medical radiation safety awareness

1. Medical Radiation Safety Awareness
Soe Hlaing . Dip.Civil.Eng: B,S.BSC,MPA.
Healthcare Engineer
Associate of American Healthcare Engineering
Certified MRSO, DOT ( USA )
8th March :2017 , UOPH.

2. We live in Sea of Radiation
COSMIC
p+ , ē , α2+
TERRESTRIAL ( Th 90,U , Ra, K 40 )
AIR
Inhaled
Radon,Thoron
FOOD and WATER
INTERNAL
α2+ β Γ
rays

3. Sources of Radiation
(620 mrem /year)
Natural(50%)
• Cosmic
• Terrestrial
• Radon
• Internal
(food and water)
Man-Made(50%)
• Medical
• Industrial
• Occupational
• Consumer products
360 mrem/yr NCRP Report 1994
620 mrem/yr NCRP Report 2009

4. Man-Made Radiation
Consumer Products 2%
Fiesta ware , uranium glass
Industrials < 0.1 %
Occupational < 0.1 %
Medical 48%

5. Radon Gas

6. Orders of magnitude (radiation)
Source:
http://en.wikipedia.or
g/wiki/Orders_of_ma
gnitude_(radiation)
Updated: 2017-02-
02T12:26Z

7. Radiation Risk Perceptions
• Why are we interested in radiation risk?
• Perceptions drive our beliefs, decisions and
reactions to radiation.
• Fear of Radiation is Common
• Understanding these fear is helpful for
understanding response to radiation
• Without understanding fears take over
- we are most afraid of what we know the least about?

8. Two Types of Radiation Views
Common Views
• Mysterious
• ( cannot detect by our
five senses)
• Sinister
( Unknown Danger)
• Deadly
( Causes Cancer )
Scientists’ views
• Parts of Natural World
easily measurable
• Risks are well known
since 1896
90 min- 21milli sec
• Major Benefit in
Medicine
treatment for Cancer

9. The LINEAR NO-THRESHOLD MODEL
(LNT)
• The model used in radiation protection to
estimate the long-term, biological damage
caused by ionizing radiation
• It assumed that the damage is directly
proportional (“linear”) to the dose of
radiation, at all dose levels
• Radiation is always considered harmful
with no safety threshold

10. Threshold and Hormesis Model
• Threshold: very small exposures are
harmless
• Radiation Hormesis Model: radiation at
very small doses can be beneficial
• Not enough data clearly in favor of any
theory. No definitive answer. However, LNT
model is used worldwide for radiation
protection regulations

11. Competing Theories on Hazard

12. Radiation Protection Purposes
• it is assumed that any dose above zero can increase the
risk of radiation-induced cancer (i.e., that there is no
threshold)
• Epidemiologic studies have found that the estimated
lifetime risk of dying from cancer is greater by about
0.004% per mSv (0.04% per rem) of radiation dose to the
whole body (NRC, 1990)
• Ref: An Evaluation of Radiation Exposure Guidance for Military
Operations: Interim Report (1997). J. Christopher Johnson and Susan
Thaul, Editors. National Academy of Sciences. ISBN 0-309-05895-3.

13. What are the effects of radiation?
• Large doses of radiation from some
procedures may cause temporary skin burns.
However, a greater concern is that radiation
may cause cancer. There is no conclusive
evidence that radiation causes cancer, but
large population studies have shown a slight
increase in cancer even from small amounts of
radiation.
• Ref: RadiologyInfo.org

14. External Radiation Protection
• Time , Distance , Shielding
• Neutron absorbed by low density materials
• Beta stopped by plastic or wood
• Photons shielded by lead or other
dense materials
• Bremasstrahlung with Beta emitters?

15. Internal Radiation Protection
• Routes of Entry
• Prevention of Intakes
• Detecting and Quantifying Intakes
• Medical Intervention
• Regulatory Limits  ALIs and DACs
• Notification Requirements
(in or external irradiation)
• Abbr: ALIs- Annual limit Intake
• DACs- Derived Air Concentrations

16. Radiation Doses
• Different from medicine dose. Intensity and length of exposure
• Different types of units and Measurement.
• Absorbed dose is used to assess the potential for biochemical
changes in specific tissues. Tell us energy deposit in a small volume
of tissue. Unit- milligray (mGy)
• Equivalent dose is used to assess how much biological damage is
expected from the absorbed dose. (Different types of radiation
have different damaging properties.) Addresses the impact that the
type of radiation has on that tissue.
Unit- milliSievert (mSv)
• Effective dose is used to assess the potential for long-term effects
that might occur in the future

17. • Effective dose is a calculated value, measured in
mSv, that takes three factors into account:
1 .the absorbed dose to all organs of the body,
2.the relative harm level of the radiation, and
3.the sensitivities of each organ to radiation.
eg: the head is less sensitive than < the chest.
• Effective dose relates to the overall long-term risk to
a person from a procedure and is useful for
comparing risks from different procedures.
Effective Dose

18. Effective Dose
• Effective dose is not intended to apply to a
specific patient.
• The actual risk depending on the size of the
patient and the type of procedure.
• Example of CT of the abdomen,
• Typical absorbed dose: 20 mGy
• Typical equivalent dose: 20 mSv
• Typical effective dose: 15 mSv

19. Effective Radiation Dose

20. Effective Radiation Dose

21. Effective Radiation Dose

22. Dose Limits for Occupational
Exposure of any Workers
• Following limits be not exceeded,
a. An effective dose of 20 mSv/yr averaged over 5 consecutive
yrs:
b. An effective dose of 50 mSv in any single year ( 16-18 6mSv)
c. An equivalent dose to lens of eyes of 150 mSv in a yr (50 )
d. An equivalent dose to the extremities (hand and feet) or
skin of 500 mSv in a year ( for16-18 aged 150 mSv)
Ref: IAEA SAFETY GUIDE No-G-1.1
page19 .para.3.1

23. Recommended Doses
• The value of 50 mSv in a year that you quote is a
number recommended by the
Health Physics Society (HPS) in
* position paper in 2010*
Radiation doses that exceed a minimum (threshold)
level can cause undesirable effects such as
depression of the blood cell-forming process
(threshold dose = 500 mSv, 50 rem) or cataracts
(threshold dose = 5,000 mSv, 500 rem)*

24. IAEA .BSS Intervention Situation
• Type 1. Emergency Exposure Situation
* Accident and other temporary exposure
• Type 2. Chronic Exposure Situation
* Natural Exposure – such as radon to
work place and building
* Radioactive Residues from past events
radioactive contamination
Ref: BSS (Ref. 2. para.3.1)

25. Radiation Safety Standards

26. ALARA and Inverse Square Law
• ALARA
• As Low As Reasonable
Achievable
• inverse-square
law
• specified physical quantity
or intensity is inversely
proportional to the square
of the distance from the
source of that physical
quantity.

27. Nature of Rays and Shielding

29. X Ray and Fluoroscopy Safety
• Sources of exposure
1. Primary Beam
- very intense exposure in beam
- Small beam diameter
2. Scattered radiation
- low intensity
- large area of exposure
- from housing leakage
- from any target material

30. Types of Radiation

31. Sources of Exposure
• X-Rays leakage
• Sky shine- Scattered
• Inadequate shielding
• Not following safety procedures
-by passing interlocks etc:
• Not using or heeding radiation instruments
• Not using PPE, lead apron , etc:

32. Principles of Radiation Protection
• Minimize Time around x-ray machines when in
operation
• Minimize Distance between you and the x-ray
source
• Utilize Shielding whenever possible
-lead aprons, lead-lined gloves, collar / thyroid
shields, shield booths

33. Sources of Exposure of Staff in PET
• *Radiation Sources
- Syringes containing PET doses
- Calibration and transmission sources
- Patients and their specimens
• *Staff exposures
- Staff not in room during CT potion
- PET technologist is twice that of non-PET tech in
Nuclear medicine dept:
“Carey-Clinical PET, AAPM meeting July 2001”

34. ALARA in PET-CT
Time - Minimize Time
consider- rotation for staff in PET
Distance- Maximize Distance
Use IV access for injections- also reduce injection time
Use remote handling devices when possible
Spend less time at patient side, take step back when
possible
Shielding- Use Shielding
Tungsten syringe shield ( 9mm reduces FDG exposure 88%)
L-Block / mobile Shielding

36. ALARA –Operator Positioning of
C-arms
• Scatter radiation intensity is less on
image intensifier side as compared to
the x-ray tube side
• Lateral and oblique projection
position the x-ray tube
on the opposite side of
the patient from
you where you are standing

37. Radiation in Therapy
• Treatment of a medical condition by:
• 1. Killing Cells ( DNA Bond breaking or disrupting
tumor blood flow) OR
• 2.Slowing the Growth of Diseased Cells using
radiation
• It uses high-energy particles or waves, such as x-
rays, gamma rays, electron beams, or protons, to
destroy or damage cancer cells. Other names for
radiation therapy are radiotherapy, irradiation, or
x-ray therapy.

38. Types of Sealed Sources
• Calibration Sources
• Germanium transmission Sources
• Flood Sources and Flexible rulers
• Manual Brach therapy Sources
• Teletherapy Sources ( Gamma Knife,
View Ray and Gammapod)
• Irradiators
Co 60 half life 5.26 yr
Cs 137 half life 30.17 yr
• After loaders

39. • Contact Dose Rates on Sealed Sources may
be Very High, Especially Cs – 137
• NEVER TOUCH A SEALED SOURCE CAPSULE
Radiation Burns may manifest themselves
month after exposure
WARNING

40. Radioactive Waste Management
• Define radioactive waste
• Review pertinent regulation
• Understand decay-in-storage
• Know the required elements of a radioactive
waste management program

41. Radioactive Waste Management
• Define radioactive waste
• Review pertinent regulation
• Understand decay-in-storage
• Know the required elements of a radioactive
waste management program

42. Radioactive Waste Segregation
• Physical form
• Half-life
• Other hazards
- chemicals
- Bio hazardous materials
• Combustible from
- non- combustible
Siriraj Hospital Cancer Center ,
2016

43. Waste Packaging and Storage
• Description of storage Area
• Location and diagrams
• Equipment, monitoring stations, effluent,
• Type of building , Protection from elements
• Security, Ventilation,
• Fire protection systems
• Temperature and humidity effects on waste container
• Packaging/container to be used
• Inspection program
• Remote handling program
• Radiation protection program elements
• Shielding needs if any ,

44. Radioactive Waste Minimization
• Training of workers
• Segregation of wastes
• Use less radioactive materials
• Use Short-Lived radionuclide's -up to 100 days
• Segregate chemical and radioactive materials
• Use non-radioactive methods
• Treat waste on-site
• Check for contamination

45. List of half-lives
• yttrium Y-90, used for radioembolization treating lymphoma
(2.7 days)
• I-131, used for thyroid function tests and for treating thyroid
cancer (8.0 days)
• Strontium Sr-89, used for treating bone cancer, intravenous
injection (52 days)
• Iridium Ir-192, used for brachytherapy (74 days)
• Co-60, used for brachytherapy and external radiotherapy (5.3
years)
• Cesium Cs-137, used for brachytherapy, external
radiotherapy (30 years)

46. PPE and Signage for Radiation

47. • Ref:
• Sandy E.Konerth, MS,DABR,DABMP
• Alan Fellman,PH.D.,CHP
• Lee Myers,PH.D.
• www.radiologyinfo.org
• Radioactive Materials Regulatory Guide
Minnesota Department of Health
• Global Threat Reduction Program .
Training Course on Physical Protection and Security
Management of Radioactive Sources
• Radialogyinfo.org
• IAEA SAFETY STANDARDS SERIES
SAFETY GUIDE NO.RS-G-1.1