Rad Protection Unit 1 exam

radiation definition

the transfer of energy from one location to another

the energetic form of radiation is called

x-ray

altered atoms or molecules making up positive and negative charged particles found in x-rays are called

ions

x-rays are classified as ______ due to the electrical charge effect

ionizing radiation

fundamental properties of x-rays

• can have varying degrees of penetration in normal tissue depending on energy

• travel in straight lines at the speed of light until they interact with atoms

• have wide range of energies within the x-ray bean; heterogenous, not monoenergetic

living tissue can be damaged by exposure to ionizing radiation called

biological effects

effective measures to safeguard from unnecessary exposures from ionizing radiation

• patients

• personnel

• general public

technologists and radiologists are trained how to safely limit radiant energy

1. safe operation of x-ray equipment

2. follow protocols and procedures

3. set correct techniques for patients and limit exposure

4. use shielding when appropriate

Proper technique examples to minimize exposure

technique books and proper measuring of body part

procedural factors examples to minimize exposure

immobilizations, proper image receptor, positioning around the patients limitations

human determinants examples to minimize exposures

pathological conditions, body habitus, movement

unnecessary exposure doesn’t benefit a person in terms of

1. diagnostic information

2. enhancing the quality of the study

diagnostic efficacy

• the degree to which the diagnostic study reveals the presence or absence of a disease in a patient, while adhering to radiation safety guidelines

• provides the basis for the justification of procedures

good voluntary risk is imaging for:

• screening purposes

• injuries

• illnesses

Technologist responsibilities- quality patient care, quality images

• standards of practice

• ASRT code of ethics (5 and 7)

• technique- use smallest amount of exposure to produce a good, diagnostic image

• ALARA

• minimal repeats- optimal image the 1st time, repeats cause increased exposures to patient and technologist

• proper shielding - reduces exposures

• follow protocols- be aware of rules of your department

• be educated in safe operations

radiologist/ physician responsibilities

• consulting

• do not order unnecessary exams

• trained radiologist- utilize some safe practices as the technologist when performing studies

employer responsibilities

• implement and maintain radiation safety program

• supply resources- when necessary

• written policy- describing ALARA and the commitment of managing it

• exposure audit

ALARA

• keep radiation “as low as reasonably achievable” for patients and personnel (1954 NCRP)

• should be a main part of every health care facility’s personnel radiation control program

• ORP

ORP

optimization for radiation protection (ICRP)

cardinal rules- these principles can be applied to patient and technologist

• time

• distance

• shielding

  • can reduce exposure to both patient and radiography

alliance for radiation safety in pediatric imaging

partnership with overall purpose to reduce dose to pediatrics raise awareness among non-radiology professionals

image gently campaign

• 2008, alliance initiated campaign dissemination of pediatric CT dose reduction

• pause and pulse: image gently in fluoroscopy campaign- initiated to reduce dose in fluoroscopy procedures; using low dose pulsed fluoro

image wisely

• 2009, ACR and RSNA formed Joint Task Force on Adult Radiation Protection to address concerns about increases of public exposure to ionizing radiation

• objective of lowering the amount of radiation used in medically necessary imaging studies and eliminating unnecessary procedures

patient education

• explain procedure- what cooperation is needed to complete the study

• explain what if anything, needs to be done as a follow up to the exam

• patient active participant- make your patient feel like an active participant in their health care

• answer questions about the potential risks of the radiation to reduce fears and anxiety

BERT- background equivalent radiation time

• compares the amount of radiation received during a specific procedure to the amount of natural background radiation over a certain period of time

• helps explains exposures to patients

• educates and reduces anxiety

• does not imply radiation risk; it is a means for comparison

• emphasizes to patient that radiation is an innate part of the environment

• provides a more comprehendible answer to patient

• is NOT a radiation quantity; it is a method

radiographic dose documentation

dictating dose exposures and/ or fluoro time into radiology reports

radiation

the emission of energy in the form of electromagnetic waves or as moving subatomic particles passing through space from one location to another (protons, neutrons, beta particles)

Types of radiation

• mechanical vibration- which causes sound (ultrasound)

• electromagnetic wave-radio, microwaves, visible light, x-rays

electromagnetic spectrum

the full range of frequencies and wavelengths of electromagnetic waves

ionizing radiation

• examples: x-rays and gamma rays

• UV rays with GREATER energy than 10eV

• high energy, high frequency= short wavelength that transfers energy and ejects electron from atom

• foundation of x-rays and human tissue interactions

• valuable for imaging, but potential to cause harm (biological damage)

nonionizing radiation

• examples: infrared rays, microwaves, radiowaves

• UV rays LESS than 10eV

• lower energy, lower frequency= longer wavelength

• does not have enough kinetic energy to eject electrons from atoms

natural or background radiation

50%

Terrestial

• from crust of earth- radioactive material

• depends on- composition of soil or rocks (mountainous areas are higher)

  • examples: uranium, radium, thorium

radon definition

highest contributor of natural background radiation- colorless, odorless, radioactive gas present in the air

radon/thoron

• 2.3 mSv of natural

• free agent floating around in the soil

• most significant contributor

radon

• higher levels in soil that contains: granite, shale, phosphate, and pitchblende

• enters buildings through cracks or holes in the framework

• present in building materials such as : bricks concrete and gypsum wallboard

• higher in cooler months

• causes serious health issues- emits alpha radiation

• 2nd leading cause of lung cancer per EPA

• 20,000 deaths in US in a year

• EPA recommendations: homes to have annual levels no greater than 4 pico curies per liter of air 4pCi/L

  • 1 in 15 homes in US is above limits

cosmic radiation

• interaction with the: sun (solar), beyond solar system (galactic)

• greatest intensity occurs at high altitudes lower intensity occurs at sea level

internal radiation

• part of human metabolism

• radioactive atoms that make up small percentage of the body tissue

  • ingested

  • inhaled

  • exists in small quantities within the body

human-made radiation (50%)

• consumer product examples: early TVs, airport surveillance, ionizing smoke detectors, some timepieces with luminous dials, video display terminals, shoe fitting fluoroscopes, dentures

• air travel

• nuclear fuel- for generation power

• atmosphere fallout- from weapon testing

• nuclear accidents

TMI (1979)

Three Mile Island Unit 2 (TMI-2)

Chernobyl (1986)

• thyroid cancer in adolescents and children

• increase in breast cancer

• leukemia

most recent Nuclear plant accident

Fukushima (2011)

medical radiation types

• diagnostic machines

• radiopharmaceuticals/radioisotopes

X-rays were invented

• date: november 8, 1895

• by: wilhelm c. roentgen

first clinical x-ray in US

• date: February 1896

• by: Dr. Gilman frost and professor Edwin frost

• image was of: a boy’s broken wrist

first radiation induced death in US

• year: 1904

• who: clarence madison dally

what did edison invent?

fluoroscope

first cancer from occupation exposure to a physician

• year: 1910

radiodermatitis

reddening of the skin from radiation exposure resulted in cancer

aplastic anemia

a blood disorder, bone marrow failure

leukemia

abnormal overproduction of white blood cells (WBC)

1921 British x-ray and radium protection committee

set up guidelines to reduce occupational injury

1925 International Commission on radiation Units and Measurements formed

• defined ‘roentgen’ as a unit of exposure in 1928

• ‘roentgen’ accepted as a dose unit, but not clearly defined

1925 First International congress of radiology (second met in 1928)

• allowed radiologists all over the world to collaborate

• no definite decisions made for quantifying effects of radiation

1935- 1950s

1. 1937 ‘roentgen’ was internationally adopted as a unit of measurement for exposure

2. the US advisory committee on x-ray and radium protection became NCRP in 1946: national committee on radiation protection

3. 1948 international system of units (SI) established interchange units through all branches of science; traditional and SI

Skin erythema dose

• unit measuring radiation exposure 1900-1930s

• “quantity received that causes redness after irradiation”

• today is considered ‘absorbed dose’ and measured in gray (Gy)

tolerance dose

• dose to which occupational exposed individuals could be subjected without any apparent harmful acute effects; also threshold dose

• unit specified as Roentgen; 0.2 roentgen/day

• 1936- reduced tolerance dose to 0.1 roentgen/day

  • this was due to late tissue interactions and stochastic effects; potential harm to cause genetic and hereditary effects

maximum permissible dose (MPD)

• replaced tolerance dose in 1950s

• largest dose of ionizing radiation an occupationally exposed person allowed in a period, some small risk could still exist

• originally expressed in rem (radiation equivalent man or Roentgen equivalent man); replaced with the SI unit- sievert now

• “no amount of radiation is considered safe”

• occupational exposure based on comparison of other hazardous occupations

1970s radiation units developed for bioeffects of radiation types

• alpha, beta, gamma, x-ray and neutrons

• radiation effects depended on organ/system irradiated

• tissue weighting factors developed based on studies of epidemiology studies of atomic bomb survivors

• effective dose (EfD) adopted from this- measured in SI

exposure (X)

• total electric charge (+ or -) per unit mass that x-ray or gamma ray photons generate in air; based on response produced when radiation interacts with air

• “intensity of radiation delivered to specific area” such as human body

• used to measure tube output of imaging systems

• applies only with x-ray and gamma rays

• measured in: SI- coulomb/kilogram (C/kg)

air kerma (Gya)

• SI unit that can express how energy transfers from the beam to the air

• standard or free air ionization chamber is device to calibrate and measure

• measured in: SI unit: gray

• metric/traditional: joules/kg

air kerma can be used to describe

• tube input

• tube output

• exposure to skin

acronym KERMA

kinetic energy released in matter, air/material/ unit mass

entrance skin air kerma (ESAK) definition

dose index that is obtained from the center of the x-ray beam, using a calibrated electronic dose meter

absorbed dose (D)

• measures the absorbed patient dose

• ionizing radiation passing through object and stays in it

• the higher the atomic number the higher the absorbed dose

• responsible for biologic damage to the tissue exposure

• measured in Gray (Gy) or mGy

equivalent dose (EqD)

• product of average dose in human tissue or organs and it’s radiation weighting factor (Wr)

• measures the quantity of radiation received by radiation workers

• measurements:

  • SI unit- Sv or mSv

  • Traditional- rem

• radiation badge reports measured in rem

• conversion:

  • 1SV= 100 rems

  • 1SV= 1000 mSv

• EqD = D x Wr

ExCAGES

exposure → coulomb- absorbed dose → gray- equivalent dose → sievert

radioactivity (A)

• used to measure quantity of radioactive material

• not used in diagnostic x-ray

• measure in:

  • SI- becquerel (Bq)- named after french engineer and scientist (Antoine Henri Bequerel)

  • traditional- curie (Ci)- named after Pierre and Marie Curie

effective dose (EfD)

• measures overall risk of exposure to the patient from ionizing radiation

• takes into consideration type of radiation and radiosensitivity of the tissue

• uses tissue weighting factor Wr

• Measured in: SI or mSv

• can be used to compare the average amount of radiation received by the entire body from specific radiology exam with that from natural background radiation

collective effective dose (ColEfD) or (S)

• cumulative dose to a population or group exposed to a given radiation source or group of sources

• measured in person-sievert

DAP- dose area product

• a measure of the amount of radiant energy that has been delivered into a portion of the patient’s body surface

• takes into consideration the dose and the tissue exposed

• radiation dose to air x the area of x-ray field

• better indication of overall harm

Average effective dose (Eexp)

• effective dose to those exposed

• measured in millisievert

• calculated by dividing cumulative dose (S) of the individual by the total number of individuals exposed

  • excludes individuals NOT exposed from the specific source

effective dose per individual in US (Eus)

• dose per individual in the US population whether exposed to the source or not

  • measured in millisievert

• calculated by dividing cumulative dose (S) by the total number of individuals in US population

Somatic effect of radiation

• short term effect examples:

  • erythema, decrease in blood cells, CNS failure, disruption in GI structures and function

• long term/ late effect examples:

  • cancer, cataracts, shortening life expand, embryologic effects during 1st trimester

genetic effect of radiation

• damage to the cell’s genetic code/ DNA molecule

• effects seen in offspring of exposed individual

• exposure is received pre-conception in the sperm or ova

radiation can cause

excessive mutations

exposure

• number of ionizations (radiation) interacting with air

• tube output and leakage radiation from tube

• coulombs/kilogram (C/kGg)

Air Kerma (AK)

• how energy is transferred from beam of radiation to air

• x-ray tube input and output to IR

• mGy or mGy/min

what is the unit for exposure?

coulombs/kilogram

• C/kGg

• C/kg

what is the unit for air kerma?

mGy or mGy/min

what is the unit for absorbed dose

Gy or mGy

what is the unit for equivalent dose?

sievert (sV) or msv

what is the unit for collective effective dose (ColEfD) or (S)

person-sievert