LBT Radiation Physics Consulting Ltd Phillip W Patton, PhD CHP DABR DABSNM

Above Group Inc

305 East Drive Suite H

Melbourne, Florida 32904

Shielding Evaluation of New PET/CT Room & Uptake Rooms

VAMC – Bay Pines

10000 Bay Pines Blvd

Bay Pines, Florida 33744

April 21, 2025

Updated July 24, 2025

LBT Radiation Physics Consulting, Ltd.

2608 Morning Cloud Lane

Las Vegas, NV 89142

702-336-3004

Phillip W Patton, PhD, CHP, DABR DABSNM

Diagnostic Medical Physicist

This report is to document the shielding required for new PET/CT and uptake rooms going in

VAMC- Bay Pines. The calculations were conducted assuming the facility will treat 39 patients per week with an activity of 13 mCi F-18 in the PET/CT room. The forty patients were divided into 3 uptakes rooms The shielding calculations were performed using NCRP 147. The hallways between the control room, uptake room, and scan room were considered controlled rooms. The distance from the rooms on the second floor to the third floor is 19.5 feet. The distance from the floor below these rooms to the current floor is 23 feet. There is slightly more than 6 inches of concrete as support between these rooms and the rooms above.

Figure 1: PET/CT, and Uptake Rooms Layout

Summary of Shielding Requirements Barrier Type Recommended Shielding

PET/CT SCAN ROOM

A-B (Control Room Wall & Door) Restricted Recommend 1/16” lead shielding.

B-C (Corridor Wall) Unrestricted Recommend 1/16” lead shielding.

C-D (Corridor Wall) Unrestricted Recommend 1/16” lead shielding.

D-A (Corridor Wall) Unrestricted Recommend 1/16” lead shielding.

Floor Unrestricted No additional shielding required.

Ceiling Unrestricted No additional shielding required.

UPTAKE ROOM 2C120

E-F (Corridor Wall & Door) Unrestricted Recommend 1/8” lead shielding.

G-H (Uptake Room 2C121B) Unrestricted Recommend 1/8” lead shielding.

F-G (Outside Wall) Unrestricted No additional shielding required.

E-H (Corridor Wall & Door) Unrestricted Recommend 1/8” lead shielding.

UPTAKE ROOM 2C121B

H-I (Corridor Wall & Door) Unrestricted Recommend 1/8” lead shielding.

G-H (Uptake Room 2C120) Unrestricted See G-H in Uptake 2C120.

G-J (Outside Wall) Unrestricted No additional shielding required.

I-J (Uptake Room 2C121A) Unrestricted Recommend 1/8” lead shielding.

UPTAKE ROOM 2C121A

I-J (Uptake Room 2C121B) Unrestricted See I-J in Uptake 2C121B.

I-L (Corridor Wall & Door) Unrestricted Recommend 1/8” lead shielding.

K-L (Hot Lab) Unrestricted Recommend 1/8” lead shielding.

J-K (Outside Wall) Unrestricted No additional shielding required.

Hot Toilet 2C124A

M-N (Hot Lab) Restricted Recommend 1/16” lead shielding.

M-P (Corridor Wall & Door) Unrestricted Recommend 1/16” lead shielding.

P-O (Thyroid Room Wall) Unrestricted Recommend 1/16” lead shielding.

N-O (Outside Wall) Unrestricted No additional shielding required.

Hot Toilet 2C122D

Q-R (Open Space/Control Room) Restricted No additional shielding required.

R-S (Consultation Room Wall) Unrestricted Recommend 1/16” lead shielding.

S-T (Corridor Wall) Unrestricted Recommend 1/16” lead shielding.

T-Q (Corridor Wall & Door) Unrestricted Recommend 1/16” lead shielding.

In general, calculated shielding is often overestimated due to assumptions on workload, use factors, and occupancy factors. I have attempted to provide more realistic factors based on information from the facility and modified occupancy estimates.

For the PET/CT room, calculations were made using a one (1) hour uptake and a half (1/2) hour scan time. Calculations are on Page 5.

For the Hot Lab it is recommended to shield the sources and the cabinets as is common practice. Therefore, no additional shielding will be needed. If you want to add shielding, 1/16” will help reduce the rare times the sources are not behind an L shield or in a shielded drawer.

For the uptake, the patient is assumed to be located in the center of the room toward the outside wall unless otherwise noted on the diagram. This will allow for the best protection to the population outside of the nuclear medicine area. The patient is assumed to be seated and alone during the hour of uptake. Calculations are on Page 5.

All lead sheeting should extend to a height of at least 7 feet above floor level. Nail heads do not need to be overlapped. Doors and windows require the same amount of lead or lead equivalent shielding as the wall it is part of. Additionally, any outlets or cutouts in the walls will need the same shielding as the wall placed behind the outlet or cutout. Overlying drywall seams should be offset and great care should be exercised in taping and plastering seams. No gaps in drywall are acceptable. If you have any questions, please contact me at (702) 336-3004.

Sincerely Yours, Phillip W Patton, PhD DABR CHP DABSNM

Diagnostic Medical Physicist

LBT Radiation Physics Consulting

References

(1) National Council on Radiation Protection and Measurements (NCRP) Report 147, Structural Shielding Design for Medical X-ray Imaging Facilities, NCRP, 2004

(2) Madsen, M.T., Anderson, J.A., Halama, J.R., Kleck, J., Simpkin, D.J., Votaw, J.R., Wendt, R.E., III, Williams, L.E. and Yester, M.V. (2006), AAPM Task Group 108: PET and

PET/CT Shielding Requirements. Med. Phys., 33: 4-15. https://doi.org/10.1118/1.2135911 https://doi.org/10.1118/1.2135911

Calculations

CT Component of PET/CT Room

PET Component of PET/CT Room

Shielding requirements:

Design Dose

(mrem/wk) T

P/T

(mrem/wk) Dist (ft)

Unshielded

Dose

(mrem/wk)

Required

Transmiss

Required Pb

(mm)

Required Pb

(inches)

Required

Concrete

(mm)

Required

Concrete

(inches)

10 1.000 10 13.0 477.4 0.02094 0.908 1/28 100.1 3.94

2 0.200 10 10.0 806.9 0.01239 1.093 1/23 115.0 4.53

2 0.200 10 13.0 477.4 0.02094 0.908 1/28 100.1 3.94

2 0.025 80 10.0 806.9 0.09915 0.439 1/58 57.0 2.24

2 1.000 2 19.0 1.2 1.67776 None None -10.9 -0.43

2 0.200 10 22.0 0.9 11.24703 None None -42.6 -1.68

Floor/ceiling too thin: Determine how much Pb to add. OK

HVL in lead= 0.1 mm Pb , HVL in concrete= 1.5 cm concrete per NCRP 49, 150 kVp.

Present floor/ceiling consists of 4.5 inches concrete= 11.43 cm conc= 7.6 HVLs thick

Required ceiling transmission= 1.67776 or -0.7 HVLs, so must add -8.4 HVLs. This is -0.84 mm Pb to add.

Required floor transmission= 11.24703 or NA HVLs, so must add NA HVLs. This is NA mm Pb to add.

Floor (Corridor & Open Space)

Ceiling (Office)

Barrier

AB Control Room

BC Corridor

CD Corridor

DA Corridor

Patient Dose

Rate Constant

(uSv-m /MBq-h)

Dose Rate

Constant (uSv-m /MBq-h)

Dose Reduction

Factor over time

Uptake

Dose Reduction

Factor over time

Imaging

FDG 0.092 0.143 0.83 0.91

Typical Dose (MBq) 481

Typical Patients/week 40

Uptake Time (hr) 1

Imaging Time (hr) 0.5

Percentage of activity secreted prior to scan 15%

Important: see summary for final recommendations

Barrier T Distance (m) Weekly Dose Equiv. Transmission Factor Required Shielding

A-B Control Room 1 4.10 27.9 3.585 None mm Pb

B-C Corridor 0.2 2.89 56.1 1.781 None mm Pb

C-D Corridor 0.2 4.10 27.9 3.585 None mm Pb

D-A Corridor 0.2 2.89 56.1 1.781 None mm Pb

Ceiling (Office) 1 5.40 0.4 49.747 None mm Pb

Floor (Corridor & Open Space) 0.2 6.30 0.3 338.553 None mm Pb

PET Shielding Calculations

PET/CT Scan Room

Uptake Room Calculations

Patient Dose

Rate Constant

(uSv-m /MBq-h)

Dose Rate

Constant (uSv-m /MBq-h)

Dose Reduction

Factor over time

Uptake

Dose Reduction

Factor over time

Imaging

FDG 0.092 0.143 0.83 0.91

Typical Dose (MBq) 481

Typical Patients/week 14

Uptake Time (hr) 1

Imaging Time (hr) 0.5

Barrier T Distance (m) Weekly Dose Equiv. Weekly Limit (uSv) Transmission Factor

E-F Corridor 0.2 1.91 141.0 20.0 0.709

G-H Uptake 2C121B 0.2 1.98 131.2 20.0 0.762

F-G Outside 0.025 1.91 141.0 20.0 5.676

E-H Corridor 0.2 1.98 131.2 20.0 0.762

Ceiling (Office) 1 5.40 17.6 20.0 1.134

Floor (Storage) 0.05 6.30 13.0 20.0 30.875 None None

PET Shielding Calculations

Uptake Room 2C120

Required Pb (mm) Required Pb (inches)

2.797 1/9

None None

2.250 1/11

None None

2.250 1/11

Patient Dose

Rate Constant

(uSv-m /MBq-h)

Dose Rate

Constant (uSv-m /MBq-h)

Dose Reduction

Factor over time

Uptake

Dose Reduction

Factor over time

Imaging

FDG 0.092 0.143 0.83 0.91

Typical Dose (MBq) 481

Typical Patients/week 13

Uptake Time (hr) 1

Imaging Time (hr) 0.5

Barrier T Distance (m) Weekly Dose Equiv. Weekly Limit (uSv) Transmission Factor

H-I Corridor 0.2 1.91 130.9 20.0 0.764

G-H Uptake 2C120 0.2 1.98 121.8 20.0 0.821

G-J Outside 0.025 1.91 130.9 20.0 6.112

I-J Uptake 2C121A 0.2 1.98 121.8 20.0 0.821

Ceiling (Office) 1 5.40 16.4 20.0 1.221

Floor (Storage) 0.05 6.30 12.0 20.0 33.250

PET Shielding Calculations

Uptake Room 2C121B

Required Pb (mm) Required Pb (inches)

2.233 1/11

None None

1.669 1/15

None None

1.669 1/15

None None

Patient Dose

Rate Constant

(uSv-m /MBq-h)

Dose Rate

Constant (uSv-m /MBq-h)

Dose Reduction

Factor over time

Uptake

Dose Reduction

Factor over time

Imaging

FDG 0.092 0.143 0.83 0.91

Typical Dose (MBq) 481

Typical Patients/week 13

Uptake Time (hr) 1

Imaging Time (hr) 0.5

Barrier T Distance (m) Weekly Dose Equiv. Weekly Limit (uSv) Transmission Factor

I-L Corrdor 0.2 1.91 130.9 20.0 0.764

I-J Uptake 2C121B 0.2 1.98 121.8 20.0 0.821

J-K Outside 0.025 1.91 130.9 20.0 6.112

K-L Hot Lab 0.5 1.98 121.8 100.0 1.642

Ceiling (Office) 1 5.40 16.4 20.0 1.221

Floor (Storage) 0.05 6.30 12.0 20.0 33.250

None None

PET Shielding Calculations

Uptake Room 2C121A

Required Pb (mm) Required Pb (inches)

2.233 1/11

None None

None None

1.669 1/15

None None