PET/CT Facility
Design
2010
American College of Medical
Physics
Jon A. Anderson, PhD
Department of Radiology
ACMP,
2010
jon.anderson@utsouthwestern.edu
1
The
University
of Texas Southwestern
Medical Center at Dallas
What Is Different When You Have
PET/CT in
i Your
Y
Facility?
F ilit ?
1) 511 keV energy
-increases
increases exposure rate from doses,
patients
-greatly increases thickness of required
shielding
hi ldi compared
d tto di
diagnostic
ti rooms
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 hazards
4) You can affect neighboring modalities
ACMP, 2010
jon.anderson@utsouthwestern.edu
2
The 18F-Injected Patient as a Source
(average off diff
different investigators,
i
i
2003)
Superior 0.075 (Sv/hr)/MBq
0.279 (mrem/hr)/mCi
L t l
Lateral
Anterior
0.104 (Sv/hr)/MBq
0.383 (mrem/hr)/mCi
0.103 (Sv/hr)/MBq
0.383 (mrem/hr)/mCi
not as
anisotropic as it
might seem
I f i
Inferior
ACMP, 2010
all at 1 m from surface of
body average value from
body,
several investigators
0.018 (
(Sv/hr)/MBq
)
q
0.065 (mrem/hr)/mCi
compare this to
0 014 (Sv/hr)/MBq
0.014
( S /h )/MB or
0.05 (mrem/hr)/mCi
for 99mTc.
Tc 18F values
factor of 8 larger!
jon.anderson@utsouthwestern.edu
3
A Revealing Comparison of Lead
R
Requirements:
i
t X
X-Ray
R vs PET
# Half
V l
Value
Layers
Lead Thickness Required
mm (inches,
(i h to
t nextt 1/16)
X-ray
y1
(Average primary
spectrum for rad room)
PET2
00.044
044 (< 1/16
1/16”))
0.103 (< 1/16”)
0.278 ((< 1/16”))
0.718 (< 1/16”)
1.366 (< 1/16”)
55.3
3 (1/4
(1/4”))
9.9 (7/16”)
19.0 ((3/4”))
32.5 (1 5/16”)
46.0 (1 13/16”)
1
2
4
8
10
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
ACMP, 2010
jon.anderson@utsouthwestern.edu
4
A Revealing
Comparison
of
Lead
Bottom Line: for DX shielding, we find that
theR
answer,
some to
R 1/16"i lead is (usually)
Requirements:
t X
X-Ray
vswith
PET
spare. We Lead
usually
make very
conservative
#HVL's
Thickness
Required
calculations mm
calculations,
because
are cheap.
cheap
(i to
(in,
t HVL’s
nextt 1/16)
Even a
X-ray 1
PET2
Not true(average
in PET.
As for
we will see, normally
we halfprimary
single
rad room)
need 1-4 HVL's
of shielding (1/4”-3/4”!). We tend
1.
2.
value layer
1 put just
0.044
(< we
1/16)
5.3to
(1/4)
to
what
need, due
$$$. for PET is
2
0.103 (< 1/16)
9.9 (7/16)
an expensive
Implication:
every protection
we need
4
0.278 At
(< 1/16)
19.0 (3/4)point, proposition!
t8 include
to
i l d 0.718
all
ll sources
th t32.5
can(1be
b 5/16)
contributing
t ib ti to
t
(< 1/16) that
the
that(<point
multiple
injection
10 dose at
1.366
1/16) (i.e.46.0
(1 13/16)
rooms scan rooms,
rooms,
rooms CT contributions,etc.),
contributions etc ) and
NCRP 147: Structural Shielding Design for Medical X-Ray Imaging Facilities
Simpkin,
for AAPM estimate
Task Group on
Facility
Shielding
make2004,
thedeveloped
best possible
toPET
save
$$$.
ACMP, 2010
jon.anderson@utsouthwestern.edu
5
Workflow at the PET Center
(FDG Whole Body Scans)
Arrival of patient
Receive doses
Injection of Pt
Pt instruction and prep
30-90 min
*
Assay of dose
Uptake of pharmaceutical
55-20
20 mCi
Have Pt empty bladder
Transport Pt to scanner
5-10 min
Position Pt
5-20 min
Scan
Release Pt
*
*
*
QA Check of Scan
* steps with
highest
technologist
exposure
Read study
Distribute to PACS or Media
ACMP, 2010
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6
*
Magnitude of Technologist
Consistent with conventional nuclear
E
Exposure
medicine practice, most of technologist
dose comes from positioning, transport,
and injection.
j
Dos
se/Activity
y Handled
d
MBq
 Sv/M
(mrem/mCi)
Technologist Doses
average dose/procedure
< 10 Sv (1 mrem)
0 150
0.150
0.100
0.050
0.000
Benetar Chisea
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
0.067
0.044
0.085
0.069
0.069
0.041
0.032
0.107
0.077
0.066
Reference
ACMP, 2010
jon.anderson@utsouthwestern.edu
7
More on Technologist Exposure
1) Individual technologist dose should drop as
experience
p
increases
Over a two year period with the same technologists, we saw a 40%
d
decrease
iin radiation
di ti d
dose per unit
it activity
ti it handled.
h dl d
2) For
0.018 Sv/(MBq injected)
370 MBq (10 mCi) injected/pt
10 pt/day
Yearly:
9 Months:
16.6 mSv (1660 mrem) (<5 rem, >ALARA trigger)
12.5 mSv (1250 mrem) (> declared pregnancy limit)
ACMP, 2010
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8
Operating Suggestions to Minimize
T h l i t Dose
Technologist
D
Minimize handlingg time. Use unit doses.
Use tungsten syringe shields, employ syringe carriers,
transport carts, etc. to minimize
i i i handling
h dli exposure.
Instruct patient before injection
injection. Minimize contact
afterward.
Establish IV access with butterfly infusion set.
Use other personnel for hot patient transport.
ACMP, 2010
jon.anderson@utsouthwestern.edu
9
Radioactive
Materials
Dock
L
Laundry
PET Facility Tour: University of Texas
Southwestern Medical Center at Dallas
Strip shopping center, uncontrolled
(2001-2007)
occupancies on both sides
Scan
Utility
Future Camera
Office 1
Room
Reading
Room
Hot
Toilet
Hot Lab
Injection Scan
Room 1
#2
Injection
#1
Scan
S
Room 2
Control
South Corriidor
East Corridor
ACMP, 2010
Break
Room
Offi 2
Office
Patients
West Corridor
Storage
Office 3
Business
Office
Reception &
Waiting
jon.anderson@utsouthwestern.edu
10
Radioactive
Materials
Dock
Laundry
PET Facility Tour: University of Texas
Southwestern Medical Center at Dallas
(2001-2007)
Scan
Utility
Reading
Room
Future Camera
Office 1
Room
South Co
orridor
East Corridor
If you can get involved
in the
Hot Lab planning, you can save
Office 3
architectural
Scan
Scan
Injection
R
2 instead
R using
Room
1 i
#2
some money,
by
distance
i Room
i
Hot
Control
Injection
Toilet
of lead. #1
West Corridor
Storage
ACMP, 2010
Break
Room
Office 2
Patients
Business
Office
Reception &
Waiting
jon.anderson@utsouthwestern.edu
11
Hot Lab Details: Dose Storage
Area
Notes:
1) Floor
protection
(containers
weigh
eigh > 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
ACMP, 2010
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12
Hot Lab Details: Dose Assay and
P
Preparation
ti Area
A
Notes:
1)) Calibrator
convenient to
dose storage
2) L Block
close to
calibrator
3) Note use of
special
i PET
carrier for
syringe
4) Note L
Block: thick
window, 2"
lead 22" lead
lead,
wrap-around
ACMP, 2010
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13
Hot Lab Details
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) U
Use ttungsten
t syringe
i
shields
hi ld ffor d
dose reduction
d ti tto
fingers.
ACMP, 2010
jon.anderson@utsouthwestern.edu
14
Injection Room Details
Notes:
1) Injection room
Hot lab
PET/CT b
bay
are most likely areas to
need shielding
2) To minimize
anomalous uptake
-minimize
minimize external
stimuli (false uptake!)
-keep patient quiet and
still on ggurney
y or in
injection chair
3) Need adjacent hot
toilet for patients to use
after uptake period.
ACMP, 2010
4) Indirect lighting,curtains, noise control
are desirable
jon.anderson@utsouthwestern.edu
15
Calculation Formalism Proposed by
T kG
Task
Group 108
108: General
G
l Form
F
B, the required barrier transmission factor, will be calculated as
P * d2
B=
 * T * Nw * A0 * Ftot * t * Rt)
P = target dose in protected area (per week, hour, etc.) [Sv]
d = distance from source (patient) to protected point [m]
 = dose rate constant [(Sv/hr)(m2/MBq)]
T = occupancy factor (NCRP 147 or specific information)
Nw = number of patients per time period corresponding to P
A0 = injected activity [MBq]
Ftot = factor encompassing physical decay of the injected dose and possible
elimination from body = Fphys * Felim
t = integration time (time the source (patient) is in the room) [hr]
Rt = "reduction factor" (accounts for decay during dose integration period)
ACMP, 2010
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16
Site Evaluation for PET Shielding
Uses of adjacent spaces (including above and below) and
occupancy factors for them
# patients/week
isotopes to be used, activity/pt
t
types
off PET studies
t di to
t be
b performed
f
d (b
(brains,
i WB
WB, cardiac)
di )
uptake time and scan time for this equipment/study/center
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?)
amountt off "
"non-PET"
PET" CT workload
kl d expected
t d
ACMP, 2010
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17
Radiation Sources to Include in the
Shielding Plan
require isotopic
Doses (pre-injection) in Hot Lab
workload
parameters:
Calibration sources for scanner
pts/wk, mCi/pt
uptake,scan
t k
ti
times
Patient (post injection, in uptake rm)* isotope type and
delivery scheds
Patient (in scanner, hot toilet)
require CT x-ray
workload factors,
factors
techniques,
CT x-ray source (for PET/CT)
include non-PET
CT work
ACMP, 2010
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18
P: Radiation Protection Targets
Limitations
ALARA
per 10CFR20 Action Limit
Radiation workers
50 mSv/yr
(5000 mrem/yr)
Pregnant worker's fetus
5 mSv/9 mo
(500 mrem/9 mo)
public
Members of p
(from each licensed operation)
in any hour, not to exceed
1 mSv/yr
y
(100 mrem/yr)
.02 mSv
(2 mrem)
5 mSv/yr
(500 mrem/yr)
Targets
controlled areas:
100 Sv/wk or
10 mrem/wk
uncontrolled areas:
20 Sv/wk or
2 mrem/wk
GUIDANCE: ALARA -- As Low As Reasonably Achievable
ACMP, 2010
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19
N: Maximum Workload Estimation
PET Facility Throughput Example:
90 Minute Uptake, 30 Minute Scan
Pa
atient Number
15
13
11
15 patients/day
i
/d
three uptake rooms
9
7
Phase
5
Uptake
p
3
Scanning
1
7:00 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 = (tworkday - tuptake)/tscan_rm
ACMP, 2010
# uptake areas = tuptake/tscan_rm
jon.anderson@utsouthwestern.edu
20
18F: A Plethora of Dose Rate
Constants for Point Sources (TG-108)
18F
Rate Constants
SI Units
Conventional Units
0.5735 (mR/hr) m2/mCi
Exposure Rate
Constant
15.5 (R/hr) m2/MBq
Air Kerma Rate
C
Constant
0.134 (Sv/hr) m2/MBq
0.4958 (mrem/hr) m2/mCi
Effective Dose
Equivalent (ANS-1991)
0.143 (Sv/hr) m2/MBq
0.5291 (mrem/hr) m2/mCi
Tissue Dose Constant
0.148 (Sv/hr) m2/MBq
0.5476 (mrem/hr) m2/mCi
Deep Dose Equivalent
(ANS-1977)
0.183 (Sv/hr) m2/MBq
Maximum Dose (ANS1977)
0.188
ACMP, 2010
0.6771recommends
(mrem/hr) m /mCi
TG-108
0.143 (Sv/hr)/MBq
(Sv/hr) m /MBq 0.6956 (mrem/hr) m /mCi
0.53 (mrem/hr)/mCi
for F-18 bare source
2
jon.anderson@utsouthwestern.edu
2
2
21
: The 18F-Injected Patient as
a Source (retained activity)
Dose Rate from
D
Dose
Ra
ate
[(  Sv/hr)/M
MBq]
[(mrrem/hr)//mCi]
0.600
0.500
18
F Injected Patient at 1 m
sources off variation:
i ti
delay time to measurement,
micturation status, exposure-todose conversion, etc.
TG-108
TG
108 recommends
d
(0.092 Sv/hr)/MBq
(0.34 mrem/hr)/mCi
0.400
0.300
0.200
0.100
0.000
Kearfott 1992
Chisea 1997
Cronin 1999
Benetar 2000
White 2000
Yester * 2005
( tt
(attenuation)
ti )
Massoth 2003
(
(unpubl.)
bl )
Average
g
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
Source
about 20% of dose will be in bladder after 1-2 hours;TG108 uses 15%
ACMP, 2010
jon.anderson@utsouthwestern.edu
22
Effects of Adding Corrections to
Dose Calculation
Effect of Corrections
Cumulative Dose 1 m from Patient, 370 MBq F-18, 60 Minute Uptake
120
Uncorrected
Dose [mic
croSv]
100
A factor of 2 =
1/4" of lead
Corrected for Physical Decay
80
Corrected for Physical Decay, SelfShielding
C
Corrected
t d ffor Ph
Physical
i l Decay,
D
SelfS lf
Shielding, Voiding
60
40
Inject @ 5 minutes
Void @ 65 minutes
20
0
0
20
40
60
80
100
120
Time [minutes]
ACMP, 2010
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23
Going from Barrier Transmission
M t C
Monte
Carlo
l
to Shield Thickness (PET) calculations by
Douglas
Simpkin (2004)
Lead
Monte Carlo Simulation
(Broad Parallel Beam)
1.0000
  B     



1


x( B) 
 ln 

 

1




Constant TVL 16.6
16 6 mm
Transm
mission
0.1000
0.0100
0.0010
0.0001
0
5
10
15
20
25
30
Thickness(mm)
ACMP, 2010
35
40
45
50
Curves and fitting
parameters for
f iron
i
and concrete are
also found in the
TG 108 report
jon.anderson@utsouthwestern.edu
24
Example 1: Uptake Room
6
Protec tion Goal:
P  20 10
Dis tance:
d  4 m
Sv
6
Gamma Cons tant:
  .092
092 10
Oc cupancy:
T  1
Number of Patients per W eek:
Nw  40
Injected Ac tivity:
A 0  555  10 Bq
Decay/Elimination:
F  1
Sourc e D uration:
t  1hr
Reduc tion Fac tor:
R( t)  0.831
0 831
How much shielding?
Br  0.188
Ans: 1.2 cm of Pb or 15.2
cm of concrete
Br 

2
Sv m
An uncontrolled
A
t ll d area with
ith
100% occupancy is 4m
from the patient
patient. 40
patients a week are
injected
j
in this room with
555 MBq (15 mCi) of
FDG and held for a 1hr
uptake time.
6
hr 10 Bq
6
P d
2

  T Nw A 0 F R( t)  t
 

xPb Br  1.184cm
ACMP, 2010
 
xconc Br  15.165cm
jon.anderson@utsouthwestern.edu
25
Example 2: Scan Room
6
P t tion
Protec
ti Goal:
G l
P  20 10
Dis tance:
d  3 m
Sv
6
2
G
Gamma
Cons
C
ttant:
t
  .092
092 10
Oc cupancy:
T  1
N b off P
Number
Patients
ti t per W eek:
k
Nw  40
Injected Ac tivity:
A 0  555  10 Bq
6
hr 10 Bq
6

  ln( 2) 
Decay/Elimination:
F  e 
Sourc e D uration:
t  0.5hr
Reduc tion Fac tor:
R( t)  0.91
Br 

Sv m
P d
( 1hr) 
T half 
  ( 1  15%)
An uncontrolled area with
100% occupancy is 3m
from the scan bay.
bay 40
pts/week, 555 MBq (15
mCi)
C ) FDG/pt,
G/pt, 1hr uptake
upta e
time. Patients void (15%
of the dose) at 1 hr. 30
minutes spent in scan bay.
How much shielding ?
2

  T Nw A 0 F R( t)  t
 

xPb Br  0.807cm
ACMP, 2010
Br  0.334
 
xconc Br  11.278cm
Ans: 0.8 cm of Pb or 11.3
cm of concrete
jon.anderson@utsouthwestern.edu
26
A Shielding Paradigm for PET/CT
(A personal opinion)
A li ti
Applications
0) Use architectural layout to minimize shielding
requirements (use distance, low occupancies)
1) Identify magnitude and location of sources
sources, including
CT. Integrate over period that source is in place, giving
dose/wk or dose/hr at one meter for given workload.
2) Identify all barriers that will contribute to shielding,
including pigs, shipping containers, etc. Establish test
points at perimeter, sensitive locations. Identify which
b i
barriers
will
ill shield
hi ld each
h point.
i t
ACMP, 2010
jon.anderson@utsouthwestern.edu
27
A Shielding Paradigm (cont)
3) Calculate doses (both CT and PET) without
attenuation.
4) Start adding lead or concrete as necessary to the
barriers, recalculating the doses (CT and PET) as you
go. Spread the lead and you may not have to hang
reall thick sheets!
really
5) Stop when you have met goals (1 mSv/yr, 20 Sv/hr)
A spreadsheet can do all of this (including corrections for anisotropic sources).
S i l purpose programs can be
Special
b d
developed
l
d tto d
do th
the same.
Pencil and paper can be used, but it is tedious!
ACMP, 2010
jon.anderson@utsouthwestern.edu
28
Example Spreadsheet
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
38
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
be exposed to more than 100 mrem/yr
Sx
-14.4
-4.43
-17.6
-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
8.81
8.58
9.88
11
11
6.56
9.11
Total Target
Tot/Targ
Ratio
Loc_ID Occupancy Status Area
mR/wkmR/wk
1
1 OK control
12.66
100 0.12664
2
1 OK control
9.05
100 0.09049
3
0.25 OK hot lab
7.61
100 0.0761
4
1 OK reading room 3.62
100 0.03618
5
1 OK reading room 2.03
2 03
100 0.02026
0 02026
6
1 OK reading room 2.44
100 0.02444
7
1 OK E wall
1.97
2 0.98403
8
1 OK E wall
1.81
2 0.90567
9
1 OK E wall
1.97
2 0.98286
10
1 OK E wall
1.97
2 0.98251
11
1 OK E wall
1.74
2 0.86885
12
1 OK E wall
1.70
2 0.85039
13
1 OK E wall
1.56
2 0.77788
14
1 OK E wall
1.41
2 0.70582
15
1 OK E wall
1.28
2 0.64054
16
1 OK E wall
1.14
2 0.57104
17
1 OK E wall
1.13
2 0.56277
test point
results
PathID
XConst
1
2
3
4
3.15
2.60
3.80
3.80
Source
scan1
scan2
inj 1
inj 2
Area
control
control
control
control
ACMP, 2010
Loc_IDOccupancy
1
1
1
1
1
1
1
1
Length
3.57595
6.56442
7.12787
6.86477
511 Calculation
Matl
Mu/Rho Rho
Mu
Concrete
0.0877
1.84 0.1614
Lead
0 161
0.161
11 34 1.8257
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
Tx
-10.83
-9.60
-17.84
-12.80
-10.99
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
-7
-6
-5
-4
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
B2
1
2
5
4
B3
B4
CT Calculation
CT Angle
320 degrees
CT mAs/hr 40000 mAs
Exposure Tolerance:
Barrier# Thick Orient q[rad] n
[cm]
Ty
10.06
8.23
11.52
15.55
17 36
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
TotReqL,WTotL, NS
d(concret d(lead)B1
rad
3.021053
1.02
1.12
0 0.16
6.058898
0.92
1.02
0 0.163
3.468667
0.66
1.23
0 0.84
3.324703
0.68
1.23
0 0.809
Buildup Factor Coefficients
B2
B1
B0
0.049 0.473 0.994
-0.01
0 01 0.198
0 198 1.05
1 05
B5
B6
1
1
jon.anderson@utsouthwestern.edu
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
29
Grid Calculation: No Shielding
Office/Lab
O
ce/ ab
Inj
S
C Scan
T H
Office//Lab
Reading
Corrridor
Corridor
Eleevator
Loobby
Eleevator
Reaading
Ratio of calculated dose to target dose,
DoseToTargetRatio
adjusted for occupancy
Sources:
So
rces: Injection room,
room HL,
HL HWC,
HWC Scanner,
Scanner CT
CT, Cal So
Source
rce
4 pts/day, 1 hr in uptake, 2 hrs in scan room
ACMP, 2010
jon.anderson@utsouthwestern.edu
30
Grid Calculation: Shielded
Y image
DoseToTargetRatio
No shielding in walls in excess of 5/16"
5/16 Pb; did require ceiling, floor
shielding. Was not necessary to run "box" to ceiling.
ACMP, 2010
jon.anderson@utsouthwestern.edu
31
Grid Calculation: No Shielding
Office//Lab
Corrridor
OOPS's happen with complicated
Office/Lab
O
ce/
ab
schemes:
Both floor and ceiling
needed lead, installed as lead sheet
Corridor
bonded
to p
plywood
y
p
panels and held
Inj
Reading C Scan
S
in brackets
fastened to structural
T H
web, but different thickness above
and
db
below.
l
Eleevator
Loobby
Eleevator
Reaading
The contractor switched them in
Ratio of calculated
to target dose,
spite of explicit drawings
anddose
clearly
adjusted for occupancy
labeled leaded
panels.
p
So rces: Injection room,
Sources:
room HL,
HL HWC,
HWC Scanner,
Scanner CT
CT, Cal So
Source
rce
DoseToTargetRatio
4 pts/day, 1 hr in uptake, 2 hrs in scan room
ACMP, 2010
jon.anderson@utsouthwestern.edu
32
Example: University of Texas
S th
Southwestern
t
Medical
M di l Center
C t 2007
'HOT' TOILET
2.480A
INJECTION 1
2.480B
'HOT' LAB
2.480C
54"
54"
STORAGE
2.490
INJECTION 2 INJECTION 3 INJECTION 4
2.480D
2.480F
2.480E
'HOT' TOILET
2.480G
CLINICAL
STORES
2.480H
SCAN
UTILITY
2.592
CORRIDOR
2.5
NURSE
2.481B
CORRIDOR
2.481
FUTURE
SCANNER BAY 1
2.591A
SCANNER BAY 2
2.591B
SCANNER BAY 3
2.591C
SUB-WAITING
2.481A
PHYSICIAN 1
2.450
CORRIDOR
2.482
CONTROL/OBSERVATION
2.591
PHYSICIAN 2
2.440
FILE ROOM
2.591G
MANAGER
2 591H
2.591H
ACMP, 2010
LAB
2.591F
READING 1
2 591E
2.591E
READING 2
2 591D
2.591D
jon.anderson@utsouthwestern.edu
Overall
d i
design:
No
N
lead in excess
of 3/8". North
wall of
injection
rooms, hot lab
shielded with
16" of drylaid fulllaid,
f ll
density
concrete block
33
Look Up, Down, and Sideways
Duct penetrations in ceiling
required separate shielding.
Electrical
Electrical
Corridor
Elevator,
Lobby
Corridor
Mechanical Space
Mechaniccal Space
Glass Wash
Exterior
Floor Plan
ACMP, 2010
Relative Dose Map on Floor Above
jon.anderson@utsouthwestern.edu
34
Living With Your Neighbors:
Nuclear Medicine
Nuclear Medicine
PET/CT
No Problem
Problems!
Issues
- Sources: PET patients, scan bay, hot lab, calibration sources, CT
- Affects: Imaging, Correction Floods, Tuning, Calibration
- Considerations: Collimators, detector housing (tub) relatively
transparent to 5ll keV
ACMP, 2010
jon.anderson@utsouthwestern.edu
35
Living With Nuclear Medicine
(anecdotal results)
Nuclear Medicine
PET/CT
10 mCi F18 @ 15 ft
Problems?
N shielding
No
hi ldi
LEHR, 2 mCi Tc99m
i FOV,
in
FOV llocalized,
li d
6 kcps to image
ACMP, 2010
Presents perhaps 1-3 kcps
(back or face of detector),
but more-or-less
uniformlyy distributed
jon.anderson@utsouthwestern.edu
36
Living With Nuclear Medicine
Advice is Hard to Come By
One vendor suggests that 25’
25 is an adequate separation of their
nuclear cameras from the patient couch of a PET scanner (patient
has cooled off at this point!).
Conversations with technical staff and field engineers indicate that
there are more severe pproblems when pperformingg calibrations,, high
g
count floods, or head tunes on NM equipment. Again, one source
indicates “Our experience has been that it is virtually impossible to
put sufficient shielding in the walls to reduce the exposure low
enough to be able to do intrinsic calibrations when FDG imaging
is being done in the adjoining room. …intrinsic calibrations are
not possible
bl when
h a CT is being
b
usedd in an adjoining
d
room.”
”
ACMP, 2010
jon.anderson@utsouthwestern.edu
37
Living With Nuclear Medicine
Closing Thoughts
S
Separate
t Nuclear
N l
Medicine
M di i andd PET as widely
id l as possible.
ibl
NM imaging will be less affected than NM calibrations.
Shielding may be required, but we have no standards right now. It
may be advantageous to extend the CT shielding above the normal
7’ level.
It may be
b necessary to
t schedule
h d l some types
t
off NM service
i (intrinsic
(i t i i
calibrations, tunes, high count floods) at times when there will be
no CT operations and no PET isotopes (patients, unshielded
sources) in adjacent areas.
ACMP, 2010
jon.anderson@utsouthwestern.edu
38
The
End
ACMP, 2010
jon.anderson@utsouthwestern.edu
39