Radiation Safety Training for Medical Imaging Students

1
Radiation Safety Training for Medical Imaging
Students

• Deputy Radiation Safety Officer

Michael Ike Hall, CHP, CSP Emory University
Hospital 404-712-7867
2
Topics

• Fundamentals of Radiation
• Radiation Limits and Dosimetry
• Biological Effects of Radiation
• Radiation and Pregnancy
• Fluoroscopy and Patient Injuries
• Worker Protection

3
What is radiation?

• Radiation is energy emitted from unstable atoms.
  Radiation can be in the form of subatomic
  particles (alpha or beta particles) or
  electromagnetic radiation (X and gamma rays).
  Radiation that is energetic enough to change the
  chemistry of a target is called ionizing
  radiation, and that will be the focus of this
  training.

4
Ionizing Radiation

• Ion atom with a positive or negative charge
  (i.e., too few or too many electrons)
• Radiation that is energetic enough can strip
  electrons and create ions
• Ionization can change molecular chemistry or
  break apart molecules

5
Radiation Biologyin a nutshell

• Ionizing radiation harms biological systems by
  two means
• Indirectly - Production of Free Radicals
• Directly - DNA damage

6
Four Possible Outcomes

• Cells are undamaged by the dose
• Cells are damaged, repair the damage and operate
  normally
• Cells are damaged, repair the damage and operate
  abnormally
• Cells die as a result of the damage

7
Measuring Radiation

• Exposure measure of ionization in air (roentgen,
  or R)
• Absorbed dose energy deposited in material per
  unit mass (Gray or rad)
• 1 Gray 1 Joule/kg 100 rad

8
Measuring Radiation

• Equivalent dose measure of the biological effect
  of a specific kind of radiation on humans
  (Sieverts or rem)
• For x-rays, dose and dose equivalent are equal.
  Dose equivalence may be different for some
  radioactive particles.
• 1 Gray 1 Sievert 100 rem

9
How much radiation is harmful?

• Radiogenic health effects (primarily cancer) are
  observed in humans only at doses in excess of 10
  rem delivered at high dose rates. Below this
  dose, estimation of adverse health effect is
  speculative.
• Radiation Risk in Perspective
• Health Physics Society

10
How much radiation is in the environment?

• People are exposed to background radiation
  continuously.
• The average dose due to background exposure is
  around 350 millirem per year in the United
  States.
• Background exposure can vary with altitude, soil,
  and medical usage.

11
Background Radiation Sources
12
Terrestrial Radiation
Even the highest known levels of background
radiation have not proven to increase the risk to
residents.
units in mGy/year Terrestrial radiation only
13
Radiation Safety Principles

• The Radiation Safety program, including
  training, monitoring, and contamination control,
  is designed to ensure that no worker receives a
  radiation dose in excess of regulatory limits,
  and that each worker generally receives only as
  much exposure as necessary to do one's job.

14
Radiation Safety Principles

• Time
• Distance
• Shielding
• Containment

15
Time

• Dose is directly proportional to the time spent
  near radiation and radioactive materials
• Minimize time near radiation producing machines
  and radioactive materials or patients whenever
  possible
• Plan work activities so as to spend less time
  handling radioactive material

16
Distance

• Inverse square law radiation exposure is
  inversely proportional to the square of the
  distance

17
Distance

• Maximize your distance from radiation-producing
  machines and radioactive materials or patients
• Use tongs or other tools to handle radioactive
  sources
• Move radioactive materials using a cart or
  portable lead pig

18
Shielding

• Use the right kind of shielding for the radiation
  in question
• Beta radiation Plexiglas
• Gamma and x-ray Lead or other high-density
  material
• Use sufficient shielding for the task

19
Shielding

• Engineering controls leaded walls, windows,
  movable barriers, bricks, shipping and storage
  containers
• PPE Lead aprons, thyroid collars, and glasses
  for radiation-producing equipment

20
Containment

• Engineering controls Sealed sources, syringe
  caps, ventilation
• PPE Disposable gloves, lab coats, isolation
  gowns, booties, goggles, face shields, coveralls,
  respirators
• Routine contamination monitoring is essential to
  verify proper containment of radioactive materials

21
Annual Occupational Limits

• 5000 mrem whole body
• 15,000 mrem to lens of eye
• 50,000 mrem to extremities
• Set by federal government based on advice from
  scientific committees

22
Are these limits safe?

• The annual radiation limits have been
  established to ensure that the long-term risks of
  radiation exposure are minimized. There has been
  no evidence that occupational doses within these
  limits pose any risk. Due to potential
  uncertainties in dose measurement, the limits are
  set conservatively.

23
Other Dose Limits

• Members of public limited to 100 mrem per year
  from licensed activities, 500 mrem per year from
  exposure to Nuclear Medicine therapy patients
• Employees under 18 limited to 10 of permissible
  adult dose limit (500 mrem annually)

24
Declared Pregnant Workers

• 500 mrem/term limit to fetus (50 mrem/month)
• Limit is extremely conservative with respect to
  risk
• Contact supervisor and Radiation Safety Officer
  to declare pregnancy
• Monthly fetal badge assigned

25
Who gets radiation badges?

• Radiation badges are required for workers who
  are likely to receive more than 10 of the annual
  occupational radiation limits.
• In practice, almost everyone who routinely works
  with radioactive materials or radiation-producing
  machines gets one or more badges.

26
How do I request a badge?

• Ask your supervisor or the Radiation Safety
  Officer for a Personnel History Form. You may
  also find the form online.
• Radiation Safety Training is required to get a
  badge. Please ask your supervisor or the RSO.
  Training may be provided as an orientation
  packet, an inservice, or online.

27
Dosimetry

• Wear chest badge under lead apron on chest
• Wear collar badge outside lead apron
• Extremity dosimetry (rings and wrist badges) must
  conform to Infection Control requirements

28
Proper Care of Badges

• Actually take them out of the package and wear
  them
• Take care not to reverse chest and collar badges
• Do not leave badges on your apron or in the suite
• Exchange badges promptly at the beginning of each
  month or pay 20

29
How does the badge work?

• The Luxel dosimeter has a thin strip of
  specially formulated aluminum oxide (Al2O3)
  crystalline material. Filters of various
  thickness simulate radiation doses to different
  tissues. During analysis, the strip is stimulated
  with laser light, causing it to luminesce in
  proportion to the amount of radiation exposure.

30
Annual Occupational Limits

• 5000 mrem whole body
• 15,000 mrem to lens of eye
• 50,000 mrem to extremities
• Set by federal government based on advice from
  scientific committees

31
Other Dose Limits

• Members of public limited to 100 mrem per year
  from licensed activities, 500 mrem per year from
  exposure to Nuclear Medicine therapy patients
• Employees under 18 limited to 10 of permissible
  adult dose limit (500 mrem annually)

32
Dosimetry Reports

• Dosimetry reports provided monthly to
  departmental contact
• Emory maintains permanent record, department
  maintains for 3 years
• Review and initial dosimetry reports
• Report dosimetry problems to supervisor or
  Radiation Safety Officer

33
So, how do I read one of these things?
34
Your name and participant number are listed in
the first column. The date of the badges on the
report is shown above.
35
The badge types on the report are listed here.
Most Radiology workers have chest and collar
badges.
36
The first number is the deep dose, the dose to
the whole body from penetrating radiation (1 cm
tissue depth)
37
The next number is the eye dose, the dose to the
lens of the eye (0.3 cm tissue depth)
38
The last number is the shallow dose, the dose to
the dermal layer (0.007 cm tissue depth)
39
The report also has quarterly, annual, and
lifetime accumulated totals.
40
Dose Determination

• For workers with chest and collar badges,
  assigned dose is a combination of readings
• Whole body dose from a combination of chest and
  collar badges
• Eye dose from lens-equivalent area of collar
  badge
• Shallow dose from skin-equivalent area of collar
  badge

41
Quarterly ALARA Reports

• Workers exceeding the doses on the following
  table are added to the ALARA report
• ALARA Level 2 doses are investigated by the
  Radiation Safety Officer
• Work activity may be restricted if corrective
  actions not taken

42
Quarterly ALARA Levels
Dose Level 1 Level 2
Whole Body ? 125 mrem ? 375 mrem
Collar ? 400 mrem ? 1200 mrem
Lens of Eye ? 375 mrem ? 1125 mrem
Skin ? 1250 mrem ? 3750 mrem
Extremities ? 1250 mrem ? 3750 mrem
43
What are the effects of high doses of radiation?

• Acute radiation exposure, however rare, may
  result in severe clinical effects or even death
• Exposures of minutes to hours while handling
  highly radioactive sources
• Laboratory and manufacturing accidents
• Intentional and accidental high medical doses
• Radiation controls are in place to ensure that
  these kinds of exposures do not happen!

44
Category of Effects

• Deterministic effects occur with acute doses and
  result from cell death
• Characterized by threshold dose (below a given
  dose, no effect)
• Stochastic effects may occur at chronic doses
• Affects the probability of all-or-none phenomena
  such as carcinogenesis
• Ill-defined threshold dose

45
Acute Radiation Syndrome

• Follows a predictable course over a period of
  time
• Characterized by the development of signs and
  symptoms
• Onset time of symptoms indicates dose
• Severity of effect increases as dose increases

46
ARS Syndromes

• Bone marrow syndrome (a.k.a. hematopoietic
  syndrome)
• Full syndrome between 0.7 and 10 Gy
• Milder symptoms may occur as low as 0.3 Gy
• Gastrointestinal (GI) syndrome
• Full syndrome gt10 Gy
• Milder symptoms may occur as low as 6 Gy
• Cardiovascular (CV)/ Central Nervous System (CNS)
  syndrome
• Full syndrome gt50 Gy
• Some symptoms may occur as low as 20 Gy

47
Bone marrow syndrome

• The survival rate of patients decreases with
  increasing dose
• Characterized by damage to cells that divide at
  the most rapid pace (such as bone marrow, the
  spleen and lymphatic tissue)
• The primary cause of death is the destruction of
  the bone marrow, resulting in infection and
  hemorrhage

48
Gastrointestinal (GI) syndrome

• Survival is extremely unlikely with this syndrome
• Destructive and irreparable changes in the GI
  tract and bone marrow usually cause infection,
  dehydration, and electrolyte imbalance
• Death usually occurs within 2 weeks

49
Cardiovascular (CV) / Central Nervous System
(CNS) syndrome

• Death typically occurs within 3 days
• Death likely is due to collapse of the
  circulatory system as well as increased pressure
  in the confining cranial vault as the result of
  increased fluid content caused by edema,
  vasculitis, and meningitis.

50
Four Stages of ARS

• Prodromal stage (N-V-D stage) Classic symptoms
  are nausea, vomiting, as well as anorexia and
  possibly diarrhea, which occur from minutes to
  days following exposure. The symptoms may last
  (episodically) for minutes up to several days.
• Latent stage Patient looks and feels generally
  healthy for a few hours or even up to a few weeks.

51
Four Stages of ARS

• Manifest illness stage Symptoms depend on the
  specific syndrome and last from hours up to
  several months.
• Recovery or death Most patients who do not
  recover will die within several months of
  exposure. The recovery process lasts from several
  weeks up to two years.

52
Effects on Embryo / Fetus

• High acute doses may cause death or abnormalities
• Large doses between 4 11 weeks can cause severe
  abnormalities
• Doses as low as 25 rad may cause defects
• Doses less than 10 rad generally considered not
  to increase risk

53
Patients and Pregnancy

• Mandatory patient pregnancy testing for high dose
  procedures
• Screening permitted for low dose diagnostic
  procedures
• Report cases of fetal exposure to supervisor and
  Radiation Safety Officer IMMEDIATELY
• RSO will determine fetal dose and report to
  patients physician

54
Cutaneous Radiation Syndrome (CRS)

• Recently introduced to describe the complex
  pathological syndrome that results from acute
  radiation exposure to the skin.
• It is possible to receive a damaging dose to the
  skin without symptoms of ARS, especially with
  acute exposures to beta radiation or X-rays.

55
Cutaneous Radiation Syndrome (CRS)

• Cause of syndrome is radiation damage to basal
  cell layer of the skin
• Characterized by inflammation, erythema,
  epilation, and/or dry or moist desquamation
• Within a few hours after irradiation, a transient
  and inconsistent erythema (associated with
  itching) can occur
• A latent phase may occur and last from a few days
  up to several weeks, when intense reddening,
  blistering, and ulceration of the irradiated site
  are visible

56
Cutaneous Radiation Syndrome (CRS)

• In most cases, healing occurs by regenerative
  means however, very large skin doses can cause
  permanent hair loss, damaged sebaceous and sweat
  glands, atrophy, fibrosis, decreased or increased
  skin pigmentation, and ulceration or necrosis of
  the exposed tissue.

57
How much radiation does it take to injure skin?
SKIN EFFECT Single-Dose Threshold (Gy) Onset
Early transient erythema 2 Hours
Main Erythema 6 10 d
Temporary epilation 3 3 wk
Permanent epilation 7 3 wk
Dry desquamation 14 4 wk
Moist desquamation 18 4 wk
Secondary ulceration 24 gt6 wk
Late erythema 15 6 10 wk
Ischemic dermal necrosis 18 gt10 wk
Dermal atrophy (1st phase) 10 gt14 wk
Dermal atrophy (2nd phase) 10 gt1 yr
Induration (Invasive Fibrosis) 10 gt1 yr
Telangiectasia 10 gt1 yr
d day(s) wk week(s) yr year(s)
58
4 months after procedures
7 months
9 months
Three TIPS procedures in 1 week in type II
diabetic. Total procedure time 13 - 16 hours.
Three weeks later noticed 13-cm x 17-cm mottled
oval discoloration on back. Initially diagnosed
as strep infection, then as herpes I, then as
allergic reaction to oral diabetic medications.
Diagnosis of radiodermatitis obtained ten months
after procedure!
23 months
22 months
59
Several months after third angioplasty
5 months
22 months
60
Surgical flap
At 3 wks
At 6.5 mos
Following ablation procedure with arm in beam
near port and separator cone removed. About 20
minutes of fluoroscopy.
61
Stochastic Effects

• The effects of low levels of radiation are more
  difficult to determine because the deterministic
  effects described above do not occur at these
  levels.
• Studies of people who have received high doses
  have shown a link between radiation dose and some
  delayed, or latent effects, including some forms
  of cancer and genetic effects.

62
Stochastic Effects

• To estimate the risks associated with low or
  chronic exposure, we create a model of the risk
  of occurrence of cancer at high doses to the risk
  of cancer at low doses, usually assuming no
  threshold. This type of risk model is called
  stochastic. The risk of a clinical effect
  increases with the dose, but the effect is the
  same.

63
Stochastic Effects

• This scaling or extrapolation is generally
  considered to be a conservative approach (may
  over-estimate the risk) to estimating low-dose
  risks.
• The risk of certain effects, including cancer,
  may be cumulative in patients with repeated
  examinations and higher in younger patients.

64

Estimated Days of Life Expectancy Lost From Various Risk Factors Estimated Days of Life Expectancy Lost From Various Risk Factors
Industry Type or Activity Estimated Days of Life Expectancy Lost
Smoking 20 cigarettes a day 2370 (6.5 years)
Overweight by 20 985 (2.7 years)
Mining and Quarrying 328
Construction 302
Agriculture 277
Government 55
Manufacturing 43
Radiation - 340 mrem/yr for 30 years 49
Radiation - 100 mrem/yr for 70 years 34

65
Ionizing Radiation at EUH

• Radiography
• Fluoroscopy
• Computed Tomography (CT)
• Nuclear Medicine
• Diagnostic
• Therapeutic
• Radiation Oncology
• Blood Irradiation

66
How are X-rays produced?

• Electrons are fired at a target made of a heavy
  material, like tungsten
• The electrons are slowed down by the nuclei of
  the tungsten atoms
• Some of the electron energy is converted to
  electromagnetic radiation (x-rays)

67
(No Transcript)
68
Diagnostic X-ray Techniques

• Radiographs
• Fluoroscopy
• Computed Tomography (CT)

69
How do I reduce my exposure?

• Observe the following precautions
• Maximize your distance from radiation producing
  machines whenever practical
• Do not be in the suite longer than necessary
• Utilize available shielding

70
Use Available Shielding
Leaded Goggles, if necessary Thyroid
Shield Badges Lead vest apron Wear dosimetry!
71
Use Available Shielding

• Adjustable head/neck shields
• RADPAD patient drapes
• Leaded acrylic barriers and windows

72
Distance

• Know room geometry
• NEVER PUT UNPROTECTED HANDS IN BEAM

72 mR/hr 21 mR/hr
(1) (2) (3) (4)
(5) 106 mR/hr 32 mR/hr
3 mR/hr  

1. 20cm from scattering object
2. 30 cm
3. 40 cm
4. 50 cm
5. 1 m

73
Keep Image Intensifier Close to Patient
74
Collimate to the Area of Interest

• Dont catch the edge of the patient.

75
Keep X-Ray Tube Below Patient
The patient is the source of the scattered
radiation in the x-ray suite. The spacer
provides a minimum safe distance to the patients
skin from the x-ray tube.
76
Reduce Magnification when possible
77
Be Aware of Patient Thickness

• When using automatic brightness, larger
  patients will have a higher radiation exposure
  for the same image quality as a thinner patient.
  Avoid oblique angles when possible.

78
Thick Oblique vs Thin PA geometry
Dose rate 20 40 mGyt/min
80 cm
100 cm
79
Operators Responsibilities

• Notifying the RSO when there is a new machine or
  any change in setup
• Keeping exposures to himself staff ALARA
• Clearing the area of all nonessential personnel

80
Operators Responsibilities

• Observing any restrictions
• Using minimum exposure factors
• Notifying your supervisor and the RSO immediately
  of any accidental exposure to radiation

81
FDA Recommendations

• Establish standard procedures and protocols
• Determine dose rates for specific systems
• Assess each protocol for the potential for
  radiation injury to the patient
• Modify protocols to minimize cumulative absorbed
  dose to any skin area
• Appropriate training for all operators

82
After the Procedure

• Record fluoro time and projection in patient
  chart, especially for interventional procedures
  with more than 30 minutes of beam-on time
• Indicate in which room procedure occurred
• Record any additional information on radiation
  output