16-Shielding Design Report.pdf

Shielding Specifications, LBJ EC 1137 & 1138 Radiographic Replacement June 9, 2025

Shielding specifications report for the radiographic equipment replacement in rooms EC 1137 and 1138 at the LBJ Hospital.

This report is generated due to the replacement of the radiographic units located in the Emergency Center, Room 1137 and Room 1138 at the Lyndon B. Johnson Hospital, 5656 Kelley St, Houston, TX 77026. The purpose of this report is to provide the structural shielding design specifications for the new radiographic machine installation.

Description of the rooms to be shielded:

Room EC 1137 measures 18’33/8” x 14’815/16”. The room is adjacent to a patient waiting area on the north, room EC 1138 on the south, a public corridor and the technologist area on the east, and a public corridor on the west.

Room EC 1138 measures 16’47/8” x 14’815/16”. The room is adjacent to room EC 1137 on the north, two exam isolation rooms on the south, a registration office on the east and a public corridor on the west.

The EC department is located on Level 1 of the hospital building. The floor above (Level 2) is occupied by offices and other hospital spaces.

The following conditions apply:

(NOTE: if any of these conditions are incorrect or underestimate the workload, please bring this to the attention of the Medical Physicist immediately so that a corrected report can be issued):

1. Shielding design specifications were based on the Philips equipment layout dated 7/22/2024, provided by Tarek Rahhal, Senior Project Manager at Harris Health.

2. There is currently lead shielding installed in the room, however this report reassesses the shielding requirements based on the specifications of the new radiographic units.

3. The NCRP Report 147: Structural Shielding Design for Medical X-ray Imaging Facilities, was used as the guideline for the shielding design calculations.

4. Shielding design specifications are intended for one radiographic unit with one wall bucky in each room. The location of the new wall bucky will remain the same as the current wall bucky.

5. This shielding analysis and radiation safety assessment is based on an estimated weekly workload of 125 patients. This is a very conservative workload assumption (selected to be high).

6. Radiation scatter and primary radiation per patient were assigned according to the NCRP Report 147 recommendations for radiographic procedures, including table and wall bucky imaging.

7. Design criteria are based on the following requirements of the State of Texas:

a. Shielding for uncontrolled areas are based on the State of Texas

Administrative Code Title 25 Part 1 Chapter 289 Subchapter E Rule §289.231(o)(1)(A) & (B) which states the TEDE to individual members of the public from exposure to radiation from radiation machines does not exceed

0.5 rem (5 mSv) in a year, exclusive of the dose contribution from background radiation, exposure of patients to radiation for the purpose of medical diagnosis or therapy, or to voluntary participation in medical research programs; and (B) the dose in any unrestricted area from registered external sources does not exceed 0.002 rem (0.02 mSv) in any 1 hour.

b. Shielding for controlled areas is based on the State of Texas Administrative Code Title 25 Part 1 Chapter 289 Subchapter E Rule §289.231(m)(1)(A) which states that the registrant shall control the occupational dose to individuals to an annual TEDE of not more than 5 rems (0.05 Sv).

c. Recommended shielding is additionally designed for protection to conservatively low levels necessary to meet the spirit of the State of Texas Statute §289.231(l) which states that the registrant shall use, to the extent practical, procedures and engineering controls based upon sound radiation protection principles to achieve occupational doses and public doses that are ALARA. An ALARA target of 5 mSv per year for occupational radiation workers is used in many clinics and was applied in this design. An ALARA target of 1 mSv per year is recommended for members of the public and is used in the design provided in this report.

8. All shielding recommendations are minimum thickness requirements. Shielding may be thicker, if desired.

9. Unless otherwise noted, all lead shielding for walls is to extend from the floor to at least seven (7) feet above the floor.

10. All leaded gypsum wallboard (sheetrock) must be installed with an overlapping flap or strip of equivalent-thickness lead between sections to seal the junctions.

11. All areas of any wall under the seven (7) feet limit that have holes (as for mounting electric boxes or telephone connections etc.), must have the boxes shielded on the back with a patch at least 1” larger on each side than the hole. For the intake grills of air ducts, shield the opposite and surrounding walls of the air-duct at the level of the grill. For solid concrete columns, no extra lead shielding is needed. Call the consultant physicist at 713-500-7671 if there are any questions on shielding any such areas.

12. Lead caps for nails or screws used to hang sheetrock are not necessary.

13. All windows in the room must have the same lead thickness equivalent to the walls, unless otherwise specified.

14. All door and window frames must have the same lead thickness equivalent to that of the door or window.

Recommended shielding:

The diagrams below specify the shielding requirements for rooms EC 1137 and EC 1138.

- Doors indicated by the green line require 1/32-inch lead thickness.

- Walls indicated by the red line require 1/16-inch leaded sheetrock.

- The Control Room Window must have the same lead-equivalent thickness as the

Control Room wall.

- The ceiling and floor do not require shielding.

PLEASE NOTE:

- Rooms EC 1137 and EC 1138 have lead shielding currently in the walls, doors, and control room windows. If the existing shielding is penetrated or damaged during construction, shielding has to be corrected following the specified lead thickness as shown in this report.

- It is strongly recommended to contact the Medical Physicist to conduct a visual inspection of the shielding installed prior to closing up the walls in the room. The visual inspection allows to identify discrepancies in the shielding and correct them before finalizing the walls.

Reviewed and approved by:

Patricia Svolos, Ph.D., DABR Radiation Safety Officer, Lyndon B. Johnson Hospital UT Medical Physics Service Group University of Texas Health Science Center at Houston Texas License FMP02000128 Email: patricia.t.svolos@uth.tmc.edu Phone: 713-500-7656 mailto:patricia.t.svolos@uth.tmc.edu