Radiation Physics and Safety Review

Flashcards covering concepts from the Radiation Physics and Safety lecture notes.

What is a characteristic of an X-ray beam?

It is polyenergetic (has many energies).

How many electrons must the K-shell (innermost shell) have?

Two electrons.

What principle must be considered regarding medical radiation exposure?

The benefit must outweigh the risk.

What is a natural radioactive substance found in dirt and air?

Radon.

What is the primary benefit of X-rays in medicine?

Diagnosis.

What is the primary risk associated with X-ray exposure?

Exposure to radiation.

At what speed do X-rays travel?

The speed of light.

What phenomenon refers to an electron losing energy, often through absorption?

Attenuation.

What is the minimum lead equivalency required for lead aprons used in general X-ray exams?

0.25 mm Pb/eq.

What is the minimum lead equivalency required for lead aprons used in fluoroscopy exams?

0.5 mm Pb/eq.

What materials are typically found in an Optically Stimulated Luminescence (OSL) dosimeter?

Aluminum, copper, and tin.

What are the main advantages of an OSL dosimeter?

It is the most sensitive and most accurate.

What is a disadvantage of using an OSL dosimeter?

It provides no immediate readout.

What type of dosimeter uses crystals to absorb electrons?

Thermoluminescent dosimeter (TLD).

Which type of dosimeter resembles a pen and provides an immediate readout?

Pocket dosimeter.

What instruments are used to detect radiation levels in a room?

Field survey instruments.

Which field survey instrument is commonly used in nuclear medicine?

Geiger-Muller.

Under what condition must an occupational worker wear a dosimeter?

When exposed to 10% or more of the effective dose limit.

What are the two main types of secondary radiation?

Scatter, or leakage radiation.

What are the three cardinal principles of radiation protection?

Time, Distance, and Shielding.

How can repeat exposures affect a patient's radiation dose?

They increase the patient's radiation dose.

How does increasing Source-to-Image Receptor Distance (SID) affect patient dose?

It decreases patient dose.

What is considered the best measure of protection for an occupational worker against radiation?

Shielding.

What is a critical practice for patient protection regarding radiosensitive organs?

Placing lead shielding over them.

What radiation dose range is associated with Hematopoietic (bone marrow) syndrome?

2 to 10 Gy.

What is a primary effect of Hematopoietic syndrome?

Decreased blood cells.

How does an increase in radiation dose affect survival time in Hematopoietic syndrome?

It decreases survival time.

What radiation dose range is associated with Gastrointestinal (GI) syndrome?

10 to 50 Gy.

Which organ is most sensitive in the context of GI syndrome?

The small intestine.

What is the typical survival time for individuals affected by GI syndrome?

3-10 days after exposure.

What body systems are primarily affected by Cerebrovascular syndrome?

Central nervous system and cardiovascular system.

What radiation dose causes Cerebrovascular syndrome?

Doses above 50 Gy.

What is the typical survival time for individuals affected by Cerebrovascular syndrome?

A few hours to a couple of days.

What type of radiation interaction occurs when radiation directly targets and damages DNA?

Direct hit.

What is the most common mechanism of biologic damage from radiation?

Indirect hit.

How does an indirect hit cause cell damage?

Radiation ionizes the water in the cell, producing cell damage.

Which advisory group provides recommendations for safe radiation practices to the public?

National Council on Radiation Protection and Measurements (NCRP).

Which enforcement agency is responsible for implementing and enforcing NCRP recommendations?

Nuclear Regulatory Commission (NRC).

What formula is used to calculate Equivalent Dose (EqD)?

Absorbed dose
x WR (Radiation Weighting Factor).

What formula is used to calculate Effective Dose (EfD)?

Absorbed dose x WR (Radiation Weighting Factor) x WT (Tissue Weighting Factor).

What does KERMA stand for in radiation physics?

Kinetic Energy Released in Matter or Air.

What does KERMA measure?

Energy transferred from radiation to a material (J/kg).

What unit measures the rate at which a radionuclide decays?

Curie.

In what fields is the Curie unit commonly used?

Nuclear medicine or radiation therapy.

What type of cells perform all body functions and reproduce through mitosis?

Somatic cells.

What type of cells are reproductive cells that reproduce through meiosis?

Germ cells.

What quantity measures the amount of energy absorbed in a medium?

Absorbed dose.

What is the traditional unit for absorbed dose?

RAD.

What is the SI unit for absorbed dose?

Gray (Gy).

What quantity measures ionization in air?

Exposure.

What is the traditional unit for exposure?

Roentgen (R).

What is the SI unit for exposure?

Coulombs per kilogram (C/kg).

What quantity expresses the biologic response of exposed individuals to the same quantity of differing radiations?

Equivalent dose (EqD).

What is the traditional unit for equivalent dose?

Rem.

What is the SI unit for equivalent dose?

Sievert (Sv).

What type of scattering involves a photon striking an atom, becoming excited, and then releasing excess energy as a photon with the same energy but a different direction?

Coherent scattering (unmodified scattering).

What is the effect of coherent scattering in the diagnostic energy range?

It has a minimal effect.

At what energy levels can coherent scattering typically interact with matter?

Below 10 keV.

What type of scattering involves a photon ejecting an outer-shell electron (recoil electron) and losing some of its energy, with the remainder of the photon energy potentially undergoing further interaction or exiting?

Compton scattering (modified scatter).

What are the primary effects of Compton scattering regarding radiation exposure?

It increases occupational exposure and patient dose.

What type of interaction occurs when an incident photon strikes an inner-shell electron, ejecting it from orbit and creating a photoelectron?

Photoelectric interaction (photoelectric absorption).

What is a significant effect of photoelectric interaction on patient dose?

It increases patient dose.

What interaction occurs when a high-energy photon interacts with the force field of the nucleus, creating a positron and a negatron, followed by an annihilation reaction producing two photons moving in opposite directions?

Pair production.

What is the minimum energy required for a photon to undergo pair production?

1.02 MeV.

Into what two particles does a photon split during pair production?

A positron and a negatron.