Intro Med Image Quiz 11/2

Ionizing Radiation

Radiation that produces ions

What does ionizing radiation do?

Cause damage to living cells

Is ionizing radiation damage repairable?

Some damage is, some damage isn't

What are the two types of ionizing radiation that everyone is exposed to?

Natural/background and human-made

What are some examples of background radiation?

Cosmic (sun/stars), elements (uranium/radium), substances in foods, water, and the air

How does higher altitude make a difference in exposure to background radiation?

The higher the altitude, the more cosmic radiation you receive

Over half of the amount of radiation the general public receives is from ___________

Cosmic radiation

What are some examples of human-made radiation?

Fallout from nuclear weapons testing and nuclear power plants, industrial radioactive materials, medical and dental exposures

What accounts for 90% of the general public's exposure in human-made radiation?

Diagnostic medical and dental exposures

NCRP stands for

National Council on Radiation Protection and Measurements

When was the NCRP established, and who was it established by?

1964 by the U.S. Congress

What is the primary function of the NCRP?

To provide information and recommendations about radiation measurements and protection

How do they facilitate research?

Using a pooling of resources

Who do they have cooperative efforts with?

International governmental and private organizations

What are two examples of radiation protection agencies?

Atomic Energy Commission (AEC) and Environmental Protection Agency (EPA)

What is an erythema dose?

Amount of radiation required to turn the skin red

Why are measurements in place?

As a method to measure radiation doses

What is an absorbed dose?

Energy absorbed per unit mass of tissue

What does an equivalent dose do?

Takes the type of radiation into account

What is an air kerma a measurement of?

Radiation dose in air

What is "gray" a measurement of?

Absorbed dose

What is "sievert" a measurement of?

Effective dose

What is "becquerel" a measurement of?

Radioactivity (nuclear medicine)

What is the reasoning behind effective dose limits?

Overall harm might be produced by a given absorbed dose of radiation into human tissues

What do the effective dose limits adhere to?

Radiation protection guidelines

Why are dose limits important?

No radiation dose is 100% safe

What does ALARA stand for?

As low as reasonably achievable

What is the limit in millisieverts (mSv) for an occupational worker's whole body?

50

What is the limit in millisieverts (mSv) for an occupational worker cumulatively?

10mSv * age (years)

What is the limit in millisieverts (mSv) for an occupational worker's lens of the eye?

150

What is the limit in millisieverts (mSv) for an occupational worker's localized areas of the skin, hands, and feet?

500

What is the limit in millisieverts (mSv) for the general public's frequent exposure?

1

What is the limit in millisieverts (mSv) for the general public's infrequent exposure?

5

What is the limit in millisieverts (mSv) for an embryo/fetus per month, during gestation

0.5

What is the limit in millisieverts (mSv) for and embryo/fetus total, during gestation?

5

What are some of the different interactions of x-rays with matter?

Ionization, absorption, scatter, photoelectric effect, and compton scatter

What is the most common form of interaction between x-rays and matter?

Photoelectric effect

What is the photoelectric effect?

X-ray photon ejects inner shell electron, and the photon is absorbed by the matter, creating an ion pair

What is compton scatter?

X-ray photon interacts with the outer shell of the electron, creating an ejected compton electron and scattered x-ray photon

What happens to scattered x-ray photons?

They lose energy and can change direction

What are the 4 different biological effects of ionizing radiation?

No cellular damage, repairable cellular damage, irreparable cellular damage, and cell death

What is the direct hit theory?

Radiation interacts with the DNA, which can impact mitosis and meiosis

What is the indirect hit theory?

Radiation interacts with water in the cell, impacting the radiolysis of water and free radicals

Who created the law of radiosensitivity?

Bergonie and Tribondeau

Radiosensitive cells are cells that are _______

rapidly dividing, immature, and/or nonspecialized

Which type of cell is the most radiosensitive?

Lymphocytes

Which type of cell is the most radioresistant?

Nerve cells

Why are nerve cells the most radioresistant?

They don't divide

What is the latent period?

Time between initial irradiation and the occurrence of biological changes

What is a short term effect of radiation exposure?

Acute radiation syndrome (ARS)

How does ARS happen?

High, whole-body doses

When does ARS appear?

Minutes, hours, or days after exposure

Can ARS happen from diagnostic radiation doses?

No

What are the two types of long term effects of radiation exposure?

Somatic and genetic

What is the somatic effect?

Occurs in general body cells (cancer, cataracts)

What is the genetic effect?

Occurs in germ cells (sexual reproduction)

Define carcinogenic

Cancer causing agent

What are some examples of previous populations that had long term exposure to radiation?

Radium dial painters, uranium mine workers

How do genetic effects occur?

Gonads must have been exposed to ionizing radiation

What is the external source of exposure?

X-rays

What is the internal source of exposure?

Radionuclides

What are examples of radionuclides?

Radiation therapy, nuclear medicine, radioactive half life

What are the three cardinal principles to reduce radiation exposure?

Minimize time, maximize distance, maximize shielding

What are the ways to set the exposure factors to reduce radiation exposure?

Optimal kVp, lowest possible mAs, short exposure time

Why is a short exposure time important

Decreases chance of voluntary motion by patient

Why is it important to not have motion blur in an X-Ray?

Image would have to be repeated, thus exposing the patient to more radiation

What is the inverse square law?

As distance from the radiation source increased, the exposure to radiation decreases

What is aluminum used for?

Absorb low-energy beans that contribute to patient skin dose

What is the required minimum total filtration for equipment operating above 70 kVp?

2.5 mm Al

What are grids good for?

Absorbing scatter radiation

What is collimation?

Restriction of the primary beam to a limited area

How can collimation be set?

Manually or automatically with Positive Beam Limitation (PBL)

How do repeat exposures effect the patient?

Doubles the radiation dose to the patient

When is a gonadal shield used?

Whenever the gonads are near the primary beam but are not the anatomy being evaluated

By how much does a gonadal shield reduce gonadal radiation dose?

95%

What is a gonadal shield composed of?

Lead

What is the most common type of gonadal shield?

Flat, contact shields

What are some of the personal protective equipment that RTs wear?

Gloves, aprons, and glasses

How far from the exposure should the RT stand?

6 feet minimum

What is the most effective means of protection?

Distance

What are two structures used to protect the RT?

Shielded booth and portable shield

Should an RT hold patients?

No, instead, use restraining devices

What is a dosimeter?

Provides a record of exposure

What are the two types of dosimeter?

Optically stimulated luminescent dosimeter (OSL) and thermoluminescent dosimeter (TLD)

Where is a dosimeter worn?

At the collar outside the apron

Define ethics

The study of moral principles and values

Define attitudes

Feelings and emotions

Define creed

A fundamental set of beliefs

Define modesty

Propriety of dress, speech, or conduct

Define dignity

State of honor or esteem

Define morals

Right actions based on religious teachings; honesty, fairness, compassion

Define personal obligation

To be the best you can be

Define standards of conduct

define professional behavior

Define non-maleficence

To do no harm

What is confidentiality?

Information about patients cannot be revealed; HIPAA

What is the cardinal concept for all healthcare professionals?

Confidentiality

What are the core ethical values?

Compassion, honesty, integrity, accountability, fairness, loyalty, and respect

What is a code of ethics?

Hallmark of professional behaviors; professionals have a moral and legal duty to adhere to rules and standards

What percent of communication is verbal?

35%

What percent of communication is nonverbal?

65%