Transcript Slide 1

Radiation Safety Office
306 Benson School
X-RAY SAFETY TRAINING:
The Safe Use of Fluoroscopy
Safety information required for
persons who work with or near the
fluoroscopy unit in Animal Care
Why Training?
• “Rules and Regulations for Radiation Control” Title
B (X-rays). Enforced by SC Department of Health &
Environmental Control (SC DHEC)- 4.12.22- Operator
Requirements for veterinary X-ray.
• The safety of the operator and others in the room
depends on good practices!!
Training Plan
• Basic characteristics of x-radiation.
• Identify types of fluoroscopic units and potential
hazards associated with equipment.
• Biological Effects and Units of dose
• Personnel monitoring
• Specific Safety for the Fluoroscope
• Applicable State Regulations
• Written operating procedures
• Actual operation of the unit (PI requirement)
Radiography vs. Fluoroscopy
• Radiographs are “pictures” of the internal structures
where X-rays pass through the body and make an
image on film or digitally - one image at a time.
• Fluoroscopy allows the visualization of movement in
the internal structures in real time. The fluoroscopic
image is formed on an image intensifier (II) and
displayed on a video screen. X-rays are “continuous”
as long as the operating switch is on.
Basics Of X-Ray Production
Radiographs and Fluoroscopy both
use ionizing radiation.
Characteristics of X-rays
• A form of electromagnetic energy that is generated
by an X-ray source/machine.
• Invisible
• Due to the energy of the X-rays, they can penetrate
the body. They are absorbed more by denser
material (bone) than softer tissue. This difference
leads to an image of varying light/dark shades where
internal structure can be seen.
Electromagnetic (EM)
Waves or photons:
The electromagnetic spectrum covers a wide range of wavelengths and photon
energies. It includes visible light, Radio waves, Microwaves, UV light, X-rays and
gamma rays. An excited atom can emit an X-ray or gamma ray to get back to a
ground state. The only difference is where the wave originates.
• Gamma Rays ()- emission of EM from the nucleus to get an atom back to a
ground state.
• X-Rays- Originate from outside the nucleus in electron cloud.
Ionizing Radiation
• Ionizing radiation has enough energy to remove tightly bound
electrons from atoms, and will create Ions.
• When this ionization occurs in living cells, there could be
some consequences to the cells and tissues in the body,
depending on the amount of radiation. The cells could either
die, repair themselves, or become mutated in some form and
become cancerous.
• There are many variables to the effect the radiation will
produce.
• Because X-rays are considered ionizing radiation, there is an
attempt to reduce any unnecessary exposure.
Generating X-rays
• X-rays are generated in a vacuum tube.
• Electrons from a cathode accelerate under high
voltage towards an anode.
• When the electrons hit the anode they slow down
abruptly and generate X-rays in the process.
• The X-rays escape out of a window in the tube and
become useful.
X-ray Tube Design
X-ray Technique
• The energy of the X-rays is determined by the voltage
applied to the anode (commonly called the
kilovoltage or kV).
• The intensity of the X-rays is determined by the flow
of electrons from the cathode to the anode.
• The electron flow is often called the mAs (for
milliamp-second).
• Together the kV and mAs make up the X-ray
technique.
X-ray Technique- kV
• The kV determines how much energy gets through
the subject.
• Use high kV to penetrate bone, large people, or large
boney people.
• Use low kV to show soft tissues, such as heart and
lung.
• kVs range from about 25 kV for mammography to
150 kV for chest X-rays.
• Typical fluoroscope kVs are in the 50 kV to 80 kV
range.
X-ray Technique- mAs
• The mAs determines the total amount of radiation
used to make an image.
• In a conventional X-ray the time (s) is very short and
the tube current (mA) is fairly large.
• Fluoroscopy uses a small mA, but exposures may run
for several seconds.
• The result is a moving, but grainy image.
X-ray Technique- kV and mA
• Typically, the kV is set to penetrate the chosen body
part, and the mA is adjusted to give a suitable image.
• In fluoroscopy this procedure is usually done
automatically in a process called auto-fluoro.
The Fluoroscopic Unit
Fluoroscopic Images
Compared to conventional X-ray images, fluoroscopic
images are grainy.
• Fluoroscopy images use as little radiation as possible.
• Less radiation = more noise (image grain)
• More noise = harder to see fine detail.
Fluoroscopy is used for examining large structures or
those filled with a contrast agent. Fine image
resolution usually not necessary.
Type of Fluoroscopes
• General purpose fluoroscopes may have the X-ray
head under or over the table.
• Over-table units can be used for general radiology as
well.
• The image intensifier (II) on an under-table unit is
called the tower.
Stationary Fluoroscopes
X-ray Head
Image
Intensifier
Undertable Fluoro
Overtable Fluoro
Other type of Fluoroscopes
A C-arm is an x-ray unit with the support structure
shaped like the letter “C” between the x-ray tube and
the image intensifier. The C-arm permits the physician
to rotate and angle the x-ray tube without moving the
patient.
- Mobile C-arms can roll around.
- Mini C-arms are smaller fluoroscopes used only for
extremities.
C-ARMS
• Mobile C-Arm
• Mini C-Arm
Safety Considerations
• It is sometimes difficult to use distance to reduce exposurestaff exposure with C-arms can be a problem.
• Training for all personnel in the room is a must.
• X-rays are produced only when the x-ray tube is energized- a
light indicates when X-rays are on.
• Never point the instrument at yourself or anyone when the
shutter is open.
• Scatter radiation from the subject can add to total exposure of
personnel in the room.
• Personnel shielding is critical!
Where do you stand during
fluoroscopy use?
• Scattered radiation from the patient is the main
source of exposure to staff in the room.
• Scatter radiation is more intense on the X-ray tube
side where the x-rays are being emitted.
• Personnel should stand on the image intensifier side
to reduce the exposure due to scatter.
Proper Positioning
• Whenever possible, position the X-ray head under
the patient. (This isn’t possible on an over-table
unit.)
• The X-ray source (inside the head) must be at least
12” away from the patient’s skin. This is built into
most fixed units. C-arms have spacer cones to keep
the right distance.
Use of Foot Pedals
• Fluoroscopes of all types are operated by the use of a
foot pedal. When the pedal is depressed, X-rays are
emitted.
• The pedal is a “dead man” switch. The machine will
only operate when there is pressure on the switch.
As soon as pressure is off of the switch, the X-rays
are no longer produced.
Image Intensifier
• The Image Intensifier (II) converts the X-ray image
into a video image. The image can be adjusted for
brightness and magnification to view the area of
interest.
• Brighter images require more radiation and possibly
more exposure to the operator and ancillary
personnel from scatter.
• The II may be a large vacuum device or a flat panel.
Image Intensifiers
Flat Panel
Tube device
Biological Effects from Ionizing
Radiation
Biological Effects
from large doses of radiation
• Radiation sickness
• Loss of hair
• Skin burns
• Tissue necrosis
• Death (if dose is high enough)
*Generally, these effects can only occur in very rare
instances.
Biological Effects
from small doses of radiation
• Carcinogenesis
• Genetic abnormalities in offspring
• Damage to developing fetus
* These potential effects are the main concerns with
any dose received from sources on campus.
Units of Radiation Dose
• Roentgen
• Radiation Absorbed Dose (RAD)
• Roentgen Equivalent Man (REM)
Roentgen (R)
• A measure of radiation exposure in air.
• 1R=2.58 x 10 -4 Coulombs/kg of air
• Used for measurement of X-rays and Gamma Rays
only.
Radiation Absorbed Dose
(Rad or Gray)
The amount of energy from ionizing radiation
deposited in any medium (water, tissue, air).
Absorbed dose is dependent on:
1. energy of the radiation
2. density of the medium
Radiation Equivalent Dose
(Rem or Sievert)
A measurement of the biological damage to living
tissue as a result of radiation exposure.
• absorbed dose (Rad)* Quality Factor (QF)
where QF is based on the type of radiation since some
types of radiation cause more biological damage than
others.
Rem (or Sievert)
Each type of radiation is assigned a quality factor:
•
x-rays = 1
•
gamma rays = 1
•
neutrons = 10-20
•
alphas = 20
In summary:
For x-rays, 1Rad = 1 Rem
For alphas, 1Rad = 20 Rem
Dose is usually expressed in millirem (mrem)
1 Rem = 1000 mrem
ALARA
Keep doses to employees
As Low As Reasonably Achievable
This is a radiation safety principle for minimizing
radiation doses and releases of radioactive materials by
employing all reasonable methods. ALARA is not only a
sound safety principle, but is a regulatory requirement
for all radiation safety programs.
Three methods of Reducing
Exposure
• Time: the less time spent near a radiation source, the less exposure.
With Fluoroscopy, the less time the X-ray beam is on, the lower exposure.
• Distance: Inverse Square Law applies to X-rays. The more distance
between you and the radiation source, the less exposure you will receive.
Double your distance and your exposure is decreased by a factor of 4.
• Shielding: A material that is placed between yourself and the radiation
source to absorb radiation. Lead is often used to shield x-rays. Personnel
shielding (apron, gloves, and thyroid collars) is used during fluoroscopy
procedures to reduce your exposure.
Specific Safety for Fluoroscopy
General Requirements for
Personnel
• All personnel in the room during procedures will wear a .5 mm lead
equivalent apron. Thyroid shields may also be required in some
instances.
• Always remember that the apron is not covering all parts of your
body.
• Personnel monitoring will be issued to personnel who need to be in
the room during procedures.
• Prior occupational dose (dose received while employed at another
facility) will be requested and documented.
• Doses from multiple facilities will be documented if you are
receiving exposure at a different job.
General Requirements for
Personnel
• Must have a training plan: initial training and annual
training by the PI.
• Training must include safety procedures, the machine
functions, and recognizing any problems with the
unit.
• Follow all safety procedures established for the X-ray
unit.
Holding of Animals- Safety requirements
• Holder will use leaded gloves in addition to a lead
apron.
• If possible, keep all body parts out of direct x-ray
beam.
• Keep as far away from x-ray beam as possible.
• Do not use the same person to hold animals
routinely.
• Staff under 18 not permitted and when practical,
pregnant workers should not hold an animal.
Personnel Monitoring
• Required by SC DHEC for those who may get 10% of
the occupational dose.
• Whole body badge placed on top of the lead apron
to get “worse case” exposure- The apron will reduce
the exposure to the area covered by the apron.
• Ring badge worn on hand that is most likely to get in
the x-ray beam. The ring badge is worn under the
leaded glove.
Personnel Dosimeters
• Wear them anytime you are using the x-ray device.
• Place badges where you think the maximum dose
will be found.
• Doses on dosimeter reports are in mrem. They will
be exchanged on a bimonthly basis.
• Don’t take badges home. Leave in an area where
they will not get accidently X-rayed.
• Never intentionally expose badges.
Personnel Dosimeters
• Don’t tamper with badges
• Don’t use badge when you are receiving an x-ray or
nuclear medicine study
• Protect device from heat or moisture
• Contact Radiation Safety Office if you leave USC or
change jobs
Personnel Dosimeters
Ring Badge
Whole Body
Annual Occupational Dose Limits
Because your work involves potential exposure to
radiation, you are classified as an occupational worker
and must receive training. As an occupational worker,
there are annual limits established.
• 5.0 Rem/yr (5000 mrem/yr) total dose from external
or internal exposures. You can only receive external
dose when working near an x-ray device.
• 15.0 Rem/yr (15000 mrem/yr) Dose to the eye.
Dose to Embryo/Fetus
• Declaration of pregnancy is voluntary- USC Radiation
Safety has a form which must be completed.
• If employee declares a pregnancy, an additional
badge must be worn under the apron to record dose
to the fetus.
• Dose limit per term (9 months) – 500 mrem
• Alteration of work activities may be possible.
• Pregnant workers should not hold animals during
fluoroscopic procedures.
Additional Requirements
• A “Caution- X-rays” sign must be posted on each door leading
into the X-ray suite.
• A “Notice to Employees” RHA-20 OSHA form must be posted
in the room which provides your rights as a radiation worker.
• The measurement of the fluoroscopic output is required
annually and must be posted on the control. It must include
the name of the person who measured the output and the
date conducted.
• All requirements are based on the State of South Carolina
Regulations for Radiation Control- Title B.
Records to Maintain
•
•
•
•
Records showing model & serial numbers of instrument(s)
Copies of all correspondence with SC DHEC.
Annual calibration measurement/surveys.
Personnel Monitoring reports- must be accessible to all
personnel who are badged.
• Training records- Initial (provided through Radiation Safety)
and Annual Refreshers (provided by the PI).
• A written Operating Procedure which includes the general
function of the fluoroscopic unit, safety precautions in place,
use of personnel shielding, animal holding procedures,
declaration of pregnancy policy, and use of personnel
monitoring.
Examination Information
• Call 777-5269 for appointment or you may Email
[email protected] to schedule a time for the
Fluoroscopic Safety exam.
• Bring:
(1) pen or pencil
(2) bring student/staff ID or driver’s license
• Directions to Benson School: go to www.sc.edu/visit/map/
enter “Benson School”.
THANKS FOR PARTICIPATING IN
THIS TRAINING CLASS
If you have any questions related to
radiation safety, please contact us at:
777-5269