Transcript Slide 1

Barcelona, 20-22 January 2011
MODULE FOR NUCLEAR MEDICINE
Prepared by:
Marta Sans-Mercè
University Hospital Center and University of Lausanne,
Switzerland
Mercè Ginjaume
Universitat Politècnica de Catalunya, Spain
This training material has been developed in the framework of the
Research project ORAMED, Optimization of Radiation Protection
of Medical staff, funded by the European Atomic Energy
Community's Seventh Framework Programme (FP7/2007-2011)
under grant agreement n° 211361.
Workshop on optimization of Radiation Protection of Medical Staff
ORAMED SPECIFIC TRAINING
USE AND DISCLAIMER

This is a PowerPoint file.

It may be downloaded free of charge.


It is intended for teaching and not for commercial
purposes.
It is based on the results and guidelines derived
from the “ORAMED, Optimization of Radiation
Protection of Medical staff” project, funded by the
European Atomic Energy Community's Seventh
Framework Programm.
Objectives
Framework: it is based on lessons learned from the ORAMED project,
it mainly concentrates on extremity dosimetry in nuclear medicine
After the training participants should be able to
1.- know the physical characteristics of the different sources of
exposure in nuclear medicine and the limits of exposure.
2.- identify the organs at risk for the different diagnostic/
therapy procedures.
3.- recognize and apply radiation protection means to ensure an
adequate protection of staff.
4.- select the best dosimetric system and to implement the best
monitoring procedure (type of dosemeter, position of use,
interpretation of dosemeter reading).
5.- identify good and bad practices, in order to adapt, if needed,
changes in the procedures, to improve the daily practice.
General structure
1.- Introduction/revision: (what should be known: Aims of the
medical speciality, different types of procedures, types of radiation
sources, characteristics + workers dose-limit)
2.- Radiological risks (based on ORAMED results, the critical
procedures, organs at risk and associated doses are highlighted).
3.- Staff monitoring: available dosemeters (Different types of
available dosemeters together with the recommendations on their use
depending on the type of procedure are presented).
4.- Radiation protection means (Based on ORAMED measurements
and simulations results, a description of available RP means,
shielding, type of syringe, distance, time are shown; first
recommendations are presented).
5.- Guidelines, recommendations to optimize radiation protection
(summary of previous observations)
To confirm knowledge, several questions are introduced in
the presentation. When available they can be used with
interactive systems.
CHAPTER 1:
INTRODUCTION /
REVISION
Nuclear medicine definition
Nuclear medicine is a branch of
medicine dealing with the use of
(un-sealed) radioactive materials
in the diagnosis and treatment of
disease.
Ref: Merriam-Webster's Medical Dictionary, © 2007 Merriam-Webster,
Inc.
Most common radionuclides in nuclear medicine
For diagnostic
Gamma emitters
99mTc, 111In, 123I, 131I, 201Tl, 133X,
…
+ emitters (and annihilation photons)
18F, 11C, 13N, 15O, (64Cu, 82Rb, 86Y, 124I,
…)
For therapy
- emitters
90Y, 131I, 32P, 89Sr, 153Sm, 169Er, 177Lu, 186Re,
…
Characteristics of the most frequently used
radionuclides
 Diagnosis with Tc-99m and F-18
 Therapy with Y-90 (RIT with Zevalin®; PRRT with Dotatoc®), I-131
Tc-99m
Pure g-emitter
Eg = 140.5 keV (87%)
F-18
Y-90
+-emitter
Mixed g- and
Eg = 511 keV (194%)
E+max = 634 keV (97%)
Pure --emitter
E-max = 2280 keV (100%)
-
+
Y-90:  spectrum
Eg = 365 keV (82%)
E-max = 606.3 keV(89%)
0.09
0.08
0.08
0.07
0.07
0.06
Probability (a.u.)
I-131
Mixed g and  emitter
Probability (a.u.)
F-18:  spectrum
0.06
0.05
0.04
0.03
0.02
0.05
0.04
0.03
0.02
0.01
0.01
0.00
0.00
0.0
0.1
0.2
0.3
0.4
Energy (Mev)
0.5
0.6
0.7
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Energy (MeV)
Radionuclides characteristics
Q1. Typical activities per patient per diagnostic procedures are
of the order of 500 MBq for Tc-99m, 400 MBq for F-18.
For Y-90 therapy the activity is 1 GBq.
Which is the dose rate in contact of a 5 ml unshielded syringe?
A. The lowest dose-rate is for Y-90.
B. For Y-90 is 34 times larger than for Tc-99m and 5 times
larger than for F-18.
C.
The largest dose-rate is for F-18.
D. The largest dose-rate is for Y-90, then for Tc-99m and finally
for F-18.
Dose rate at contact
Contact of an unshielded (5 ml) syringe
Hp(0.07) rate (in mSv.min-1)
700
1000.0
20
10
167
100.0
100
min
-1
1000
mSv.min
Time (in min) to reach 500 mSv
3
25
10.0
0.7
1.0
1
0.1
Tc-99m
500 MBq
F-18
400 MBq
Y-90
1 GBq
Tc-99m
500 MBq
F-18
400 MBq
 Dose rates are VERY different
 For Y-90 the annual limit can be reached in less than 1 minute
 Shielding is essential
 However, the frequencies of use are VERY different
Y-90
1 GBq
Radionuclides characteristics
Q2. As regards the range/penetration of the most typical
radiopharmaceuticals.
Which is the correct statement?
A. The half-value layer in tissue of F-18 is of the order of 7.5 cm.
.
B. The half-value layer in tissue for Tc-99m is of the order of 2 cm.
C.
The range of Y-90 in tissue is of the order of 5 cm.
D. The range of Y-90 in air is of the order of 10 cm.
Properties of the most common radionuclides
Nuclide
Gamma
energy (keV)
HVL in tissue
(cm)
140.5
4.6
511
7.5
Tc-99m
F-18
(annihilation
photons)
x1.6
Max Eß
(MeV)
Mean Eß
(MeV)
Max. range
in tissue
(mm)
Y-90
2.3
0.9
11
F-18
0.63
0.25
2.3
Nuclide
Dose limits
Q3. As regards the dose limits for extremity dosimetry in
nuclear medicine
Which is the correct statement?
A. No need for routine extremity monitoring , dose limit is never
reached.
B. The annual dose limit for the skin is 20mSv averaged
over 1cm2
C.
The annual dose limit for the skin is 500mSv averaged over
1cm2
D. The annual dose limit for the skin is 500mSv averaged
over the hand
Dose limits for the extremities
ICRP 60 recommendations :
Annual equivalent dose in the skin
500mSv for 12 months averaged over 1cm2 area
regardless of the exposed surface
European directive 96/29:
All workers likely to receive an extremity dose larger
than 3/10 of the annual limit dose must wear an
extremity dosemeter
CHAPTER 2:
RADIOLOGICAL RISKS
Staff
Radiological risks: Sources of exposure of nuclear
medicine workers
Nuclear medicine implies the manipulation of
unsealed radioactive sources
Risk of internal contamination
•Valid for all radionuclides and specially for iodine (volatile)
and ...
D0 / 202
Radiological risks: Sources of exposure of nuclear
medicine workers
Risk of external irradiation
• Whole body (WB) and extremities irradiation when manipulating
radioactive sources
Generator
Elution vial
Labelling with Tc-99m
Labelling vial
Injection in diagnostics
The hands are particularly exposed in nuclear medicine
• Whole body irradiation
from the patient
Radiological risks
Q4. As regards nuclear medicine technologists’ annual dose, the
main source of exposure, compared with annual limits is
related to :
A.
The WB exposure during preparation and administration of
radiopharmaceuticals.
B.
The WB exposure when assisting and accompanying the patient.
C.
The extremity exposure during preparation and administration
of radiopharmaceuticals.
D.
The extremity exposure when assisting and accompanying the
patient.
WB doses expected (external radiation)
Technologist Dose per procedure (mSv)
WB Tc-99m bone scan
0.3 ± 0.2
Tc-99m MIBI SPECT
1.7 ± 0.2
WB FDG
5.9 ± 1.2
Typical annual whole body staff doses at
conventional Nuclear Medicine facilities are 0.1 mSv,
but are closer to 6 mSv at PET/CT facilities. While a
substantially higher dose, this is still below the ICRP
limit of 20 mSv per year
Source: IAEA teaching slides - Radiation Protection in PET/CT
Is it easy to exceed the skin dose limit?
2400
Maximum annual dose (mSv)
2200
2000
Tc-99m
administration
Tc-99m
preparation
F-18
administration
F-18
preparation
1800
1600
1400
1200
D < 150 mSv  34%
D < 150 mSv  13%
150 mSv < D < 500 mSv  39%
150 mSv < D < 500 mSv
 43%
150 mSv < D < 500 mSv
 47%
D > 500 mSv  8%
D > 500 mSv  23%
D > 500 mSv  40%
D < 150 mSv  72%
D < 150 mSv  53%
150 mSv < D < 500 mSv  28%
D > 500 mSv  0%
1000
800
600
400
200
0
Procedure
Range
(µSv/GBq)
Mean
(µSv/GBq)
Tc-99m administration
12 – 951
233
Tc-99m preparation
33 - 2062
432
F-18 administration
139 - 4113
933
F-18 preparation
97 - 4433
1205
Patients per
year
1000
(5 patients
per day, 10
months)
Activity per
patient (MBq / mCi)
100 – 850 / 3 – 30
Mean: 500 / 14
Annual dose (mSv /
% limit)
117 / 23%
216 / 43%
400 / 11
373 / 75%
500 / 14
603 / 121%
 Depending on the workload, the skin dose may surpass the
dose limit or 3/10 of the limit, especially for F-18.
Source: ORAMED - Carnicer et al. Radiat. Measurements, 2012.
Radiological risks
Q5. What are the procedures at risk for nuclear medicine
technologists in diagnostic nuclear medicine, regarding the
doses to the extremities?
For the same activity, the maximum skin dose...
A.
Is usually higher for the preparation of Tc-99m than for
the administration of F-18.
B.
Is usually higher for the preparation of F-18 than for
the administration of F-18.
C.
Can be higher for the preparation of Tc-99m than for the
preparation of F-18.
D.
All are correct.
Max norm. dose (µSv/GBq)
Comparison of diagnostic NM procedures
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Preparation
Administration
Tc-99m
Preparation
Administration
F-18
 Very large range of maximum finger doses.
 The preparation of the radiopharmaceutical involves higher finger
doses per activity than the administration.
 F-18 involves higher finger doses per activity than Tc-99m.
 The preparation of F-18 is the most critical among the studied
diagnostic procedures.
Source: ORAMED - Carnicer et al. Radiat. Measurements, 2012.
Contamination
Y-90 Zevalin® - Therapy
Attention with
contamination,
in particular for
therapy
Dose rate > 200mSv/h
approx. 5cm over the
contamination spot
Source: Ilona Barth and Arndt Rimpler
CHAPTER 3:
STAFF MONITORING
24
Measuring internal contamination
In vitro
measurement
- (or a)
(therapy)
Liquid scintillation
counting
g (and +)
(imaging)
In vivo
measurement
Whole body
counter (WBC)
25
Routine external monitoring
Routine whole body monitoring with TLDs
Quantity to be measured Hp(10)
Extremity routine monitoring with TLDs
Quantity to be measured Hp(0,07)
In practice ring or wrist dosemeter are used
Should be worn at the most exposed position in the hands
26
Type of TLD
 Whenever one can be sure that the workplace does not include lowenergy beta particles, the use of TLD-100 would be advisable because of
its better performance and ease of use (1).
If the contribution of positrons to Hp(0.07) for PET workers cannot be
neglected. Thin TL detectors, such as MCP-Ns, are more appropriate for
this type of dosimetric application. If thin TL detectors are not used, an
underestimation of the order of 30% could be envisaged for 18F handling.
This difference should be added to the underestimation of Hp(0.07)
because of the position of the dosemeter (2).
(1) Ginjaume et al. Comparison of two extremety dosemeters based on LiF:Mg,Cu,P thin detectors for
mixed beta-gamma fields. Radiat. Prot. Dosim. 120, No. 1-4, 316–320 (2006).
(2) Ginjaume et al. Comparison of TLD-100 and MCP-Ns for use as an extremity dosemeter for PET nuclear
medicine staff. Radiat. Prot. Dosim. 43, 607–610 (2008).
27
Staff monitoring
Q6. Which statement would you consider if you were to
recommend some type of extremity dosemeter for nuclear
medicine workers?
A.- The ring dosemeter always provides a higher dose reading. Use a
ring dosemeter.
B. – You can use either a ring or a wrist dosemeter. But it is important
to use 2 dosemeters.
C.- There are no significant differences between wrist and ring. Use a
wrist dosemeter in the dominant hand (right) because it is more
confortable.
D.-There are no significant differences between wrist and ring. Use a
wrist dosemeter in the non dominant hand (left).
28
Doses at different positions
Doses at wrist
position are
systematically
lower than at
any other
position
29
Staff monitoring
The ring dosemeter is recommended to the wrist
dosemeter in nuclear medicine.
Q7. In which position should it be worn?
A. Base of the ring finger of dominant hand (external side)
B. Base of the ring finger of dominant hand (palm side)
C. Base of the index finger of non-dominant hand (external side)
D. Base of the index finger of non-dominant hand (palm side)
30
Staff monitoring
The ring dosemeter should be worn as close as possible to the
most exposed part of the hand. However this is not easy to do in
practice.
Q8. How much do you underestimate the maximum skin
dose when monitoring it with a ring dosemeter worn in the
base of the index (palm side) non-dominant hand?
A. You don’t underestimate.
B. Up to a factor of 2
C. Around a factor of 6
D. Around a factor of 10
E. Up to a factor of 100 when you manipulate beta sources.
31
Ratios for diagnostics procedures
 General ratios considering all data independently of the procedure.
30
144
61
38
72
49
3.1
2.5
(all data)
25
5.5 10
20
9.4 6.0
15
10
5
0
(outliers
excluded)
<max / <max /
wrist>
base
index>
<max / <max / <max / <max / <max / <max /
base
index WRIST> BASE
BASE
INDEX
ring>
tip>
INDEX> RING>
TIP>
ND hand

22
18
D hand
The recommended monitoring position is the base of the index finger of
the ND hand (low ratio, high correlation with the maximum) which
underestimates the maximum dose by a factor of 5.5.
•
Source: ORAMED - Carnicer et al. Radiat. Measurements, 2012.
Ratios for therapy procedures
2
7
14
15
20
30
22
17
•The recommended position is the base of the index finger of the ND
hand (low ratio, high correlation with the maximum) which
underestimates the maximum dose by a factor of 7.
Source: ORAMED - Rimpler et al. Radiat. Measurements, 2012.
CHAPTER 4:
RADIATION PROTECTION
MEANS
34
Radiation protection means
How to reduce the skin dose?
Q9. What are the 3 most important parameters (in
order of importance) influencing the maximum skin
dose in nuclear medicine?
A.
Distance – Shielding – Dose monitoring
B.
Distance – Time – Shielding
C.
Shielding – Distance - Training
D.
All of the above
35
3 basic principles in Radiation protection
• Shielding
•Distance
•Time
(training)
36
Shielding
Personal Protective
equipment
Syringe shield
Vial Shield
Lead gloves
Room Protective Equipment
Lead box
Activimeter in the lead box
37
Y-90 Zevalin® dose
rate during the
injection trough a
flexible tube
RSO with Y-90,
dose rate
reduction when
using adapted
tools.
Source: Ilona Barth and Arndt Rimpler
38
Radiation Protection means
Q10. Concerning shielding when injecting a
radiopharmaceutical....
A. All shieldings have the same reduction factor
independently of the radionuclide
B. No need of shielding since the injection procedure
is fast
C. 2mm Tungsten and 3 mm lead are equivalent for
99mTc
D. 5mm of tungsten is the minimum required
shielding 99mTc
39
Injection scenarios
Tc-99m
Tc-99m:
2 mm W provide about more than 2 orders of magnitude
of attenuation
There is little differences between Pb and W, even if W if better
performing (because of specific density 11.35 versus 19.3 g/cm3)
Source: ORAMED project.
40
Injection scenarios
F-18
F-18:
(best is 8 mm W) 5 mm W provide a factor of 10
Source: ORAMED project.
41
Injection scenarios
Y-90
For Y-90 5 mm W is
better than 1 cm
PMMA providing more
than 3 order of
magnitudes of
attenuation. W shields
also Bremmsstrahlung
radiation.
Source: ORAMED project
42
Preparation scenarios
Tc-99m
3 mm Pb provides more than 3 orders of
magnitude in dose reduction.
Source: ORAMED project
43
Preparation scenarios
F-18
3 cm Pb provides 2 orders of magnitude in dose
reduction
Source: ORAMED project
44
Preparation scenarios
Y-90
5, 10 and 15 mm of
PMMA provide
almost the same
attenuation.
To further reduce
the doses at least
some mm of Pb are
needed.
5 mm W can be
directly used instead
of using PMMA +
Pb.
Source: ORAMED project
45
Summary shielding recommendations
For the injection (syringe shielding):
 2 mm W (or Pb) for Tc-99m give a dose reduction of at least 2 order
of magnitudes;
 5 mm W provides up to a factor 10 in dose reduction for F-18 (8 mm
W up to a factor 40).
 For Y-90 10 mm PMMA completely shield beta radiation,
nevertheless 5mm shielding of tungsten provides a better shielding
cutting down bremsstrahlung radiation too.
For the preparation (vial shielding):
For F-18, 3 cm of Pb provides 2 order of magnitudes on dose
reduction. The same attenuation for Tc-99m is obtained with 2 mm Pb.
 For Y-90 an acceptable shielding is obtained with 10 mm PMMA
with an external layer of few mm of lead or alternatively 5 mm of W.
46
Distance
Distance
Automatic dispensers
Twisers/Forceps
47
Tools - forceps
F-18 vial source shielded with 8 mm
W.
the effectiveness of
using forceps is also
demonstrated when
working with shielded
sources.
48
Radiation Protection means
When handling an Y-90 syringe for RTPE the position of the
fingers is very important. The dose rate along the syringe
varies dramatically..
Q11. How many times can the doses at the fingers be
reduced if the contact with the shielded syringe is in
position A (no pharmaceutical, below)?
C
A.
More than 1500 from B to A
B.
Up to a factor of 100 times from B to A
C.
Up to a factor of 1000 times from C to A
D.
More than 10000 times from C to A
E.
(A) and (D) are correct
B
A
49
Dose rates (in mSv/h) at the different
positions in a syringe filled with Y-90
50
Time
It is very difficult to correctly estimate the
influence of time to a complete procedure,
especially for the preparation of radiopharmaceuticals.
(Different steps, very different dose rates in each
step, usually for trained workers, the use of shield
or the distance are parameters more
determinant).
51
Radiation Protection means
Q12. How many years of experience a worker needs to
keep his annual maximum hand dose below the annual
limit of 500mSv?
A.
More than 1 year
B.
After 6 months the worker has acquired enough experience
C.
Minimum 5 years
D.
The experience is not always related to low doses
52
1200
900
800
700
Not statistically significant
differences
1000
800
600
1000
Administration of Tc-99m
Few data
600
500
400
300
200
4000
400
Unshielded syringe excluded
3500
200
500
0
0
3000
2500
100
500
0
0
T4HF9
T4HG5
T3HF9
T3HG5
T1HB1
T5HF2
T1HD1
T2HB3
T6HE1
T1HB3
T7HB1
T1HF10
T7HE1
T4HF1
T1HG2
T6HA2
T7HF6
T10HF1
T1HE3
T1HF8
T1HD2
T2HA2
T1HF6
T1HA1
T2HE2
T2HG2
T3HE3
T2HA1
T2HF8
T5HE2
1400
Unshielded vial excluded
T10HE1
T9HE1
T2HG5
T1HG5
T2HB3
T3HF9
T2HB1
T1HB3
T5HF2
T7HF6
T4HF8
T4HB1
T1HD3
T1HF10
T3HF8
T4HF2
T7HA2
T1HE3
T2HE3
T5HA1
T6HA2
T1HD2
T4HA1
T4HG2
T1HF6
T2HD1
T4HE2
T6HE2
T3HG2
T5HD2
1600
Preparation of Tc-99m
Max norm dose (µSv/GBq)
2200
Max norm dose (µSv/GBq)
1800
T4HB3
T1HF1
T6HF7
T3HB3
T8HB1
T2HA2
T11HF2
T3HA2
T2HE2
T10HF1
T1HF7
T4HB1
T1HE2
T9HF2
T1HA4
T1HA1
T1HF3
T3HE1
T1HF8
T1HE1
T2HF9
T1HF9
T2HF4
T2HF8
T2HF6
T1HF4
T3HG3
T1HF6
T3HD2
T2HF12
T2HD4
T3HA1
T1HD1
T1HG3
T1HG4
T2HG4
Max norm dose (µSv/GBq)
2000
T2HG3
T6HB1
T9HB1
T1HF4
T1HF3
T3HB3
T4HB3
T3HA4
T2HF9
T3HF8
T4HE1
T8HA2
T2HE1
T1HA1
T2HF4
T10HF2
T3HF7
T3HG4
T5HF1
T13HF1
T2HE2
T2HD1
T3HA1
T4HF8
T6HF6
T1HD4
T6HD2
T4HG3
T4HG4
T1HE2
T7HD2
T1HF6
Max norm dose (µSv/GBq)
Experience: higher doses for beginners ?
4500
Preparation of F-18
Unshielded syringe excluded
3000
Few data
2500
2000
1500
1000
4500
4000
Administration of F-18
3500
Not statistically significant
differences
2000
1500
1000
 The influence of the experience on the dose is not clear
(few data, influence overlapped with other parameters).
53
 The accumulated dose is directly proportional
to the time. A reduction of 2 in time implies a
reduction of 2 in doses.
 Training is very important to ensure a quick
and correct handling of radiopharmaceuticals.
However, experience is not always related with
good training and good practice. There are cases
of bad habits.
54
CHAPTER 5:
SUMMARY
RECOMMENDATIONS
55
General observations
Wide ranges of individual exposures (min/max) for similar
procedures, different equipment, radiation protection
means and tools.
Skin dose limit (500 mSv/y) can be exceeded by numerous
workers in hospitals where RP standard is low
There is adequate potential to further improve radiation
protection and decrease exposures
Adequate skin dose monitoring is urgently needed in
nuclear medicine
56
What we have learned
The choice of TLD and TLD position is important for
an adequate dose assessment
Shielding of vials and syringes are essential and a
precondition but not a guarantee for low exposures.
Other RP tools and measures (e.g. pincers, forceps,
time etc.) significantly influence the exposure.
Also subjective factors e.g. risk awareness and
training affect exposures. Especially in therapy,
participants have reduced extremity dose during the
project due to the feedback of the measurement
results on the RP standard.
 Working fast is often not sufficient
57
Examples of good practices
Preparation of Tc-99m
Preparation of F-18
Administration of Tc-99m
Administration of F-18
58
Examples of good practices for Y-90
59
Examples of bad practices
Preparation of Tc-99m
Preparation of F-18
Unshielded vial and syringe
Unshielded syringe,
thumb direclty exposed
Administration of Tc-99m
Administration of F-18
Unshielded syringe
Left hand holding the part
of the needle
60
Examples of bad practices for Y-90
Example of bad RP practice
The maximum skin dose for
this worker is 52 times the
mean of the 30 participants
61
Examples of bad practices for Y-90
The maximum
skin dose for this
worker is 16
times the mean
of the 30
participants
T7HF
2
62
Outcome
The final outcome of the ORAMED project is to propose, on the basis
of the results of measurement and simulation campaign performed,
the guidelines in order to minimise radiation risk to medical staff in
nuclear medicine.
Directed to:
• physicians
• nurses
• technicians
• radiation protection officers
• authorities in the field
The following recommendations concern only radiation
protection aspects.
Recommendation 1 The annual dose of 60% of the
workers monitored for the
ORAMED project has been
estimated only considering the
procedures from which real
measured values were available
and only for those whom their
workload was known.
For diagnostics procedures:
•The annual dose estimation is
above 150 mSv (3/10 of the
annual limit) for 51% of the
workers.
• 20% of the workers exceed the
annual dose limit of 500mSv.
extremity monitoring
Extremity monitoring is a
necessity in nuclear
medicine.
Recommendation 2 -
routine monitoring
The base of the index finger of the non dominant hand
with the detector (TLD) placed towards the inside of
the hand is the recommended position for routine
extremity monitoring in nuclear medicine.
30
144
38
61
72
49
25
(all data)
20
15
10
5
0
Best monitoring position:
index tip of the non
dominant hand BUT not
feasible for routine
monitoring with ring
dosemeters
<max / <max / <max / <max / <max / <max / <max / <max /
wrist> base
base index WRIST> BASE BASE INDEX
index> ring>
tip>
INDEX> RING> TIP>
ND hand
D hand
Recommended monitoring position: base index finger of non
dominant hand with TLD directed to the inner side
•low ratio
• high correlation with the maximum
• comfortable for manipulating
Recommendation 3- estimation of maximum dose
A rough estimate of the maximum dose to the hand can
be obtained by multiplying the reading of the
dosemeter worn in the base of the index of the non
dominant hand by 6.
2.5
5.5
10
22
Diagnostics
9.4
18
3.1
2
6.0
7
14
15
20
Therapy
30
22
17
Recommendation 4 -
shielding
Shielding of vials and syringes are essential and a
precondition but not a guarantee for low exposures.
Recommendation 5 –
minimum syringe shield
The minimum acceptable shielding required for a
syringe is 2 mm of tungsten for 99mTc and 5 mm
of tungsten for 18F . For 90Y 10 mm PMMA
completely shield beta radiation, nevertheless
5mm shielding of tungsten provides a better
shielding cutting down bremsstrahlung radiation
too.
Recommendation 6 –
minimum vial shield
The minimum acceptable shielding required for a
vial is 3mm and 3cm lead for 99mTc and 18F
respectively. For 90Y an acceptable shielding is
obtained with 10 mm PMMA with an external
layer of few mm of lead.
Recommendation 7 –
training and education
Training and education on good practice (e.g. procedure
planning, repeating procedures using non radioactive
sources) are more relevant parameters than the
experience of the worker.
Procedure planning:
preparation of tools,
estimation of doses to be
received (dose estimation
tool), first trial with inactive
sources.
Recommendation 7 –
training and education
Dose estimation tool
Recommendation 8 –
radiation protection tools
All tools increasing the distance (e.g. forceps) between
the hand/finger and the source are very effective for
dose reduction.
the effectiveness of
using forceps is also
demonstrated when
working with shielded
sources.
Recommendation 9 –
time
Working fast is not sufficient, the use of shields or
increasing the distance are more effective than pushing
on the working speed.
It is very difficult to correctly estimate the influence of time on the
dose during a complete procedure, especially for the preparation of
radiopharmaceuticals.
Different steps, very different dose rates in each step, usually for
trained workers
the use of shields or increasing the distance are
more effective than pushing on the working speed.
Recommendations (summary 1/2)
1. Extremity monitoring is a necessity in nuclear medicine.
2. The base of the index finger of the non dominant hand with the detector
(TLD) placed towards the inside of the hand is the recommended position for
routine extremity monitoring in nuclear medicine.
3. A rough estimate of the maximum dose to the hand can be obtained by
multiplying the reading of the dosemeter worn in the base of the index of the
non dominant hand by 6.
4. Shielding of vials and syringes are essential and a precondition but not a
guarantee for low exposures.
5. The minimum acceptable shielding required for a syringe is 2 mm of tungsten
for 99mTc and 5 mm of tungsten for 18F . For 90Y 10 mm PMMA completely
shield beta radiation, nevertheless 5mm shielding of tungsten provides a
better shielding cutting down bremsstrahlung radiation too.
Recommendations (summary 2/2)
6. The minimum acceptable shielding required for a vial is 3mm and 3cm lead
for 99mTc and 18F respectively. For 90Y an acceptable shielding is obtained
with 10 mm PMMA with an external layer of few mm of lead.
7. Training and education on good practice (e.g. procedure planning, repeating
procedures using non radioactive sources) are more relevant parameters than
the experience of the worker.
8. All tools increasing the distance (e.g. forceps) between the hand/finger and
the source are very effective for dose reduction.
9. Working fast is not sufficient, the use of shields or increasing the distance are
more effective than pushing on the working speed.
ACKNOWLEDG
MENTS
Special thanks to all the
workers and hospitals
that have collaborated
Acknowledgment to the European
Atomic Energy Community's
Seventh Framework Programme
for funding the ORAMED project
under grant agreement n° 211361.