Practice of PET Shielding in 2000:
First We Had Chaos
PET Site Planning
and Radiation
Safety Jon A. Anderson, PhD
Department of Radiology
The University of Texas Southwestern Medical Center at Dallas
AAPM Annual Meeting, 2006
jon.anderson@utsouthwestern.edu
1
July 2006 -- AAPM Annual Meeting
Excerpts from a web discussion thread on shielding
control areas at PET facilities:
"...requirements were determined to be 1"
and 1/2" of lead..."
"...we don't have any special shielding..."
"...most do not shield the control room..."
"...this leads to lead thicknesses...of about 2 cm..."
"...we don't have any lead shielding..."
"...we have 2 mm Pb in the walls..."
"... we have ...a lead glass window ... 1/4" of lead
shielding on this wall..."
AAPM Annual Meeting, 2006
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2
What Is Different When You Have
PET or PET/CT in Your Facility?
Then We Had TG-108
1) 511 keV energy
-increases exposure rate from doses,
patients
-greatly increases thickness of required
shielding
2)Requirements for patient handling
during injection and uptake phase
3) Combined modality scanners
(PET/CT) require consideration of both
gamma-ray and x-ray hazard
Med. Phys. 33(1),January 2006
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1
The 18F-Injected Patient as a Source
(average of different investigators, 2003)
µSv/hr)/MBq
Superior 0.075 (µ
0.279 (mrem/hr)/mCi
#HVL's
all at 1 m from surface of
body, average value from
all applicable reports
Lateral
A Revealing Comparison of Lead
Requirements: X-Ray vs PET
Lead Thickness Required
mm (in)
Anterior
0.104 (µ
µSv/hr)/MBq
0.383 (mrem/hr)/mCi
0.103 (µ
µSv/hr)/MBq
0.383 (mrem/hr)/mCi
not as
anisotropic as it
might seem
0.018 (µ
µSv/hr)/MBq
Inferior 0.065 (mrem/hr)/mCi
5
30-60 min
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PET Facility Tour: University of Texas
Southwestern Medical Center at Dallas
*
Assay of dose
Radioactive
Materials
Uptake of pharmaceutical
Dock
10-60 min
Position Pt
*
Scan
QA Check of Scan
Scan
Utility
Future Camera
Office 1
Room
Reading
Room
East Corridor
Have Pt empty bladder
Release Pt
6
Receive doses
Injection of Pt
Transport Pt to scanner
10 min
jon.anderson@utsouthwestern.edu
*
* steps with
highest
technologist
exposure
Hot
Toilet
Hot Lab
Injection Scan
Room 1
#2
Injection
#1
Scan
Room 2
Control
South Corridor
Arrival of patient
5.3 (1/4)
9.9 (7/16)
19.0 (3/4)
32.5 (1 5/16)
46.0 (1 13/16)
Even a
single halfvalue layer
for PET is
an
expensive
proposition!
1. NCRP 147: Structural Shielding Design for Medical X-Ray Imaging Facilities
2. Simpkin, 2004, developed for AAPM Task Group on PET Facility Shielding
Workflow at the PET Center
(FDG Whole Body Scans)
Pt instruction and prep
0.044 (< 1/16)
0.103 (< 1/16)
0.278 (< 1/16)
0.718 (< 1/16)
1.366 (< 1/16)
1
2
4
8
10
compare this to
0.014 (µ
µSv/hr)/MBq or
0.05 (mrem/hr)/mCi
for 99mTc: factor of 8!
jon.anderson@utsouthwestern.edu
PET2
Laundry
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X-ray 1
(average primary for
rad room)
West Corridor
Storage
Read study
Break
Room
Office 3
Office 2
Patients
Business
Office
Reception &
Waiting
Print for file and referring; distribute to PACS
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8
2
Hot Lab Details: Dose Storage
alternative W
Area
transport carrier
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Notes:
1) Floor
protection
(containers
weigh > 66 lbs)
2) Space needed
depends on how
often deliveries
are made; may
have >100 mCi
here at a time,
even for one
scanner
3) Extra
shielding may
be required
9
Hot Lab Details
Hot Lab Details: Dose Assay and
Preparation Area
Notes:
1) Calibrator
convenient to
dose storage
2) L Block
close to
calibrator
3) Note use of
special PET
carrier for
syringe
4) Note L
Block: thick
window, 2"
lead, 2" lead
wrap-around
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Injection Room Details, UTSW
Notes:
1) Injection room
Hot lab
PET/CT bay
are most likely areas to
need shielding
Notes:
1) All this lead requires solid support -- have a heart-toheart talk with the cabinet maker
2) Counter mount of calibrator decreases tech exposure
3) Extra shielding required on well counter to shield
from sources in scanner, calibration sources, patient in
scanner, etc.
4) Use tungsten syringe shields for dose reduction to
fingers.
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2) To minimize
anomalous uptake
-minimize external
stimuli (false uptake!)
-keep patient quiet and
still on gurney or in
injection chair
3) Need adjacent hot
toilet for patients to use
after uptake period.
AAPM Annual Meeting, 2006
4) Indirect lighting,curtains, noise control
are desirable
jon.anderson@utsouthwestern.edu
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3
Scan Bay: PET and PET/CT Imaging
- uses rotating isotopic sources
in gantry to make attenuation
correction
- 70 % E/30% T time split
- typical 15 cm axial FOV
- 2D or 3D acquisitions
Conventional PET
- uses coupled CT scanner to
make attenuation correction
- provides auto registration of
anatomic and functional images
- faster scans through reduced
transmission image time
AAPM Annual Meeting, 2006
GE Discovery Series
Philips GEMINI
PET/CT
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Uses of adjacent spaces (including above and below) and
occupancy factors for them
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Calculation Formalism Proposed by
Task Group
B, the required barrier transmission factor, will be calculated as
B=
# patients/week
isotopes to be used, activity/pt
types of PET studies to be performed (heads, WB, cardiac)
uptake time and scan time for this equipment/study
dose delivery schedule (once a day?, multiples?); maximum
activity on hand
CT technique factors (kVp, mAs/scan [depends of # beds])
# scans per patient (additional diagnostic scans?)
amount of "non-PET" CT workload expected
jon.anderson@utsouthwestern.edu
Siemens Biograph Series
You need to
know which
one you're
getting!
Site Evaluation for PET Shielding
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Current PET/CT Implementations
15
P * d2
Γ * T * Nw * (A0 * F * t * Rt)
P = target dose in protected area (per week, hour, etc.) [µ
µSv]
d = distance to protected point [m]
Γ = dose rate constant [(µ
µSv/hr)(m2/MBq)]
T = occupancy factor (NCRP 147 or specific information)
Nw = number of patients per time period corresponding to P
A0 = initial activity (patient or point source) at start of integration time [MBq]
F = factor encompassing physical decay of the dose prior to time period
t = integration time (time the source (patient) is in the room) [hr]
Rt = "reduction factor" (accounts for decay during integration period)
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4
P: Radiation Protection Targets
N: Maximum Workload Estimation
Limitations
ALARA
per 10CFR20 Action Limit
50 mSv/yr
(5000 mrem/yr)
Pregnant worker's fetus
5 mSv/9 mo
(500 mrem/9 mo)
Members of public
(from each licensed operation)
in any hour, not to exceed
1 mSv/yr
(100 mrem/yr)
.02 mSv
(2 mrem)
1 Hour Uptake, 30 M inute Scan
5 mSv/yr
(500 mrem/yr)
16
Targets
controlled areas:
0.1 mSv/wk or
10 mrem/wk
uncontrolled areas:
0.02 mSv/wk or
2 mrem/wk
GUIDANCE: ALARA -- As Low As Reasonably Achievable
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Patient Number
Radiation workers
PET Facility Throughput Example:
This facility needs two uptake areas
13
10
Phase
7
Uptake
4
Scanning
1
8:00
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00
Time of Day
#pts/day = (Twork - Tuptake)/Tscan_rm
17
A0: Example Schedule for 18F FDG
Administered Activities for WB
will depend on which scanner you have!
Scans
Weight [kg] Weight [lb] Dose [mCi] Dose [mBq]
AAPM Annual Meeting, 2006
Doses (pre-injection) in Hot Lab
Calibration sources for scanner
330
20
740
130
286
17.5
648
110
242
15
555
90
198
12.5
462
TX Sources in scanner (PET)
70
154
10
370
CT x-ray source (for PET/CT)
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Patient (post injection, in uptake rm)
Patient (in scanner, hot toilet)
19
18
Possible Radiation Sources to
Include in the Shielding Plan
150
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# uptake areas = Tuptake/Tscan_rm
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AAPM Annual Meeting, 2006
require isotopic
workload
parameters
require CT x-ray
workload factors,
including
additional (nonPET) CT work
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5
18F:
A Plethora of Dose Rate
Constants for Point Sources (TG-108)
18F
Rate Constants
SI Units
15.5 (µ
µR/hr) m2/MBq
Air Kerma Rate
Constant
Conventional Units
Rate Constants
SI Units
Conventional Units
Exposure Rate
Constant
15.5 (µ
µR/hr) m2/MBq
0.134 (µ
µ Sv/hr) m2/MBq
0.4958 (mrem/hr) m2/mCi
Air Kerma Rate
Constant
0.134 (µ
µ Sv/hr) m2/MBq
0.4958 (mrem/hr) m2/mCi
Effective Dose
Equivalent (ANS1991)
0.143 (µ
µ Sv/hr) m2/MBq
0.5291 (mrem/hr) m2/mCi
Effective Dose
Equivalent (ANS-1991)
0.143 (µ
µ Sv/hr) m2/MBq
0.5291 (mrem/hr) m2/mCi
Tissue Dose Constant
0.148 (µ
µ Sv/hr) m2/MBq
0.5476 (mrem/hr) m2/mCi
Tissue Dose Constant
0.148 (µ
µ Sv/hr) m2/MBq
0.5476 (mrem/hr) m2/mCi
Deep Dose Equivalent
(ANS-1977)
0.183 (µ
µ Sv/hr) m2/MBq
0.6771 (mrem/hr) m2/mCi
Deep Dose Equivalent
(ANS-1977)
Maximum Dose (ANS1977)
0.188 (µ
µ Sv/hr) m2/MBq
0.6956 (mrem/hr) m2/mCi
Maximum Dose (ANS1977)
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HalfLife
[min]
Photon (511 keV)
Intensity per Decay
[%]
Positron
Energy
[MeV]
γ -Ray Dose
[(µ
µ Sv/hr)/MBq]
([(mrem/hr)/mCi])
at 1 meter
11
C 20.3
200
0.961
0.194
(0.717)
13
N 9.97
200
1.19
0.194
(0.717)
15
O 2.03
200
1.72
0.194
(0.717)
Ge 4.1e5
68
Ga (288 d)
180
1.9, 0.8
0.179
(0.662)
68
Rb 1.25
192
3.35,2.5
0.5735 (mR/hr) m2/mCi
0.6771 recommends
(mrem/hr) m2/mCi
0.183 (µ
µ Sv/hr) m2/MBqTG-108
0.143 (mSv/hr)/MBq
(mrem/hr)/mCi
0.6956
(mrem/hr) m2/mCi
0.188 (µ
µ Sv/hr) m2/MBq0.53
for F-18
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Γ: The 18F-Injected Patient as
a Source (retained activity)
Γ: Dose Rate Constants from Other
Point Source Positron Emitters
82
18F
0.5735 (mR/hr) m2/mCi
These values, from
Unger and Trubey
(ORNL/RSIC-45) are
given in µSv of deep
dose as defined in
10CFR20. (a somewhat
different measure than
the Task Group
recommended for 18F)
Dose Rate from
0.600
Dose Rate
[(µ Sv/hr)/MBq]
[(mrem/hr)/mCi]
Exposure Rate
Constant
18F: A Plethora of Dose Rate
Constants for Point Sources (TG-108)
0.500
18
F Injected Patient at 1 m
sources of variation:
delay time to measurement,
micturation status, exposure-todose conversion, etc.
TG-108 recommends
(0.092 µSv/hr)/MBq
(0.34 mrem/hr)/mCi
0.400
0.300
0.200
0.100
0.000
White 2000
Yester * 2005
(attenuation)
SI Units
0.075
0.055
0.100
0.150
0.137
0.08866
0.097
0.100
Conventional Units
0.279
0.203
0.370
0.553
0.508
0.328
0.359
0.372
Kearfott 1992
0.210
(0.778)
Chisea 1997
Cronin 1999
Benetar 2000
Massoth 2003
(unpubl.)
Average
Source
about 20% of dose will be in bladder after 1-2 hours
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6
Sources in the Gantry: Isodose
Curves from Vendor may need for
transmission or
calibration in either PET
or PET/CT!
Correction for Decay: The
Reduction Factor
Reduction Factor Rt
with line source in place
with transmission rods
extended
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0
t
0.8
0
0
0.6
0.4
0.2
0
0
20
AAPM Annual Meeting, 2006
Dose [mrem]
B=
Corrected for Physical Decay,
Self-Shielding
Corrected for Physical Decay,
Self-Shielding, Voiding
10
60
80
100
120
140
A factor of 2
= 1/8" of lead
jon.anderson@utsouthwestern.edu
Inject @ 5 minutes
Void @ 60 minutes
0
0
20
40
60
80
100
120
140
160
180
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B=
10.9 * P * d2
T * Nw * (A0 * F * t * Rt)
10.9 is 1/Γ in
[(hr/µSv)(MBq/m2)];
F=1
Image:
12.8 * P * d2
B=
T * Nw * (A0 * F * t * Rt)
12.8 includes 15%
void before imaging;
F=exp(-0.693tU/T1/2),
the physical decay
during uptake
200
Time [minutes]
AAPM Annual Meeting, 2006
200
P * d2
Γ * T * Nw * (A0 * F * t * Rt)
6
2
180
Uptake:
8
4
160
B, the required barrier transmission factor, will be calculated as
Initial Activity
Corrected for Physical Decay
40
Time [minutes]
18
12
dT
A dT
Effect of Corrections
Cumulative Dose 1 m from Patient, 10 mCi F-18
14
ln( 2)
A ⋅e
Calculation Formalism Proposed by
Task Group: Now We Have It All
Effects of Adding Corrections to
Dose Calculation
16
T
T half
0
1
Cautions: The phantoms for PET and for CT isodose curves do not
look very much like patients; the CT values may be for bare CT gantry.
AAPM Annual Meeting, 2006
−
Correction for Decay of F-18
1.2
R
with phantom in place
t
27
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7
Going from Barrier Transmission
Monte Carlo
to Shield Thickness
calculations by
Douglas
Simpkin (2004)
Lead Monte Carlo Simulation
(Broad Parallel Beam)
1.0000
Constant TVL 16.6 mm
−γ
Transmission
+
B
0.1000
x( B) :=
1
α⋅γ
⋅ ln
1+
0.0100
0.0010
0.0001
0
5
10
15
20
25
30
35
Thickness(mm)
AAPM Annual Meeting, 2006
40
45
50
β
α
β
α
Curves and fitting
parameters for iron
and concrete are
also found in the
report
jon.anderson@utsouthwestern.edu
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Example 2: How Much Shielding for a
An uncontrolled area with
Scan Room?
100% occupancy is 3m from
−6
Protection Goal:
P := 20⋅ 10
Distance:
d := 3⋅ m
Number of Patients per Week:
N := 40
Occupancy:
T := 1
1hr
6
Activity:
Source Duration:
t := 0.5hr
Reduction Factor:
R(t ) = 0.91
Gamma Constant:
Γ := .092⋅ 10
−6
(
P⋅ d
( )
⋅
T half
1
⋅ 0.85
2
the patient. 40 patients a
week are injected with 555
MBq (15 mCi) of FDG and
held elsewhere for a 1hr
uptake time. The patients
void about 15% of the dose
at 1 hr. The scan lasts 30
minutes.
2
Sv⋅ m
6
hr⋅ 10 Bq
)
xl Br = 0.807cm
Br = 0.334
( )
xc Br = 11.278 cm
AAPM Annual Meeting, 2006
P := 20⋅ 10
Distance:
d := 4⋅ m
Number of Patients per Week:
N := 40
Occupancy:
T := 1
An uncontrolled area with
100% occupancy is 4m
from the patient. 40
patients a week are injected
in this room with 555 MBq
(15 mCi) of FDG and held
for a 1hr uptake time.
Sv
6
Activity:
A 0 := 555 10 Bq
Source Duration:
t := 1hr
Reduction Factor:
R ( t) = 0.831
Gamma Constant:
Γ := .092⋅ 10
−6
2
⋅
Sv⋅ m
6
hr⋅ 10 Bq
Br :=
(
P⋅ d
2
N⋅ T⋅ A 0⋅ R( t ) ⋅ t ⋅ Γ
( )
How much shielding is
needed?
Br = 0.188
)
xl Br = 1.184 cm
( )
xc Br = 15.165 cm
AAPM Annual Meeting, 2006
Ans: 1.2 cm of Pb or 15.2
cm of concrete
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A Shielding Paradigm for Mixed
PET/CT Applications (Just a personal opinion)
1) Identify magnitude and location (x,y) of all sources,
including CT. Integrate over appropriate decay period
that source is in location. Express as dose/wk or dose/hr
at one meter, given workload.
2) Identify all barriers that will contribute to shielding,
including pigs, shipping containers, etc.
How much shielding ?
2
N⋅ T⋅ A 0⋅ R( t) ⋅ t⋅ Γ
−6
Protection Goal:
Sv
A 0 := 555⋅ 10 ⋅ Bq ⋅
Br :=
Example 1: How Much Shielding for
an Uptake Room?
Ans: 0.8 cm of Pb or 11.3
cm of concrete
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3) Establish test points (x,y) at perimeter, sensitive
locations. Identify which barriers will shield each point.
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8
A Shielding Paradigm (cont)
Example Spreadsheet
3) Calculate doses (summed over all sources, including
CT) without attenuation.
4) Start adding lead or concrete as necessary to the
barriers, recalculating the doses as you go.
5) Stop when you have met goals (100 mrem/yr, 2
mrem/hr)
jon.anderson@utsouthwestern.edu
be exposed to more than 100 mrem/yr
Sx
-14.4
-4.43
-17.6
-17.6
-15.9
-8.83
-18.7
-17.8
-22.8
-5.04
source
definitions
Sy
10.49
8.6
7.77
8.81
8.58
9.88
11
11
6.56
9.11
Total Target
mR/wkmR/wk
Loc_ID Occupancy Status Area
1
1 OK control
12.66
2
1 OK control
9.05
3
0.25 OK hot lab
7.61
4
1 OK reading room
3.62
5
1 OK reading room
2.03
6
1 OK reading room
2.44
7
1 OK E wall
1.97
8
1 OK E wall
1.81
9
1 OK E wall
1.97
10
1 OK E wall
1.97
11
1 OK E wall
1.74
12
1 OK E wall
1.70
13
1 OK E wall
1.56
14
1 OK E wall
1.41
15
1 OK E wall
1.28
16
1 OK E wall
1.14
17
1 OK E wall
1.13
100
100
100
100
100
100
2
2
2
2
2
2
2
2
2
2
2
test point
results
A spreadsheet can do all of this (including corrections for anisotropic sources).
Special purpose programs can be developed to do the same.
Pencil and paper can be used, but it is tedious!
AAPM Annual Meeting, 2006
Verification that no member of the public will
avg per hour
Input Data
Source XRate@1m
1 scan1
3.15
2 scan2
2.6
3 inj 1
3.8
4 inj 2
3.8
5 phan 1
1.1
6 phan 2
1.1
7 lab
54
8 hot_ws
0.13
9 bath
0.45
10 CT
NPETSources
9
PathID
1
2
3
4
33
Grid Calculation: No Shielding
XConst
Source Area
3.15 scan1 control
2.60 scan2 control
3.80 inj 1
control
3.80 inj 2
control
511 Calculation
Matl
Mu/Rho Rho
Mu
Concrete
0.0877
1.84 0.1614
Lead
0.161
11.34 1.8257
Lead tranmissions for CT Calc (NCRP49)
d[cm]
B
0
1
0.159 2.63E-03
0.3180 5.47E-05
0.4760 1.09E-06
0.6350 1.00E-06
shielding
material
definitions
Tot/Targ
Ratio
0.12664
0.09049
0.0761
0.03618
0.02026
0.02444
0.98403
0.90567
0.98286
0.98251
0.86885
0.85039
0.77788
0.70582
0.64054
0.57104
0.56277
Tx
-10.83
-9.60
-17.84
-12.80
-10.99
-9.60
-20.12
-18.29
-16.46
-14.63
-12.80
-10.97
-9.14
-7.32
-5.49
-3.66
-1.83
Ty
10.06
8.23
11.52
15.55
17.36
15.55
18.29
18.29
18.29
18.29
18.29
18.29
18.29
18.29
18.29
18.29
18.29
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
0
0
0
0
2.54
3.105
2.54
0
0.159
0.159
0.636
0.636
0.636
0.159
0.318
0.636
0
0
0
0
0
0
0
0
0
0
0
90
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1.571
B7
B8
barrier
definitions
B4
CT Calculation
CT Angle
320 degrees
CT mAs/hr 40000 mAs
Exposure Tolerance:
Barrier# Thick Orient q[rad] n
[cm]
B2
B3
Loc_IDOccupancy Length θ[rad]
TotReqL,WTotL, NS
d(concreted(lead)B1
1
1 3.57595 3.021053
1.02
1.12
0 0.16
1
1
1 6.56442 6.058898
0.92
1.02
0 0.163
2
1
1 7.12787 3.468667
0.66
1.23
0 0.84
5
1
1
1 6.86477 3.324703
0.68
1.23
0 0.809
4
1
AAPM Annual Meeting, 2006
Buildup Factor Coefficients
B2
B1
B0
0.049 0.473 0.994
-0.01 0.198 1.05
B5
B6
1
Comment
1
1
4
4
4
1
2
4
L-Block
PET-Net shipping case + local shield
1" lead storage case
no barriers counted
n control
s control
s hot lab
s inj 2
s inj 1
n inj area
s scan 2
e hot lab
barriers for each
test point
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Grid Calculation: Shielded
Office/Lab
Inj
C Scan
T H
Corridor
Reading
Office/Lab
Corridor
Lobby
Elevator
Elevator
Reading
Y image
Ratio of calculated dose to target dose,
adjusted for occupancy
DoseToTargetRatio
DoseToTargetRatio
Sources: Injection room, HL, HWC, Scanner, CT, Cal Source
4 pts/day, 1 hr in uptake, 2 hrs in scan room
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No shielding in walls in excess of 5/16" Pb
AAPM Annual Meeting, 2006
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9
A Suggested Design Philosophy
Look Up, Down, and Sideways
Electrical
Electrical
Corridor
Elevator,
Lobby
Corridor
Mechanical Space
Mechanical Space
Glass Wash
Exterior
Floor Plan
AAPM Annual Meeting, 2006
-Keep the hot areas in interior of space, away from
adjacent, uncontrolled occupancies to reduce shielding
requirement
Relative Dose Map on Floor Above
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Where to Put the Lead:
Shadow vs Complete Coverage
-Alternatively, place the hot areas against exterior
walls adjacent to very low occupancy spaces (exterior
landscaping, etc.); may need to control area (fence)
-Be prepared to use both inclusive (lead-lined or
concrete walls) and spot (shadow) shielding in order to
meet protection goals and to minimize lead
requirements.
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Examples of Shadow Shields
Alternatives:
Complete coverage -- like most x-ray shielding
-contractors are familiar with technique
-facility previously shown had lead thicknesses
of 1.6 mm to 6.3 mm, easily managed
- makes sense for PET/CT where CT must be
shielded
Shadow shielding -- big slabs next to trouble spots
-can reduce overall cost when thick shield needed
- provides flexibility when remodeling old work
AAPM Annual Meeting, 2006
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from JA Anderson, RJ Massoth,
and LL Windedahl, 2003 AAPM
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10
Magnitude of Technologist
Consistent with conventional nuclear medicine
Exposure
practice, most of technologist dose comes from
positioning, transport, and injection.
More on Technologist Exposure
1) It is often seen that the technologist dose per mBq handled
drops as a function of experience in the PET clinic.
Dose/Activity Handled
µ Sv/MBq
(mrem/mCi)
Technologist Doses
A 2004 update to the previous UTSW data for the same two
technologists as shown on preceding slide showed a normalized
WB dose of 0.011 µSv/MBq (0.041 mrem/mCi), down by 40%
since 2002.
average dose/procedure
< 10 µSv (1 mrem)
0.150
0.100
0.050
0.000
Chisea
McElroy
UTSW
Roberts
Guillet
Biran
Yester Average
SI Units
0.018
0.012
0.023
0.019
0.019
0.011
0.009
0.029
0.021
0.018
Conventional Units
Benetar Chisea
0.067
0.044
0.085
0.069
0.069
0.041
0.032
0.107
0.077
0.066
Reference
AAPM Annual Meeting, 2006
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Operating Suggestions to Minimize
Technologist Dose
Lay out hot lab to minimize handling time. Use unit doses.
Complete patient instruction, interaction before injection.
Minimize time near patient after injection.
Establish IV access with butterfly infusion set before injection.
Use other personnel for patient transport.
Shield control area to reduce dose during scan.
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jon.anderson@utsouthwestern.edu
Acknowledgements
Use syringe shields, syringe carriers, carts, etc. to reduce
exposure during dose transport, injection.
AAPM Annual Meeting, 2006
2) Assuming an average dose of 0.018 µSv/MBq injected, 8
pt/day and 370 MBq (10 mCi) injected/pt, this would yield a
yearly dose of 13.3 mSv (1330 mrem), within regulation but
above usual ALARA investigational limits. Over nine months,
it would be 10.4 mSv (1040 mrem), well above the declared
pregnancy limit.
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•
•
•
•
•
•
•
•
Tammy Pritchett, RT, CNMT
Michael Viguet, CNMT
Dana Mathews, MD
Thomas Lane, PhD
Richard Massoth, PhD
Larry Windedahl
Doug Simpkin, PhD
Mark Madsen, PhD
AAPM Annual Meeting, 2006
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11
The
End
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