Radiation Safety

1. Radiation Safety Training

2. What is Radiation?
• Radiation is energy in the form of particles
or electromagnetic waves.
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3. What is Ionizing Radiation?
• Ionizing radiation is defined as radiation
consisting of particles, X-rays, or gamma
rays with sufficient energy to cause
ionization in the medium through which it
passes.

4. Radioactivity
• The process by which
unstable atoms
spontaneously
transform to new
atoms* and in the
process emit radiation.
*The “new atom” may be the same atom in a
lower energy state.

5. Naturally Occurring Radiation in your Body
Nuclide Activity .
Uranium 30 pCi (1.1 Bq)
Thorium 3 pCi (0.11 Bq)
Potassium 40 120 nCi (4.4 kBq)
Radium 30 pCi (1.1 Bq)
Carbon 14 0.4 µCi (15 kBq)
Tritium 0.6 nCi (23 Bq)
Polonium 1 nCi (37 Bq)

6. Radiation Definitions
• Exposure R (roentgen): Amount of charge
produced per unit mass of air from x-rays and
gamma rays.
• Absorbed Dose rad: Amount of Energy deposited
per unit mass of material. 1Gy = 100 rad.
• Dose Equivalent rem: Risk adjusted absorbed
dose. The absorbed dose is weighted by the
radiation type and tissue susceptibility to biological
damage. 1 Sv = 100 rem.
• Radiation weighting factors: alpha(20), beta(1), n(10).
• Tissue weighting factors: lung(0.12), thyroid(0.03), and
gonads(0.25).

7. * Helium Nucleus – Very massive and doubly ionized
* Only a hazard via ingestion or inhalation of alpha emitter
* Not usually an external radiation hazard
* Stopped by paper and dead layer of skin
* Uranium, Thorium, Radon and radon daughters
Alpha Decay

8. Energetic electron – singly ionized
External hazard to skin and eyes
Internal hazard via ingestion or inhalation of beta emitter
Produces bremsstrahlung radiation
A 1 MeV beta can travel up to 12 feet in air and 1 cm in
plastic
Phosphorus, Tritium, Carbon, Sulfur
BETA DECAY

9. Gamma Decay
* X-rays and gamma rays are photons – no charge
* External radiation hazard to deep organs and tissues
* Internal hazard via ingestion or inhalation of gamma emitter
* Lead (high electron density) is good for shielding x and gamma rays
* Iodine 125 gammas (30 keV) can be easily stopped with 1/8 inch of lead

11. • Bremsstrahlung x-ray intensity increases with increasing
atomic number of absorber, and the average x-ray energy
increases with increasing electron energy.
(activity of the source is also a factor)
x-ray
e-

12. Interactions with Matter
* Photoelectric Effect
* Compton Effect
* Pair Production

13. Photoelectric Effect
• All photon energy is given up
• Part of the energy is used in
removing the electron from the
atom
• The rest of the energy is carried
off as the kinetic energy of the
electron
• Important when the energy of the
photon is low (less than 200 keV)
• More likely to occur in materials
with a high atomic number Z
• Lead has a Z of 82 and copper
has a 29

14. Compton Effect
• an increase in wavelength of X-
rays or gamma rays that occurs
when they are scattered.
• The change in wavelength of the
scattered radiation does not
depend upon the energy of the
incident photon.
• The Compton Effect is important
for gamma-ray energies between
200 keV and 5 MeV in most light
elements.
• The Compton Effect decreases
with increasing gamma energy
but not as quickly as the
photoelectric effect.
• Compton scattering is
predominant in substances of
intermediate Z.

15. Pair Production
• The process in which a photon of
sufficient energy gives up all its
energy and forms two particles,
an electron and positron, is
called a “pair production”
• Occurs near the nucleus of an
atom
• Energy is beyond MeV
• Both positron and electron lose
kinetic energy through ionization
of atoms in the substance
• Positron eventually interacts with
an electron in the substance in a
process called annihilation.

16. The Three Processes
• Photoelectric and Compton Effect decrease
with an increase of gamma energy.
• Pair Production increases with gamma energy.
• In radiation safety, we are concerned with the
absorption of radiation by matter so that we can
protect people from these rays.
• The three processes produce electrons, which
then ionize the absorbing matter.

17. Half Value Layer

18. Common Units
• Radioactivity
• Exposure
• Absorbed Dose
• Dose Equivalent

19. Radioactivity
• Rate of Decay / Potential to Decay
• “Strength”
• Curie (Ci) - 1 gram of radium disintegrates
• 3.7 X 1010 disintegration/second (dps)
• Becquerel (Bq)
= 1 disintegration/second (dps)
• 1 mCi = 37 MBq

20. Exposure
• Radioactivity is measured in Roentgens
(R)
• Charge produced in air from ionization by
gamma and x-rays
– ONLY for photons in air
– Rather infrequently used unit
• A measure of what is emitted

21. Absorbed Dose
• Energy deposited by any form of ionizing
radiation in a unit mass of material
• Roentgen Absorbed Dose (rad)
• Gray (Gy)
• 1 Gy = 100 rad

22. Dose Equivalent
• Scale for equating relative hazards of various
types of ionization in terms of equivalent risk
• Damage in tissue measured in rem
– (Roentgen Equivalent Man)
• Q:risk of biological injury
• rem = Q * rad
• Sievert (Sv)
• 1 Sv = 100 rem

23. What do we really need to know about dose
and why?
• 1 R 1 rad = 1 rem
• For gammas & betas*
• 1 rad 1 rem
• For alphas, neutrons & protons
• 1 rem = 1 rad * Q
• Dosage and dosimetry are measured and
reported in rems.
• All the Federal and State regulations are
written in rems.
• The regulators must be placated with reports in
rems.

24. Whole Body Effects of Radiation
• Acute or Nonstochastic
– Occur when the radiation dose is large enough to
cause extensive biological damage to cells so that
large numbers of cells die off.
– Evident hours to a few months after exposure (Early).
• Late or Stochastic (Delayed)
– Exhibit themselves over years after acute exposure.
• Genetic
• Somatic
• Teratogenic

25. Biological Effects of Radiation
Radiation passing through living cells will ionize or excite
atoms and molecules in the cell structure. These changes
affect the forces which bind the atoms together into
molecules. If the molecule breaks up, some of the parts
will be charged. These fragments are called radicals and
ions and are not chemically stable. Further effects are
produced when the radicals and ions interact with other
cell material. In this way, damage is caused in a direct
and indirect manner. These changes are called mutations
and can then affect either the daughter call or future cells.

26. Most and Least Sensitive Cells to Radiation

27. Effects to the Unborn
Effects on the embryo depend upon the dose as
well as the age of the fetus. The younger the
fetus, the more it will be affected. The unborn
human is the most radiosensitive since its organs
are rapidly developing and very susceptible to
damage.

28. So how do we protect ourselves
and our patients from
unnecessary radiation
exposure??

29. ALARA
As Low As Reasonably
Achievable

30. Time
Less time = Less radiation exposure
Shorten exposure times whenever possible
However, increasing exposure in order to
decrease time is not the answer.
Sometimes more time is necessary to
obtain an optimal image.

31. Distance
• Effective & Easy
• Inverse Square Law
– Doubling distance from source, decreases dose by
factor of four
– Tripling it decreases dose nine-fold
• More Distance = Less Radiation Exposure

32. Shielding
• Materials “absorb” radiation
• Proper shielding = Less Radiation
Exposure

33. MEDcare Sheilding
It is the policy of MEDcare to shield all
patients whenever possible. This means that
we should shield for every exam as long as
the quality of the exam is not compromised
by the shielding. Lead shields of different
sizes and shapes are located in each clinic
for this purpose.

34. Other Indications of Radiation
Wall Signs

35. Performance Evaluations are performed
annually on both x-ray and CT machines to
ensure that they are functioning properly

36. We work with medical physicists to ensure that our CT protocols are in
accordance with ACR regulations and standards. They also work with us to
create pediatric protocols based on weight to keep the child dose as low as
reasonably achievable. These protocols are located in the “Pediatric” tab on
the CT monitor. We follow the standards put forth through both “Image
Wisely” and “Image Gently”

37. Personnel Monitoring Devices
At MEDcare, we use Mirion Technlogies Thermoluscent film badges.
The TLDs respond accurately to beta, gamma, X-ray and neutron
radiation. The response of each element is corrected by the application
of its own unique element correction factor. These TLDs allow for the
reporting of deep, lens of eye and shallow doses. They are changed out
and reported on every 3 months. They are worn at the collar level and
should be left at the center each day. These reports are available for all
radiation staff in the Radiology QA binder located in the radiology
department. Fetal badges are available once a radiation worker
declares themselves as pregnant to the Radiation Safety Officer. These
are worn at the waist level. See Policy for Pregnant Radiation Workers.

38. Annual Occupational Dose Limits
*Declared Pregnant Women

39. Pregnant Patients
It is the policy of MEDcare to perform a urine pregnancy test
for each female patient within child bearing age that will
receive an X-ray or CT exam. This test should be performed
and resulted prior to the study being performed. If a patient
is pregnant and the benefits of a radiation exam outweigh
the risks, the physician can instruct the technologist to
proceed with the exam. However, the patient should be
shielded over the abdominal and reproductive areas
whenever possible. The patient should also sign the
pregnancy waiver indicating that they are aware of the
potential risks and choose to proceed with the exam. This
should be scanned into their chart. See policy on Radiation
Protection of Pregnant and Nursing patients.

40. Pregnant Patients
Each patient has the right to decline a
pregnancy test. If a patient declines the test,
this should be documented in the EMR. You
should ask the patient (whether they have a
pregnancy test or not) if there is any chance
of pregnancy. The response of this question
and the patient’s last menstrual cycle should
be documented in the EMR as well. The
patient should be shielded appropriately for
the exam.

41. Nursing Mothers
Although there is no
indication that IV contrast is
harmful to a nursing child
through the mother’s breast
milk, it is the policy of
MEDcare to instruct the
mother to “pump and dump”
for 48 hours after an IV
contrast administration
before nursing their child
again. See radiology policy
for Nursing Mothers.

42. Patient Holding
Radiologic Technologists are prohibited from holding
patients during radiographic examinations. If a patient
requires holding, a family member or guardian of the
patient is the first choice to do so. This person, as
well as the patient, must be shielded. You must also
document in the EMR the person that held the
patient. If a family member is not available to help
hold, a MEDcare employee who does not work in
radiation can help hold the patient. This employee
holding should be documented in the EMR as well as
documentation of the shielding that took place. See
radiology policy on Patient Holding.

43. IV Contrast Administration
• Physician must be on site when a tech administers IV contrast.
• Patient must be asked about any allergies to contrast in the past.
• Creatinine level must be obtained for all patients over the age of 50,
all diabetics and any patient with known renal disease prior to
administration of IV Contrast.
• Creatinine levels of 1.4 or above must be discussed with the ordering
physician before moving forward with the Contrast Administration.
• All Diabetics should be instructed to refrain from their oral
medications for 48 hours after an IV contrast administration. (Only
Oral Meds, Not Insulin Injections)
• If a patient on dialysis receives IV contrast, they should be instructed
to receive their dialysis treatment within 48 hours after administration
of IV contrast.

44. Pediatric Patients
• For anyone 16 and under, C-Spine and L-Spine
radiographic exams should be 3 views instead of 5
views.
• Lead shielding will be utilized whenever possible.
• Decreased dose by decreasing technical factors on
both CT and Radiologic Exams.
• CT Protocols based on weight of the child to ensure
smallest dose administered. (See pediatric tab on
CT machine)
• Limit multi-phase contrasted CT scans.
• Radiographic imaging of long bones can be
obtained.

45. Other Facts to Consider
We are exposed to radiation each day in the form of background radiation. This
can come from our environment, within our body, foods we eat and products we
buy.

46. Just Remember…
Medical imaging has revolutionized healthcare
over the past 30 years. It helps detect and
diagnose disease at its earliest stages when most
treatable. Imaging reduces the need for invasive
procedures by catching these diseases early,
therefore saving the patient money. Due to
radiologic advancements, “exploratory surgery” is
almost obsolete. Medical imaging is an
extraordinary tool and when used appropriately
and safely, has endless benefits.

47. Just Remember…
• Radiation is not something to be feared, but should be
respected.
• We are exposed on a daily basis to all types of radiation.
Those exposures serve no purpose. Medical imaging has a
great purpose in the world of medicine.
• If someone is apprehensive about an exam, you should be
comfortable explaining the risks but also the benefits of the
exam.
• At MEDcare, our exams are very low risk with high diagnostic
benefits. As long as the proper history is obtained and the
proper pre-exam testing performed, all patients are safe.
• This is why it is so important to know and understand the
radiology polices in place.

48. Policies and Procedures
Please be sure to read your radiology policies and
procedures. These are found in the X-Ray QA
binders located in each radiology department as well
as the clinic Policy and Procedure binder under the
“Radiology” tab. These polices are also located at the
end of this training module for you to print if you wish.
If you have any questions or concerns in regards to
radiation safety or policies and procedures, please
contact your Radiation Safety Officer, Crystal Wise
843-708-1606