Radiation Protection in nuclear medicine, dose managment durind operating procedure and patient safety...

1. Radiation Protection
in
Nuclear Medicine
Urmia University of medical science
Medical physics Department
Presented by M.Shafiee, MSc of Medical Physics
Shafieemp@yahoo.comShafieemp@yahoo.com

3. Aims and Objectives of Radiation
Protection
A L A R A
The objectives of radiation protection can be achieved by
reducing all exposure to as low as reasonably achievable
(ALARA) and by applying dose limits for controlling
occupational and general public exposures.
For radiation protection purposes, it is assumed that
the risk of stochastic effects is strictly proportional to
dose without threshold throughout the range of dose
and dose rates of importance in radiation protection.

4. Radiation Protection
Principles
Time
Minimize the amount off time during the exposure..
Distance
Maximize the distance from the radiation source..
Inverse-Square Law states that as you DOUBLE the distance
from a radiation source,, you reduce the exposure levels by
ONE-FOURTH ( 1/4 )..
Shielding
Utilize shielding to avoid direct exposure to the radiation source..

7. Hot Laboratory
• The center of receivement,store, transportation
and exit of radioactive materials in nuclear
medicine depatment.

8. Radiation Protection in
PET/CT
8
Mo-99 Tc-99m Tc-99
66 h 6h
NaCl
AlO2
Mo-99
+Tc-99m
Tc-99m
Technetium generator

9. 99
Mo-99m
Tc GENERATOR
99
Mo
87.6% 99m
Tc
γ 140 keV
T½ = 6.02 h
99
Tc
ß-
292 keV
T½ = 2*105
y
99
Ru stable
12.4%
ß-
442 keV
γ 739 keV
T½ = 2.75 d

11. 11
Categorization of hazard
Based on calculation of a weighted activity using
weighting factors according to radionuclide used and
the type of operation performed.
Weighted activity Category
< 50 MBq Low hazard
50-50000 MBq Medium hazard
>50000 MBq High hazard

12. CLASSIFIED AREAS
Should be defined by the RPO and RPC
Controlled areas:
•Room for preparation of radiopharmaceuticals
•Room for dispensing radiopharmaceuticals
•Room for storage of radionuclides
•Room for storage of radioactive waste
•Room for administration of radiopharmaceuticals
•Imaging rooms, if or when administration is done
Supervised areas:
•The whole department

13. “I.23. Registrants and licensees shall:
(a) delineate controlled areas by physical means or, where this is
not reasonably practicable, by some other suitable means;
(c) display a warning symbol
(d) establish occupational protection and safety measures,
including local rules and procedures that are appropriate for
controlled areas;
(e) restrict access to controlled areas
CONTROLLED AREA

14. (f) provide, as appropriate, at entrances to controlled
areas:
(i) protective clothing and equipment;
(ii) monitoring equipment; and
(iii) suitable storage for personal clothing;
(i) equipment for monitoring for contamination of
skin and clothing;
(ii) equipment for monitoring for contamination of any
object or substance
(iii) washing or showering facilities
(iv)suitable storage
CONTROLLED AREA

15. Shielding
Bench top shield
Vial shields
Syringe shields

16. SHIELDING OF SOURCES
Factors affecting the design:
•radionuclide
•activity
•shielding material
Dose rate constant
The dose rate (μSv/h) at 1 m
from a point source of 1 MBq

17. Syringe shield
400 MBq Tc-99m in 1 ml
No shield
0.4 mSv/h
0.8 mSv/h
4.2 mSv/h
22 mSv/h
8 mSv/h
Shielded (2mm pb)
0.004 mSv/h
0.01 mSv/h
0.04 mSv/h
0.16 mSv/h
6 mSv/h

18. Part 5. Occupational
Protection
18
Vial Shield
560 mGy/h
1 mGy/h
Tc-99m
10 GBq
10 ml
2 mm lead

19. Estimate the thickness of a lead container for 30 GBq
of Tc-99m. Dose rate at 1 m should be 2 μSv/h
Dose rate constant: 0.017 μSv/h&MBq
TVL: 0.9 mm lead
Dose rate for unshielded source: 0.017*30000=
510 μSv/h
Reduce exposure 255 times which equals 2.4 TVL=
2.2 mm lead.
Lead shield

20. Estimate the thickness of a lead container for 15 GBq of I-131.
Dose rate at 0.1 m should be 200 μSv/h
Dose rate constant: 0.058 μSv/h & MBq
TVL: 11 mm lead
Dose rate for unshielded source: 0.058*15000=
870 μSv/h at 1 m
Dose rate for unshielded source at 0.1 m= 87 mSv/h
Reduce dose rate 435 times which equals 2.64 TVL=
30 mm lead.
Lead shield

21. QC(quality control) in nuclear medicine
center:
• AntisepticAntiseptic technique for work with this
agents
• Air QualityAir Quality should be controled. Check up
for air pressure,air flow direction,air
violocity and efficentcy of filterring
• Good ventilationGood ventilation (hoods-laminar air flow
cabinets)

22. Display a warning symbol...

23. Equipment:
For radionucleid generators and kits the
following equipment is necessary:
• Activitymeter
• Choromatographic equipment
• Microscop for controlling fallout
• Antiseptic testing equipments

24. • Shower and lavatory for cleaning contamination
• There should be one radiation detector for
survey floor and surface of workbench
• When you working with radioactive substances
you should have disposal glove or lattix disposal
gloves.
• For pick up and transportation radioactive vials
should employ tongs with prolong handles, to
made greater distance and reducing absorbed
dose

25. Staff that work in nuclear medicine besides
other part in hospital,at entering and
exiting from nuclear medicine department
should exchange their covers, because of
prevention of carring contamination to
other area in hospitals!
Personal dosimeter sholdn’t use out of
nuclear medicine department!

26. Laboratory Rules for the Use of Radioactive
Materials
• Wear laboratory coats, or other protective clothing at all times in areas
where radioactive materials are used..
• Wear disposable gloves at all times while handling radioactive
materials..
• Monitor hands and clothing for contamination after each procedure or
before leaviing the area..
• Use syringe shields for preparation of patient doses and
administration to patients except in circumstances,, such as pediatric
cases, where theiir use would compromise the patient's well-being..
• Do not eat,drinking,smoke or apply cosmetics in any area where
radioactive material is stored or used..
• Assay each patientt dose in the dose calibrator prior to
administration..

27. Laboratory Rules for Use of Radioactive Materials-cont
• Do not use any doses that differ from the prescribed dose by
more than 10%..
• Wear personnel monitoring devices (Film badge or TLD) at all
times while in areas where radioactive materials are used or
stored. These should be worn at chest or waist level.
• Wear finger badges during elution of generator and
preparation, assay and injection of radiopharmaceuticals.
• Dispose of radioactive waste onlly in specially designated
recepttaclles.

28. • Never pipette by mouth..
• Survey generator, kit preparation and injection areas for
• contamination after each procedure or at the end of the day.
Decontaminate if necessary.
• Confine radioactive solutions in covered containers plainly
identified and labeled with name of compound, radionuclide,
date, activity and radiation level if applicable.
• Always transport radioactive material in shielded containers.
Laboratory Rules for Use of Radioactive Materials-cont

29. Radiological Units:
Quantity Unit Value SI Unit
Radiation
Exposure
R 2.58X 10-4
C/Kg
Absorbed
Dose
Rad 1X 10-2
Gy
Dose
Equivalent
Rem 1X 10-2
Sv
Radioactivity curie 3.7X1010
becquerel

30. Sealed sources for calibration of activity meters
RadionuclideRadionuclide Photon energyPhoton energy
(keV)(keV)
Half-lifeHalf-life ActivityActivity
(MBq)(MBq)
Co-57Co-57 122122 271 d271 d 185185
Ba-133Ba-133 81, 35681, 356 10.7 y10.7 y 9.39.3
Cs-137Cs-137 662662 30 y30 y 7.47.4
Co-60Co-60 1173, 13321173, 1332 5.27 y5.27 y 1.91.9

31. Summary of dose limits established in the Basic Safety Standards.
DOSE LIMIT (1)
APPLICATION Occupational
Effective dose 20 mSv per year averaged over defined periods of 5 years (2)
Effective dose to
the embryo or
foetus
1 mSv
Annual equivalent
dose in
the lens of the eye
the skin (4)
the hands and feet
150 mSv
500 mSv
500 mSv
1.
2.
3.
4.
The limits apply to the sum of the relevant doses from external exposure in the specified period and
the 50-year committed dose (to age 70 years for children) from intakes of radioactive nuclides in the
same period
With the further provision that the effective dose should not exceed 50 mSv in any single year.
In special circumstances a higher value of effective dose could be allowed in a single year, provided
that the average over 5 years does not exceed 1 mSv per year.
The limitation on the effective dose provides sufficient protection for the skin against stochastic
effects. An additional limit is needed for localised exposures to prevent deterministic effects.

32. Dose monitoring tools
Ion chambers Semiconductors TLDs Film
Advantages Well understood,
accurate, variety of
forms available
Small, robust Small, no cables
required
Two dimensional,
ease of use
Disadvantages Large, high voltage
required
Temperature
dependence
Delayed readout,
complex handling
Not tissue
equivalent, not
very reproducible
Common use Reference
dosimetry, beam
scanning
Beam scanning, in
vivo dosimetry
Dose verification,
in vivo dosimetry
QA, assessment of
dose distributions
Comment Most common and
important
dosimetric
technique
New developments
(MOSFETs) may
increase utility
Also used for
dosimetric
intercomparisons
(audits)
New developments
(radiochromic
film) may increase
utility

33. 0
0,5
1
1,5
2
2,5
Dispensing Injection Examination
Dose(uSv)
Bone scan
400 MBq, Tc-99m
Dose to worker

34. Part 5. Occupational
Protection
34
The activity on the hands after elution, preparation
and administration of Tc99m-radiopharmaceuticals
has been measured to 0.02-200 kBq, which results
in a skin dose of 0.005 to 50 mSv/h
Radionuclide Dose rate
mSv*cm2/MBq*h
Co-57 78
Ga-67 324
Tc-99m 243
In-111 376
I-123 365
I-125 417
I-131 1694
Tl-201 343
Contamination

35. Comparsion typical Effective Radiation Dose
from Diagnostic X Ray—Single Exposure
• Radiological x-ray procedures

38. Occupational Exposure
 Pregnant staff
• For external irradiation from Tc-99m or I-131, a dose
of 1.3 mSv to the surface of the maternal abdomen
has been shown to give rise to a dose of 1 mSv to
the fetus.
• For higher energy photons, such as those from
positron emitters, the dose to the fetus may be
similar to the dose at the surface of the abdomen.

39. Approximate fetal whole body dose (mGy) from common
nuclear medicine procedures done in early and late pregnancy
Procedure Activity
(MBq)
Early 9
months
Tc-99m
Bone scan
Lung V/Q scan
Liver colloid
Thyroid scan
Renal DTPA
Red Cell
750
240
300
400
750
930
4.7
0.9
0.6
4.4
9.0
6.0
1.8
0.9
1.1
3.7
3.5
2.5
I-123 Thyroid
uptake
30 0.6 0.3
I-131 Thyroid
uptake
0.55 0.04 0.15

41. Occupational Exposure
 Lead Aprons
In certain circumstances staff may need to wear a protective lead
apron. This may be necessary if staff need to be in close
contact with patients containing greater than 800 MBq of Tc-
99m, such as during myocardial perfusion studies or gated
cardiac blood pool studies. Protective aprons should
preferably have a thickness of 0.5 mm lead equivalence.
Lead aprons provide little or no protection for higher
energy photons and should not be used for Radionuclides
such as Ga-67 or I-131 or for positron emitters.

42. 0
20
40
60
80
100
120
0 1 2 3 4 5 6
Decontamination
Remaining activity (%)
Number of washings
Tc99m pertechnetate

43. MONITORING OF THYROID
(internal contamination)

44. Skin EffectsSkin Effects
By handling unshielded syringes and vials containing
radioactive material the threshold dose of skin erythema
will be reached in a short time.
Example: The dose rate at the surface of a vial
containing 30 GBq Tc99m is of the order of 2 Gy/h
meaning that the threshold dose will be reached after
2 h of exposure. This corresponds to 36 s per working
day in a year

45. For patient with I-31 therapy and
radioactive dosage above 20mci I-
131, they should hospitalize in
special rooms, and be controlled
and folow up for their requirment
and when their radiation decay at
1m distance of patients skin stike
a balance, they could be
discharge.

46. Patient with iodine-131
1000 MBq
I-131
0 0.5 1 2 m
0.5 0.1 0.06 0.03 mSv/h
I-131 8.04 d β-
Particle E:
0.33 (9%)
0.61 (87%)
more
Photon E:
0.365 (80%)
0.640 (9%)
more

47. Tired..?

48. THYROID MONITORING LOGBOOK
All Nuclear Medicine personnel involved in use of I-131
sodium iodide in quantities >1 mCi must have a
routine thyroid count performed every 6 months; in
addition, 24 hours after an iodination procedure or
administration of I-131 sodium iodide in liquid form,
the thyroid must be counted.

49. Examples of Waste from Nuclear Medicine
•Biological waste which may undergo decomposition.
•Infectious waste requiring sterilization prior to disposal.
•Broken glass-ware, syringes etc, requiring collection in
separate containers to prevent personnel being injured.
•Radionuclide generators
•Bed linen and clothing from hospital wards.
•Liquid scintillation solutions
•Patient excreta

50. 50
Segregation/Waste Containers
Containers to allow segregation of different
types of radioactive waste should be
available in areas where the waste is
generated. The containers must be suitable
for purpose (volume, shielding, leak proof,
etc.)
•Glassware with radionuclides (short half-life)
•Syringes and needles
•Gloves and paper
•Glassware with radionuclides (medium half-
life)

51. 51
A room for interim storage of radioactive waste should be
available. The room should be locked, properly marked and
ventilated.
Each type of waste should be kept in separate containers
properly labeled to supply information about the
radionuclide, activity concentration etc. Flammable goods
should be kept apart.
Records should be kept where the origin of the waste can
identified.
Storage of Radioactive Waste

52. Part 10. Radioactive
waste
52
Storage of Radioactive Waste

53. Part 10. Radioactive
waste
53
•Storage of Radioactive Waste

54. Part 1. Biological effects
of ionizing radiation
54
Health consequences
of Chernobyl accident
•1800 children diagnosed with
thyroid cancer (1998)

55. • Solid waste.
Cover papers, gloves, empty vials and syringes.
Radionuclide generators. Items used by hospitalized
patients
after radionuclide therapy. Sealed sources used for
calibration of instruments. Animal carcasses and other
biological waste.
• Liquid waste.
Residues of radionuclides. Patient excreta. Liquid scintil-
lation solutions.
• Gaseous waste.
Exhausted gas from patients in nuclear medicine
Radioactive Waste in Nuclear Medicine

56. Part 10. Radioactive
waste
56
Example of national regulations of disposal of waste from
hospitals:
Disposal via the public waste treatment system
•The dose rate at the surface of each package should be
<5 uGy/h.
•The package should not contain any single sealed source
with activity >50 kBq.
•Each package should be properly labeled with a warning
sign containing information on radionuclide and activity. The
origin of the waste should also be given on the package.
Disposal of Solid Waste

57. 57
Quality Assurance
•Local rules
Normal working conditions
Accidents
•Waste identification and traceability
Record system
•Process control
Safe handling of radioactive sources
Facilities
Monitoring
Quality of containers
Arrangements for storage
Documentation
•Audits

58. GoodGood
LuckLuck