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Radiation Safety Training for Medical Imaging Students

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Radiation Safety Training for Medical Imaging Students Deputy Radiation Safety Officer: Michael Ike Hall, CHP, CSP Emory University Hospital – PowerPoint PPT presentation

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Title: 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 Biology in 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
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?
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


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  
  • 20cm from scattering object
  • 30 cm
  • 40 cm
  • 50 cm
  • 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
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