FINAL EXAM - MRAD 1307

Flashcards generated from lecture notes on radiation safety and related topics for MRT students.

What effect related to radiation exposure increases in probability as dose increases?

Stochastic effects increase in probability as dose increases.

What describes a threshold dose and its effect?

A threshold dose is established when the effect is evident in 1% of an exposed population; it's the minimum dose at which predictable effects like cataracts, fertility impairment, erythema, or ARS are seen.

What is an expected outcome of 300 mSv exposure to a fertilized oocyte?

Spontaneous abortion

Which dose response curve is best applied to estimating risk of leukemia and breast cancer?

Linear Quadratic Graph

Which dose response graph supports the theory that low doses of radiation present negligible to non-existent risk of cancer?

Threshold dose response graphs

And the theory that all radiation carries some real risk of effect over the course of the lifetime of an exposed population?

Non-threshold dose response graph

What is measured by the following equation: = D x WR x WT?

Effective Dose

SC35 Dose Limits for Radiation workers: Lens of the eye? Whole Body? Pregnant MRTs? Hands/Feet? Skin?

Eye: 100mSv over 5 years, average of 20mSv but a max of 50mSv in any single year. Pregnant workers: 4mSv for the remainder of the pregnancy. Hands/Feet: 500mSv, which is the same as the skin in general.

Shielding requirements for lead aprons during fluoroscopy procedures:

Full wrap-around vest and skirt: 0.5mm Pb eq in the front and 0.25mm Pb eq in the back. Thyroid shields: 0.5 mmPb eq front, .25mm PB eq back. Lead glasses: 0.75 mmPb eq.

Dose threshold for skin erythema?

2Gy

PPE for BBF?

Gloves and gown.

Student exposure in Clinical- Who do you call?

Clinical coordinator.

Patient injury and near miss (good catch) reporting platform?

PSLS: Patient Safety Learning Systems

Annual dose limit for BCIT MRT students?

1 mSv

How do you initially assess your patient for unpredictable/violent tendencies?

Observation and introductory interactions.

Patient makes you feel uncomfortable due to their aggressive and threatening language- what’s your next move?

Call security!

Family members getting upset and being rude?

Empathize but have firm boundaries. Be accountable and do not minimize the situation.

What type of radiation causes ionization?

High-energy or high-frequency electromagnetic radiation

What are some non-EMR forms of radiation?

Particulate radiation (Alpha, Beta particles, Neutrons, Protons)

What are natural sources of radiation?

Terrestrial, cosmic, radon, and some naturally occurring nuclear materials.

What are human-made sources of radiation?

Consumer products, occupational exposure, medical imaging, air travel, and nuclear power.

What is the highest contributor to natural background radiation?

Radon (42%)

How much radiation comes from medical sources on average?

2.3 mSv

What is the average total radiation dose per person per year?

5.5 mSv

What are the three exposure classifications?

Occupational, Medical, Public/Background

What happens when LET increases?

Increased ionization and greater chance of direct biological effects.

What is the formula for LET?

LET = keV/µm

What is a direct effect of radiation?

Radiation directly hits DNA, RNA, proteins, or enzymes causing damage.

What causes indirect radiation effects?

Radiolysis of water creates free radicals that damage cells.

What is the primary interaction of low LET radiation in the body?

Indirect action through water radiolysis.

What free radicals are involved in low LET damage?

Hydroxyl (OH) and Hydroperoxyl (HO2)

Are X-rays high or low LET?

Low LET

What is the main mechanism of X-ray biological damage?

Indirect effects

What does the Law of Bergonie and Tribondeau state?

Radiosensitivity increases with reproductive activity and decreases with differentiation.

What factors increase radiosensitivity?

High cell division, low specialization, high metabolism, high oxygenation, mitosis duration.

Which system is the most radiosensitive?

Hematopoietic system

Name two moderately radiosensitive tissues.

Epidermal tissues, reproductive cells.

What tissues are the least radiosensitive?

Mature bone, cartilage, muscles, nervous system.

What tissues have a weighting factor of 0.12?

Bone marrow (red), breast, colon, lungs, stomach, and 'remainder'.

Do testes and ovaries have equal weighting factors?

yes—testes: 0.08 (male), ovaries: 0.08 (female).

What are early effects of radiation exposure?

Acute Radiation Sickness from large whole-body doses.

What are late effects of radiation exposure?

Carcinogenesis, cataracts, birth defects.

What unit measures absorbed dose?

Gray (Gy)

What is the unit for effective dose?

Sievert (Sv)

How is equivalent dose calculated?

Equivalent dose = Gray × Quality Factor

What is DAP?

Dose Area Product = mGy × area (cm²), e.g., 20 × 20 × 20 mGy = 8000 mGy·cm²

What is the purpose of Safety Code 35?

Ensure safe use of X-ray equipment in medical facilities.

What is a key responsibility of MRTs under SC35?

Minimize unnecessary exposure and monitor personal exposure with dosimeters.

What is the annual whole-body dose limit for radiation workers?

20 mSv/year averaged over 5 years (max 50 mSv/year).

What is the annual limit for the public?

1 mSv/year averaged over 5 years.

What are the four main dose reduction strategies?

Justification, Optimization, Repeat Reduction, Distance/Shielding.

How can MRTs optimize exposure?

Adjust technical factors (e.g., increase kVp, reduce mAs), use proper positioning, and collimation.