2. What is Radiation?
Radiation: energy in motion
Radioactivity: spontaneous emission of radiation from the
nucleus of an unstable atom
Isotope: atoms with the same number of protons, but different
number of neutrons
Radioisotope: unstable isotope of an element that decays or
disintegrates spontaneously, emitting radiation. Approximately
5,000 natural and artificial radioisotopes have been identified
4. Ionizing radiation
Occurs from the addition or removal of
electrons from neutral atoms
Four main types of ionizing radiation
alpha, beta, gamma and neutrons
Alpha
Beta
Gamma (X-ray)
n Neutron
5. Types of Radiation
Non-Ionizing Radiation: Radiation that does not have sufficient
energy to dislodge orbital electrons.
Examples of non-ionizing radiation: microwaves, ultraviolet
light, lasers, radio waves, infrared light, and radar.
Ionizing Radiation: Radiation that has sufficient energy to
dislodge orbital electrons.
Examples of ionizing radiation: alpha particles, beta particles,
neutrons, gamma rays, and x-rays.
9. 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
10. 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 = rad
Sievert (Sv)
1 Sv = 100 rem
11. Dose Definitions
DAP -dose area product (Gycm²) incident dose x
area of X ray field
Entrance skin dose –absorbed dose in the skin at a
given location on the patient (Gy)
14. Whole Body Effects
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
15. Most and Least Radiosensitive Cells
Low Sensitivity Mature red blood cells
Muscle cells
Ganglion cells
Mature connective tissues
High Sensitivity Gastric mucosa
Mucous membranes
Esophageal epithelium
Urinary bladder epithelium
Very High Sensitivity Primitive blood cells
Intestinal epithelium
Spermatogonia
Ovarian follicular cells
Lymphocytes
16. Biologic Effects of Radiation
Deterministic injuries
When large numbers of cells are damaged and die immediately or
shortly after irradiation. Units of Gy.
There is a defined threshold dose for visible post procedure injury
from erythema to skin necrosis.
Stochastic injuries
Post radiation damage, cell descendants are clinically important.
Higher dose, the more likely the process, and therefore based upon
probability statistics.
There is a linear non-threshold dose identifiable for radiation-
induced neoplasm and heritable genetic defects. This is defined in
units of Sv.
17. Radiation Risks to the
Operator
Orthopedic injury: Interventionalists have high rates of orthopedic
injury. Approximately 50 % of respondents reported at least one
orthopedic problem.
Brain tumors: Interventionalists are typically positioned with the left side
of their body close to the patient’s chest and X-ray source,
86 % have been located on the left side of the brain. The
average radiation exposure left side of the head is 4.7 times
the dose of the right.
Vascular aging: New research provides evidence that continued
exposure to low-dose ionizing radiation also increases cardiovascular (CV)
risk. Carotid intima-media thickness (CIMT) and leukocyte telomere length
(LTL) are markers for atherosclerosis and biological aging, respectively.
Cataracts: 50% of interventional cardiologists have lens changes that
are a precursor to cataracts commonly associated with radiation exposure.
Thyroid disease: includes malignant and benign thyroid tumors.
18. Comparison of Administrative, Regulatory and Biological
Effect Doses
100% of People Die,
CNS Syndrome
Permanent Infertility
Whole Body Regulatory Limit (5 rem/yr)
Eye Regulatory Limit (15 rem/yr)
50% of People Die (450 – 500 rad)
Nausea & Vomiting (10% of People)
Whole Body UTHSCH Administrative
Limit (0.125 rem/month)
Whole Body Exposure
Partial Body Exposure
Extremities Regulatory Limit (50 rem/yr)
Eye UTHSCH Administrative
Limit (0.375 rem/month)
Rad or Rem
Extremities UTHSCH Administrative
Limit (1.275 rem/month)
General Public Whole Body Regulatory
Limit (0.100 rem/yr)
No Clinical Symptoms Seen Below 10 rem
Cataract Formation
Loss of Hair
Skin Reddening
Decreased White Blood Cell Count
Ulcers on the Skin
Molecular Death (> 100,000 rad)
Gastrointestinal Syndrome
19.
20. Summary of Biological Effects of
Radiation
Radiation may…
Deposit Energy in Body
Cause DNA Damage
Create Ionizations in Body
Leading to Free Radicals
Which may lead to biological damage
21. Why Establish Occupational
Exposure Limits?
We want to eliminate ability of
non-stochastic effects (Acute) to
occur
Example: Skin Reddening
We want to reduce the
probability of the occurrence of
stochastic effects (Chronic)
to same level as other
occupations
Example: Leukemia
Established from
Accident Data
22. X-rays Traverse the
Patient
X-ray Tube
Generator
A few x-rays get
through. Most are
absorbed, attenuated
or scattered. Skin
exposure greatest.
Much occupational
scatter below table.
Image Intensifier
The x-ray
beam
diverges as
it leaves the
x-ray tube.
Patient
23. Radiation protection equipment
in a modern cardiac
catheterization laboratory. In this
picture you will find ceiling-
mounted lead glass shield, under-
table lead curtain, radioabsorbent
patient drape, real-time
radiation dose monitor, Zero-
gravity system, and a rolling lead
shield.
25. Under development
Digital Amplification of Images
Less images/sec in each cine run
Robotics
Lead mounted on floor, suspended from ceilings
Shielding mounted on and around the image
intensifier
26. Dose Definitions •Gray -energy
absorbed per unit mass (in diagnostic
= KERMA, energy transferred)
Effective dose –equivalent dose in
each organ and tissue x tissue
weighting factor and summed over
whole body
27. How do we minimize occupational risk?
The (modified) As Low As Reasonably Achievable
principle
28. ALARA
As Low As Reasonably Achievable
How?
Time
Distance
Shielding
Why?
Minimize Dose
29. Time
Less time = Less radiation exposure
Use RAM only when necessary
Dry runs (without radioactive material)
Identify portions of the experiment that can be altered in order to
decrease exposure times
Shorten time when near RAM
Obtaining higher doses in order to get an
experiment done quicker is NOT “reasonable”!
30. 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
Tongs, Tweezers, Pipettes, Pliers
33. •
Shielding used where
appropriate
Significantly reduces
radiation effects
Lead
Plexiglas
Radiation Shielding
34. Radiation use will be labeled on door, work area & storage area
Research laboratories work with very low levels of radioactive materials
Safety can check for potential contamination prior to work in a lab that
uses radioactive materials
As a precaution: wear gloves, safety glasses and wash hands
Radiation Postings
35. Active processes
Education and training of the staff
Routine radiation dose monitoring
Personal dose meters
Real-time dose monitoring
Procedural techniques in reducing radiation
exposure
Limiting fluoroscopy time
Minimize use of high contrast modes
Use of lower frame rates whenever possible
Avoiding use of steep angulations
Utilize available radiation-reducing technology
36. Low pulse-rate fluoroscopy options
Low dose-per-frame
Low frame rate options
Spectral beam filtration
Higher X-ray beam energy
Use of image noise reduction technology
Distance from radiation source
Optimal table positioning-higher table setting if
possible
Staying at low scatter radiation areas for the staff
Keeping non-target anatomy away from the X-
ray beam
37. Passive processes
Architectural shielding
Rolling leaded transparent shields
Stationary leaded transparent shields
Equipment-mounted Ceiling-suspended shields
Table-suspended curtains and drapes
Radioabsorbent patient drapes
Radial arm boards
Personal protective equipment
Caps ,Eyewear ,Thyroid collar
Aprons
Lead acrylic face mask
39. Protective equipment Reduction in radiation
Radioabsorbent surgical caps 3.3%
Leaded glasses 35–90%
Gloves 20–50%
Thyroid collar >95%
Lead apron >95%
Radiation reduction with various
equipment
40.
41.
42.
43. Annual Radiation Exposure
Limits
Occupationally Exposed Worker:
rem mrem
Whole body 5 5000
Eye 15 15,000
Shallow 50 50,000
Minor 0.5 500
Pregnant Worker 0.5* 500*
_____________*9 months_
General Public: 100 mrem/year or 2mrem/hour
44. Whole Body
Total Effective Dose Equivalent (TEDE)
TEDE = Internal + External
Assume Internal Contribution Zero
Unless Ingestion, Absorption or Inhalation
Suspected
Limit = 5 rem / yr
45. Ensuring Compliance to Radiation
Exposure Limits
Use the established activity limit for each isotope
Compare with similar situations
Estimate with meter
Calculate
Time, Distance, Shielding, Type, Energy, Geometry
Measure
TLD Chip, Luxel
Bioassay
46. Who should wear radiation
dosimeters or badges?
Those “likely” to exceed 10% of their
annual limit are required
Those who would like a badge
Minors & Declared Pregnant Workers*
47. Rules, Rights & Responsibilities as
a Radiation Worker
Department of State Health Services
Radiation Control
Atomic enegy Regulation Board
48. Future directions
Given the harmful effects of radiation, several
technological advancements have been developed
that will help reduce radiation exposure to the
operator, patient, and staff in the cardiac
catheterization laboratory. Intravascular ultrasound
(IVUS) provides detailed coronary arterial wall
architecture and lesion morphology.
49. Robotic remote-control angioplasty where
interventional cardiologists work from a shielded
workstation away from the radiation source have
also been shown to reduce radiation dose by as
much as 96%
Real-time radiation dose monitoring has been
shown to alter operator behavior during the
procedure resulting in reduction in the peak skin
and total radiation dose of the patient .More
widespread use of this technology will be helpful
in decreasing radiation exposure.
