Radiation Safety Training for Radiologic Technologists

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Radiation Safety Training for Radiologic
Technologists

• Associate Radiation Safety Officer

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

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

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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.

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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

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Radiation Biology

• Ionizing Radiation produces
• Free Radicals
• DNA damage
• All may result in death of cell or mutation of
  genetic information if not repaired

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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

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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

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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

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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.

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Background Radiation Sources
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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
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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

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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.

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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)

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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

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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.

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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.

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What are the different badges?

• Whole body
• Single dosimeter worn on the chest
• Chest
• Same as whole body badge, but worn on the chest
  underneath a lead apron, in combination with
  collar badge
• Collar
• Worn near the head, outside the lead apron, in
  combination with chest badge
• Extremity
• Ring badge

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What kind of badges will I get?

• It mostly depends where you work
• Radiology, Cardiac Cath, EP Lab
• Chest and collar
• Nuclear Medicine
• Whole body and extremity
• Nursing, Ancillary
• Whole body
• Other employees will have dosimetry to match
  their working environment

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How do I wear the badges?

• Whole body badge
• Wear on clothing or lab coat
• Chest badge
• Wear underneath lead apron
• Collar badge
• Wear outside lead apron near face
• Ring badge
• Wear on hand with label facing radiation source,
  underneath disposable gloves

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Proper Care of Badges

• Exchange badges promptly at the beginning of each
  monitoring period
• Take care not to reverse whole body and collar
  badges
• Do not leave badges on your apron, in the
  radiograph room, in direct sunlight, or near
  radioactive materials

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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.

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

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

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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

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Quarterly ALARA Levels
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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 exposures do not happen!

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Acute Radiation Syndrome

• The clinical symptoms of acute radiation doses
  follow a predictable course over time.
• The syndrome is characterized by the development
  of signs and symptoms.
• The time of symptom onset may help to indicate
  the dose.

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Early Somatic Effects

• 0 25 rad no detectable effects
• 25 50 rads blood changes begin most people
  no effects. Some may exhibit nausea or anorexia
• 200 rads Hemopoietic syndrome. Nausea in a few
  hours epilation in 2-3 weeks death possible
  within months.
• 400 rads complete ablation of bone marrow

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Early Somatic Effects contd

• 700 rads LD 50/30 days
• 1,000 rads GI syndrome vomiting, diarrhea,
  death in 1-2 weeks
• 2,000 rads CNS syndrome unconscious in
  minutes. Death within days.

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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, no effect is expected.

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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

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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)

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Diagnostic X-ray Techniques

• Radiographs
• Fluoroscopy
• Computed Tomography (CT)

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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

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

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

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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

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

• Dont catch the edge of the patient.

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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.
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Reduce Magnification when possible
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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.

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

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Operators Responsibilities

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

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Annual Survey

• The State of Georgia requires annual survey of
  all radiation producing equipment
• Survey includes radiation output and scatter
  chart
• Data posted near machine
• All new equipment must be surveyed prior to use

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Radiation Injury from Fluoroscopy

• A delay of weeks often occurs between irradiation
  and recognizable symptoms of injury, shorter
  delays also occur
• This delay results in a lack of association on
  the parts of physicians and patients between the
  fluoroscopy and the injury

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Procedures Associated With Injury

• Coronary angioplasty
• Renal angioplasty
• Uterine embolization
• TIPS placement
• Radiofrequency ablation
• Neuroembolization

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Radiation Injury from Fluoroscopy

• Patients are often unaware that fluoroscopy
  procedures use x rays and are usually totally
  unaware that fluoroscopy can cause injury
• Physicians are often unaware that fluoroscopy can
  cause injury
• Physicians are often poorly trained in dose
  management

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Factors Associated with Injury

• Long procedures with fluoroscopy on-times over
  the same skin area
• Fluoroscopy through thick body parts (steeply
  angled projections and/or large patients)
• High dose rate modes of operation
• No dose monitoring devices

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Factors Associated with Injury

• Multiple procedures
• Poorly designed equipment
• Unnecessary body parts in direct radiation field
• Radiation-sensitive patients (collagen vascular
  diseases, hyperthyroidism, certain medications)

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Threshold skin entrance doses for different skin
injuries (Data adopted from Wagner, Eifel and
Geise, 1994 and modified on data from John
Hopewell, oral communication, 1999).
d day(s) wk week(s) yr year(s)
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Example of Fluoro Output EUH Cardiac Cath Lab 4
(measured in 2004)

• Time to deliver 100 rads to patient at max.
  normal output
• Frontal 10 minutes, 48 seconds
• Lateral 12 minutes, 39 seconds
• Time to deliver 100 rads to patient at max.
  output with boost
• Frontal 9 minutes, 51 seconds
• Lateral 11 minutes, 25 seconds

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Cine Output Cath Lab 4(Note that output has
increased by factor of 2 to 17!)
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4 mos after procedures
7 mos after procedures
9 mos after procedures
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 mos after procedures
22 mos after procedures
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Several months after 3rd angioplasty
5 months after third angioplasty
22 months after third angioplasty
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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.
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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

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FDA Recommendations

• Record data into the patients medical record
• Identify areas of patients skin that received
  the dose
• Record total fluoro time which room was used

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After the Procedure

• Record fluoro time and projection in patient
  chart, especially for interventional procedures
  lasting longer than 15 minutes
• Indicate in which room procedure occurred
• Record any additional information on radiation
  output