC is used in external beam radiotherapy to deliver the maximum radiation dose to the tumor while sparing normal cells.

What is radioactivity, and what does it involve?

Radioactivity is the process by which unstable nuclei release energy through radioactive decays, including alpha, beta, and gamma emissions.

What happens during alpha decay?

Alpha decay releases a helium nucleus consisting of 2 protons and 2 neutrons, reducing the parent nucleus's atomic number by 2 and mass number by 4.

How does beta decay occur, and what are the types?

Beta-minus decay: A neutron changes into a proton, releasing an electron and an antineutrino.

Beta-plus decay: A proton becomes a neutron, releasing a positron (antielectron) and a neutrino.

What is gamma decay, and how is it different from alpha and beta decays?

Gamma decay involves the release of high-energy photons, emitting energy without releasing particles. It is highly penetrating and occurs when a nucleus sheds excess energy.

What are half-life and decay constant, and how are they related?

Half-life: The time it takes for half the atoms in a radioactive sample to decay.

Decay constant: The fixed probability of a single atom decaying, determining the rate of decay. A larger decay constant means faster decay.