Details about Therapeutic Nuclear Medicine

1. Therapeutic
Nuclear Medicine
P SABARI KUMAR
M.Sc. Radiation Physics
KIDWAI CANCER INSTITUTE

2.  Introduction
 Isotopes used in Therapy
 Administration Procedures
 Internal Dosimetry
 Designing a Nuclear Medicine Dept.
 Radiation Protection
OUTLINE

3. Introduction
Radionuclides are being extensively used for treatment of
various benign and malignant conditions like hyperthyroidism,
thyroid carcinoma, painful bone metastases, arthritis etc.,
It is a rapidly expanding cancer treatment modality
Unsealed radioisotopes are directly administrated to the
patient in this treatment modality.
Radiation protection in radionuclide therapy requires control
of both external exposure and contamination of the medical
staff, laboratory personnel, family members, visitors and general
public

4. Biological Half life:
Biological Half life is defined as the exponential removal of radio
activity from the organs as well as from the whole body
This help us understand the dynamics of radio nuclide retention
times, internal dosimetry, and risks of radiation injury
Effective Half Life:
The time in which half of the radio activity is
removed from the organ or from the whole
body by the combined processes of radioactive
decay and biological excretion.
Element Whole Body Tb Organ Organ Tb
Iodine 138d Thyroid 138d
Calcium 4.5y Bone 4.9y
Cesium 70d Whole Body 70d
Sodium 11d Whole Body 11d
bp
bp
e
TT
TT
T




5. Annual Limit on Take: (ALI)
The amount of radioactive material allowed to be taken into the
body of an adult worker as a result of inhalation or ingestion in a
year
e – Effective dose co-efficient is a measure of damage done by
ionizing radiation associated with radioactivity of an isotope (units:
Sv/Bq).
It accounts WR & WT , metabolic & biokinetic information
Factors affecting the calculation of the ALI are:
Chemical form,
retention time in the body,
 for inhalation – the aerosol activity median
aerodynamic diameter
)50(e
Sv02.0
tcoefficien.dose.effective.committed
equivalent.dose.effective.committed
ALI 

6. Derived Air Concentrations:
It is calculated by dividing the limit on intake by the volume of
air breathed over the working period.
If a reference person inhales 20lt of air/min then,
DAC = ALI Inhale (Bq)/2400 x 103 lt/year
Ex: 137Cs has an ALI Inhale of 3 x 106 Bq/year
DAC = 3 x 106 Bq/year /2400 x 103 lt/year = 1.25 Bq/lt
Derived Water Concentration:
It is calculated by dividing the limit on take by the volume of
water intake over the working period.
If a reference person water intake is 2.5 lt/day then,
DWC = ALI ingest (Bq)/ 912.5lt/year

7. Committed Dose:
The total dose delivered during the period of time when radio
nuclide is administrated into the body is referred to as Committed
dose and is calculated as a specified time integral of the rate of
receipt of the dose
Where
t0 - time of intake
τ – Integration Time
For adults τ is taken as 50 years and for children it will be 70 years
Committed Effective Dose:
Committed effective dose is measure of radio-toxicity (the dose
received by a population ingesting all the radio active material
present at a given time)
Radio toxicity = E(τ) . A



0
0
t
t
TT dt).t(H)(H
 
T
TT )(H.W)(E

8. Isotopes used in Therapy – NM
Beta or Alpha emitting radio isotopes are used in mostly. But
presence of gamma is helpful in imaging & studying of bio-
distribution of radio nuclide
Physical & Biological half lives should be paired to the drug
half life in the body.
Simple, stable radio-labeling to biological compounds is one of
the most important quality for an ideal therapeutic isotope
Binding efficiency & stability of a radio labeled compound
results in optimal delivery of radiation in vivo
There should not be any significant radiolysis of the compound
after labeling, during storage and shipment

9. Isotopes used in Therapy – NM
Radioisotopes used in therapy are largely divided into two
types : Radio-metals and Radio-halogens
Radio-metals have long been attractive options and have gained
widespread popularity for many clinical uses
Radio-halogens have maintained their popularity because of
their relatively simpler radio-labelling characteristics.
Radionuclide
Beta Emax
(MeV)
Max Range
(mm)
Mean
Range (mm)
Gamma energy
(KeV)
Half life
(hr)
32P 1.71 8.7 1.985 - 342
131I 0.61 2.4 0.4 364 193
89Sr 1.46 8.0 - - 1212
211At+ 5.9 (Alpha) - 0.06 670 7.2
212Bi 1.36 (beta)
6.1 (alpha)
- 0.09
0.06
727 1.0

10. Isotopes used in Therapy – NM
131 I
Normal physiological uptake of iodide in functioning Thyroid
tissue is the primary reason for its role in treating several thyroid
disorders & malignancies.
Nuclear Fission (235U) product
Half life : 8.1 days
Beta Energy (max) : 600 KeV
Gamma Energy : 364 KeV
Administration in the form of liquid Sodium Iodide

11. Isotopes used in Therapy – NM
32 P
31P (n,γ)32P
The ratio of phosphorus uptake in tumorous bone relative to
normal bone is about 2:1
Reactor Produced and Pure beta emitter
Half Life : 14.3 days
 Energy (average) : 694.7KeV
Average range of beta rays in water :0.198cm
Used for Polycythemia Vera treatment
Administration in the form as Sodium Phosphate

12. Isotopes used in Therapy – NM
89Sr
Fission product and Pure beta emitter
Half Life : 50.5 days
 Energy (max) : 1.46MeV
It is handled by body in the same manner as calcium
Used for Bone Metastases

13. Administration Procedure
131 I Administration:
The most common form of Hyper-thyroidism is Grave’s disease
and 131 I is the treatment choice for this.
Also beneficial of metastatic thyroid cancer treatment
Treatment doses of 200-400 MBq (5 – 10 mCi) administrated to
reduce the incidence of Hypo-Thyroidism.
Patient should discontinue anti-thyroid medication prior to
therapy for 2 – 8 days
Female patients should be advised to not conceive for at least
six months following therapy
No intravenous contrast should be administrated for at least two
months prior to therapy

14. Administration Procedure
131 I Administration:
Patient should be encouraged to reduce iodine content in diet to
optimize uptake of 131I by thyroid tissue
Patient should be empty stomach at least 1 to 2 hrs before and
after therapy to reduce the volume of vomits
A tracer study may be carried out prior to administration of 131I,
to ensure 131I uptake in thyroid tissue and/or in metastatically
diseased tissue
131I is given orally; neck uptake and imaging is carried out
between 24 and 72 hrs after administration
Whole body imaging at 72hrs should also be carried out,
especially when results of neck imaging are negative

15. Administration Procedure
32P Administration:
Polycythemia Rubra Vera is a chronic hameotological disorder
characterized by increased proliferative activity of the erythroid,
myeloid and fibroblast cell lines.
Sodium 32P is used for treatment of PRV; supplied as
orthophospate
32P is administered by intravenous injection using canella; care
must be taken to avoid extravasations
The biological half life of the radio pharmaceutical in Bone
Marrow is 7 to 9 days

16. Administration Procedure
32P Administration:
Two treatment approaches are used:
Fixed Approach
Sliding Approach
In fixed one, 74 – 111 MBq (2 – 3 mCi)/m2 body surface area is
administrated with an upper limit of 185MBq (5mCi). This may
be repeated at three monthly intervals
In sliding scale, a fixed dose of 111MBq (3mCi) is first
administrated. If there is no response a second treatment may be
given after three months with a 25% increment in dose.
Treatment may be repeated with continuing dose increments until
an adequate response is obtained the upper limit for a single
treatment is 7mCi.

17. Internal Dosimetry
Absorbed Dose depends on :
 The amount of radioactivity administrated
 The physical and biological half lives of the radio nuclide
 The fraction of abundance of the radiation in question from
the radionuclide
 The bio distribution of radio activity in the body
 The fraction energy released from the source organ that is
absorbed in the target volume, which is related to the shape,
composition and location of the target

18. Internal Dosimetry
The energy absorbed per hour by the target, due to ith radiation is:
Total Dose becomes,
Where,
A0 = Initial Activity of Radio Nuclide
m = mass of target v = volume of target
f = fraction of activity localized in organ
i = Equilibrium Dose constant (g.rad/μCi.hr)
= 2.13Ni.Ei
Te = Effective Half Life of radio nuclide
Φi(v ← r) = Absorbed fraction
)rv(.T.).f.
m
A
(44.1)hr/rad(R iei
0
i 


n
1i
iie
0
)rv(..T).f.
m
A
(44.1D

19. Internal Dosimetry
Φi – Absorbed Fraction is defined as ratio of energy absorbed by
target to energy emitted by source
Φi depends on the type & energy of radiation, shape & size of
source and volume, shape composition & distance from the source.
For β-particles, α-particles, X-rays and γ-rays less than 11KeV
and target volume larger than 1cm then φi = 0 unless in case of
source & target are same, φi = 1
For remaining all situations, φi lies between 0 to 1
It is difficult to evaluate these values. Thus Monte Carlo methods
are used and tabulated by Society of Nuclear Medicine.

20. Internal Dosimetry
 A unified approach to internal dosimetry was published by the
MIRD Committee in 1968, as MIRD Pamphlet No. 1, which
was updated several times thereafter.
 The latest publication on the formalism was published in 2009
in MIRD pamphlet No.21, which provides a notation meant to
bridge the differences in the formalism used by the MIRD
Committee and the ICRP.
 The MIRD formalism gives a framework for the calculation of
the absorbed dose to a target region from activity in a source
region is
Where
à = Cumulative Activity (μCi.hr)
S = Mean Absorbed dose/Cumulative activity (rad/μCi.hr)
S.A
~
Drad 

21. Internal Dosimetry
The Cumulative Activity (Ã) is represented by the area under the time
activity curve (or) The time integrated activity equals the no. of
decays that take place in a certain source region.
à = 1.44 A0.Te.f
Where,
A0 = Initial Activity before administration
Te = Effective Half Life
f = fraction of activity localized in organ
Models of Cumulative Activity:
 Uptake of source is instantaneous with no biologic excretion
 Uptake by organ is instantaneous with elimination by biologic
excretion only
 Uptake by organ is instantaneous with removal by both
physical decay and biological excretion
 Uptake by organ is not instantaneous

22. Internal Dosimetry
The Residence time (or) Time Integrated Activity co-efficient is
defined as the time-integrated activity divided by the administrated
activity
In other way, the area under the curve describing the activity as a
function of time equals the area for the rectangle.
ã = Ã/A0
ã = 1.44 A0.Te.f /A0
ã = 1.44 Te. f (total activity located at source t=0)
This can be described as an
average time that the activity
spends in source region

23. Internal Dosimetry
S - Mean Absorbed dose/Cumulative activity is defined as the ratio
of product of equilibrium dose constant & absorption fraction to
target mass
 S value for a certain radionuclide and source-target combination is
generated from Monte Carlo simulations in a computer model of
the anatomy.
 Earlier, in coordinate system simple geometrical shapes such as
spheres or cylinders were placed to represent important structures
of the anatomy for S value calculations
 Next, voxel based phantoms from tomo-graphic image data, used
for the calculation of S values.
 The phantom , created using non-uniform rational B-spline
(NURBS) is used to represent surfaces, is used for S values
m
)rv(
S
n
1i
ii



24. Pediatric Doses:
The metabolisms, bio-
distribution and excretion of
drugs are different in children
from in adults, thus dosages
for children must be adjusted
Several methods &
formulas have been reported
on pediatric dosage
calculations based on body
weight, body surface area,
combination
Weight in
kg (lb)
Fraction
Weight in
kg (lb)
Fraction
3(6.6) 0.1 28(61.6) 0.58
4(8.8) 0.14 30(66.0) 0.62
8(17.6) 0.23 32(70.4) 0.65
10(22.0) 0.27 34(47.8) 0.68
12(26.4) 0.32 36(79.2) 0.71
14(30.8) 0.36 38(83.6) 0.73
16(35.2) 0.4 40(88.0) 0.76
18(39.6) 0.44 42(92.4) 0.78
20(44.0) 0.46 44(96.8) 0.8
22(48.4) 05 46(101.2) 0.83
24(52.8) 0.53 48(105.6) 0.85
26(57.2) 0.56 50(110.0) 0.88
Internal Dosimetry

25. Internal Dosimetry
Assumptions & Limitations of MIRD formula:
 Assumptions are made that
 The activity distribution in the source region is assumed to
be uniform
 The mean absorbed dose to the target region is calculated
 MIRD formalism dose not set any restrictions on either
volume or shape of the source or target as long as uniformity
can be assumed
 MIRD implementation is simple and ease of use
 Major limitation is that the absorbed dose may vary throughout
the region

26. Internal Dosimetry
Assumptions & Limitations of MIRD formula:
 The Activity distribution is seldom completely uniform over
the whole tissue.
 The non-uniformity in the activity distribution can be overcome
by redefining the source region into a smaller volume.
 MIRD formalism utilizes the concept of cumulated activity,
defined as the total number of decays during the time of
integration.
 For practical application, heterogeneities or source distribution
within organs are neglected.

27. Internal Dosimetry
Therapy Level Organ rad/mCi mSv/MBq
131 I – Iodide (10 mCi) Thyroid 13000 3510
Stomach 14 3.78
Ovaries 1.4 0.378
131 I – Iodide (29 mCi) Thyroid 37700 10200
Stomach 40.6 11
Ovaries 4.1 1.11
Testes 2.6 0.7
131 I – Iodide (150 mCi) Thyroid 39000 10500
Stomach 255 68.9
Liver 30 8.1
Marrow 21 5.67
Ovaries 21 5.67

28. Internal Dosimetry
Therapy Agent Organ rad/mCi mSv/MBq
32 P – Phosphate Bone Marrow 37.0 10
Red Bone
Marrow
28.1 7.6
89 Sr – Chloride Bone Surface 63.0 17.0
Red Bone
Marrow
40.7 11.0
LLI 17.4 4.7
Bladder 4.8 1.3
Kidneys 3.0 0.8
153 Sm – EDTMP Bone Surface 25.0 6.8
Red Bone
Marrow
5.7 1.5
Bladder Wall 3.6 1.0

29. Dose Calibration
 It is important to measure the activity to be administrated to the
patient in prior to achieve therapeutic effect without excessive
radiation burden
 Dose calibrators are used in Nuclear Medicine dept which
indicates the activity to be administrated to the patient
 Before dose measuring, it is mandatory to check for
contamination of the chamber
 Background radiation adjustments should perform
 To check changes in calibration or malfunction of the dose
calibrator, a source of known activity (137Cs) is measured to
compare measured & calculated activity (5% difference is
acceptable)

30. Designing a Nuclear Medicine Dept
An approved nuclear medicine department, a qualified nuclear
medicine physician and a RSO are the prerequisites for any
radionuclide therapy program
The administration of therapeutic doses of radio nuclides must be
under the responsibility of a Physician who is licensed under
national regulations
While designing therapy room, the factors to be considered are:
Type of radionuclide is used and its energy
potential for contamination and degree of hazards
Type of waste generated and the way they should be handled
Requirements:
Patients must be housed in isolated room with dedicated
washroom
Access to the treatment room must be controllable

31. Designing a Nuclear Medicine Dept
Any required shielding must be designed for proposed floor plan
A non-porous, easily decontaminated floor and wall surfaces with
coved junctions to make cleaning easier
A minimum projections to prevent dust collection
A dedicated shower & toilet, draining directly to the main sewer
or delay tank depending on local regulatory requirements
A physical barrier to entry
Moveable lead shields to minimize nursing exposures
Possible installation of remote patient monitoring system
Door signs prohibiting entry to pregnant women, children and
other persons without permission, limiting visiting hours

32. Radiation Protection
Radio Nuclides must be used in strict accordance with safety
measures and any special instructions and all precautions must be
taken to avoid un-necessary exposure to radiation
Use of disposable gloves, gowns etc.,
While discharge of patient, patient belongings must be surveyed
for contamination
The patient must aware of information related to radio-nuclide
administration prior to treatment
131I therapy doses usually given in liquid or capsule form. The
patient is required to swallow the capsule without chewing
followed by a drink of water
A prophylactic anti-emetic should be given prior to or
immediately after the dose is administrated to avoid vomiting

33. Radiation Protection
A decontamination kit should always be available in the
treatment room in order to deal with the spillage.
Beta emitters such as 89Sr and 32P, generally require consideration
only at the time of administration
Following administration the injection site must be checked for
spilt or leaked radio nuclide by swabbing and checking the swab
with a beta detector
Most of the excretion occurs in the urine, significant
contamination in saliva, less in sweat etc.,
To stimulate the excretion, patients should be advised to drink
freely and void frequently
Patients should be advised to flush the toilet twice after voiding
The precautions may usually be discontinued after 72 hrs

34. Radiation Protection
The rooms where work with unsealed sources are taken places
should be under negative pressure to minimize the risk of air-borne
radio nuclide to be spread
Always open vials in fume hood. Avoid direct handling of vials.
Use forceps with rubber grips
Cap tightly vials when not in use
Movement of radio nuclide must be minimized
Effective dose to patient’s comforter shall not normally exceed
5mSv during the period of patients treatment
After discharge, family members dose other than comforter does
not exceed 1mSv/Year (estimated)

35. Radiation Protection
Spillage Management:
Radio active spills should not be treated as events completely
without hazard even though those are not life threatening
Spillage occurs in radio active solutions can spill in transit, inside
containers, during preparations, QA, while loading syringes or
while injecting patients etc.,
Two types of spills:
Major Spills
Minor Spills
There is no definitive distinction exists between these two spills

36. Radiation Protection
Spillage Management:
Minor spills represent the release of several micro curies (over
100 kBq) of radio activity
The person involved
Warns other workers
 wearing gloves, proceeds to decontaminate the area
immediately
Inform RSO
RSO has to prepare an incident report for the files

37. Radiation Protection
Spillage Management:
Major spills involve the release of several milli Curies (over
100MBq) of radio activity
The person involved:
Warns other workers
Closes the area to traffic
Summons the RSO who immediately assesses the situation
and gives direction for decontamination
An assessment of the quality & quantity of radioactive spilled
is made
The area covered by spill is recognized by monitoring. If any
worker is injured, medical assistance is requested immediately.

38. Radiation Protection
Spillage Management: Major Spills
Wearing protective clothing, the worker proceeds to pick up
most of spilled solution with absorbent paper towels held with
18 inch forceps.
Pick up procedure: spiral in technique. Wipe with paper
towels starting at the periphery and in a circular motion toward
the center of the area.
Heavy duty plastic bags use to sent to decay in storage
Cleaning solutions are then used to decontaminate the area
Monitoring of the area with a surface monitor will confirm
complete decontamination less than 2mR/hr (0.2 μSv/hr)
RSO prepares incident reports to the radiation safety
committee and makes recommendations to prevent future spills.

39. Radiation Protection
Waste Management:
Each type of waste should be kept in separate containers that are
properly labeled
Waste should be properly packed in order to avoid leakage during
storage
The final disposal of the radio active waste produced in the NM
facility includes:
 Storage for decay (applicable only for radionuclides with less
than 120 days half life, until decay to 10 half lives of activity and
monitor before disposal)
 Disposal as cleared waste into the sewage system,
 transfer to authorized recipient
 Other disposal methods approved by the NRC (incineration of
solid waste and atmospheric release of radioactive gases)

40. Radiation Protection
Emergency Management:
Medical event occurs when a dose exceeds 5rem (0.05Sv)
effective dose equivalent, or 50rem (0.5Sv) to an organ or tissue or
skin from any of the following situations.
 Total dose delivered differs from prescribed dose by 20% or
more
 Total dosage delivered differs from the prescribed dosage by
20% or more, or falls outside the prescribed dosage range
 Administration of a wrong radioactive drug containing by-
product
 Administration by wrong route
 Administration to a wrong individual

41. Radiation Protection
Emergency Management:
The licensee must notify by phone to competent authority no
later 24 hrs after the discovery
Written report to the competent authority within 15 days which
includes brief description of the event, cause of the event, effect of
the event, corrective action taken if any, and whether the affected
individual or his or her relative or guardian has been notified etc.,
An emergency preparedness program should be available in the
institute to handle above mentioned situations

42. Radiation Protection
Surface contamination with radioactivity could lead to
contamination of a radiation worker and/or external irradiation of
the skin of the worker.
The surface contamination limits were derived based on a
committed effective dose limit of 20 mSv/year.
Contamination should check with contamination monitor with
appropriate probe detector.
Nuclide Surfaces in designated
areas (including protective
clothing ) (Bq/cm2)
Interiors of glove
boxes and fume
cupboards (Bq/cm2)
Non Designated areas
including personal
clothing (Bq/cm2)
131I 100 1000 5
89Sr 100 1000 5
32P 100 1000 5
99mTc 1000 10000 50

43. Radiation Protection
If any difficulty found while measuring low beta emitter present
in area, wipe test should be used
100cm2 should be wiped and activity on the wipe assessed.
Usually do dry wipe which will remove 1/10th of contamination
where as wet wipe removes 1/5th of the contamination
A ring monitor at the base of the middle is used to assess the
finger doses
The detector element positioned on palm side estimated dose to
the tip. If detector is worn facing towards the back of the hand, a
factor of 6 should be applied

44. Radiation Protection
Classification of Hazards:
This is done based on calculation of a weighted activity using
weighting factors according to radio nuclide and type of operation
performed
According to sources:
Class A sources : 131 I, 125 I, 89 Sr, 75 Se ==> weighting factor : 100
Class B sources: 99m Tc ==> Weighting factor : 1.00
Class C sources: 3H, 14C ==> Weighting factor : 0.01
According to type of work:
Storage ==> weighting factor : 0.01
Waste handling, imaging room, patient bed ==> Weighting Factor : 0.1
Radionuclide Administration ==> Weighting Factor : 1
Complex Preparation ==> Weighting Factor : 10

45. Radiation Protection
Classification of Hazards:
Ex: Administration of 400MBq 131I
Weighting factor of administration : 1
Weighting factor of 131 I : 100
Source activity : 400MBq
Weighted Activity : 1 x 100 x 400 = 40000MBq
==> Medium Hazard
Weighted Activity Category
< 50MBq (1.35mCi) Low Hazard
50 to 50000MBq (up to 1.35Ci) Medium Hazard
>50000MBq (>1.35Ci) High Hazard

46. Radiation Protection
Monitoring after Receiving of Radionuclide:
Monitoring of packages is required to check if the packages are
damaged or leaking
Monitoring must be done as soon as possible after receipt but not later
than 3 hr after delivery.
Two types of monitoring : survey for external exposure and wipe test
for contamination on the surface of the package
The survey reading of external exposure should not exceed
200mrem/hr (2mSv/hr) on the surface of the container or 10mrem/h
(100μSv/hr) at 1 meter from the surface of the container
The wipe test is performed by swabbing an area of 300cm2 of the
package and should not exceed of 6600dpm or 111MBq/300cm2.
All surveys are data must be logged in includes the date of receipt, the
manufacture, the lot number, name and quantity of the product, date and
time of calibration and survey data etc.,

47. Radiation Protection
Precautions following death of a therapy patient:
The procedures like labeling, contamination avoidance and
notification of the staff who may have to handle the body, should
be put in place
The procedures will depend on the radio nuclide involved, the
dose and time since administration etc.,
The sheet in which the body is wrapped should be clearly visible
to all those handling the body
During cremation, prior authorization and specific safety
precautions to be followed must be obtained from RSO.
The RSO shall recommend methods on dose reduction to the
personnel involved.

48. Radiation Protection
If a corpus contains less than
150MBq (4mCi) of colloidal 90Y
300MBq (8mCi) of 32P
450MBq (12mCi) of 131I
Normal procedures are adequate for examination
If a corpus contains radioactivity in excess of above mentioned
levels, the pathologist should be informed of the radiation levels
likely to be encountered and of the hazards involved.
In such cases, precautions need to be taken
No special precautions are necessary for the cremation of corpus
containing not more than 1000MBq (30mCi) of 90Y, 89Sr and 131I
(or) 400MBq (10mCi) of 32P

49. Radiation Protection
Prevention of Internal Contamination:
Internal contamination is possible by ingestion, inhalation,
percutaneous absorption or by accidental injection
There should be no eating, drinking, or using cosmetics in the
working areas of the NM dept
Any kind of radio active things should not brought into the
lounge room, waiting room etc.,
Some volatile radio activities (131I and 125I) could be released
accidentally.
All preparations are to be done in a properly operating fume hood
or glove box. The exhaust must be equipped with sodium
hydroxide solution traps to catch any volatile radio-iodine. Any
liquid waste must be dumped in a container with some strong
NaOH solution and kept covered

50. Radiation Protection
Prevention of Internal Contamination:
To avoid percutaneous absorption, long-sleeved coats, gloves,
masking tapes around the wrists to seal the gap between the gloves
and the lab coat sleeves, transparent plastic shields in front of the
face, and lead glass glasses are recommended when handling these
nuclides in liquid form.
If the contamination of the skin does occur accidentally, the
contaminated clothing must be removed immediately, and
decontamination of the skin with soap and water must follow. This
is followed by proper monitoring to ensure successful
decontamination

51. Radiation Protection
Bio-Assay of Radioactivity: For Occupational worker
Radio-bioassays are laboratory tests that quantify the accidental
intake of radioactivity in the body of radiation workers
In this method samples are collected from person and analyzed to
measure the contamination
Regulations require that the person intake of radioactivity and
assess the committed effective dose likely to receive more than
10% of the ALI
Nuclide ALI (Ingestion)
(μCi)
ALI (Inhalation)
(μCi)
DAC (inhalation)
(μCi/ml)
125I 4 x 101 6 x 101 3 x 10-6
32P 6 x 103 3 x 103 1 x 10-6
131I 9 x 101 5 x 101 2 x 10-8

52. Radiation Protection
Patient discharge:
Patients may be discharged only when the remaining activity is
less than that prescribed by the local regulatory authority
(555MBq/15mCi)
Patient monitoring should be done with survey meter at 1meter
distance from the patient
On discharge patients must be given instructions such as maintain
distance from others, sleep alone, do not travel by airplane or mass
or mass transportation, regarding contact with children and adults,
breast feeding and toilet use etc.,
Radionuclide Activity remaining
(GBq (mCi))
Dose rate at 1m
(μSv/hr) (mR/hr)
I – 131 1.1 (30) 50 - 60 (5 - 6)
P – 32 No practical limit Not applicable
Sr – 89 No practical limit Not applicable

53. Conclusion
In any radionuclide therapy program, proper implementation
of radiation safety measures and the cardinal principles of
Time, Distance & Shielding can kept exposure to patient,
nuclear medicine physician, nurses, staff and public
As
Low
As
Reasonably
Achievable

54. Thank you…