Nebraska Administrative Code
Topic - HEALTH AND HUMAN SERVICES SYSTEM
Title 180 - CONTROL OF RADIATION
Chapter 20 - THERAPEUTIC RADIATION MACHINES FOR HUMAN USE
Appendix 20-A - INFORMATION ON RADIATION SHIELDING REQUIRED FOR PLAN REVIEWS

I. ALL THERAPEUTIC RADIATION MACHINES MUST SUBMIT THE FOLLOWING INFORMATION:

(A) Basic information including: name and telephone number of the individual responsible for preparation of the shielding plan; name and telephone number of the supervisor at the registrant's facility; and the street address, including room number of the therapeutic radiation machine. The plan should also indicate whether this is a new structure or a modification to existing structure or structures;

(B) All wall, floor, and ceiling areas struck by the useful beam must have primary barriers; and

(C) Secondary barriers must be provided in all wall, floor, and ceiling areas not having primary barriers.

II. THERAPEUTIC RADIATION MACHINES UP TO 150 KILOVOLTS (KV) - PHOTONS ONLY. In addition to the information listed in Section I, registrants using therapeutic radiation machines that produce only photons with a maximum energy less than or equal to 150 kilovolts (kV) must submit shielding plans which contain, at a minimum, the following additional information:

(A) Equipment specifications, including the manufacturer and model number of the therapeutic radiation machine, as well as the maximum technique factors;

(B) Maximum design workload for the machine including total weekly radiation output, expressed in gray or rad, or air kerma at 1 meter, total beam-on time per day or week, the average treatment time per patient, along with the anticipated number of patients to be treated per day or week;

(C) A facility blueprint or drawing indicating: scale, 0.25 inch = 1 foot is typical; direction of North; normal location of the therapeutic radiation machine's radiation port or ports; the port's travel and traverse limits; general direction or directions of the useful beam; locations of any windows and doors; and the location of the therapeutic radiation machine control panel. If the control panel is located inside the therapeutic radiation machine treatment room, the location of the operator's booth must be noted on the plan and the operator's station at the control panel must be behind a protective barrier sufficient to ensure compliance with 180 NAC 4-005;

(D) The structural composition and thickness or lead or concrete equivalent of all walls, doors, partitions, floor, and ceiling of the room or rooms concerned;

(E) The type of occupancy of all adjacent areas inclusive of space above and below the room or rooms concerned. If there is an exterior wall, show distance to the closest area or areas where it is likely that individuals may be present; and

(F) At least one example calculation which shows the methodology used to determine the amount of shielding required for each physical condition, primary and secondary or leakage barriers, restricted and unrestricted areas, entry door or doors and shielding material in the facility:

(i) If commercial software is used to generate shielding requirements, also identify the software used and the version or revision date.

(ii) Submit quality control sample calculations to verify the result obtained with the software.

III. THERAPEUTIC RADIATION MACHINES OVER 150 KILOVOLTS (KV). In addition to the information listed in Section I, registrants using therapeutic radiation machines that produce photons with a maximum energy in excess of 150 kilovolts (kV) or electrons must submit shielding plans which contain, as a minimum, the following additional information:

(A) Equipment specifications including the manufacturer and model number of the therapeutic radiation machine, and gray (rad) at the isocenter and the energy or energies and type or types of radiation produced, photon or electron. The target to isocenter distance must be specified;

(B) Maximum design workload for the machine including total weekly radiation output, expressed in gray or rad at 1 meter, total beam-on time per day or week, the average treatment time per patient, along with the anticipated number of patients to be treated per day or week;

(C) Facility blueprint or drawing [including both floor plan and elevation views] indicating relative orientation of the therapeutic radiation machine, scale, 0.25 inch = 1 foot is the typical scale, type or types, thickness and minimum density of shielding material or materials, direction of North, the locations and size of all penetrations through each shielding barrier, ceiling, walls and floor, as well as details of the door or doors and maze;

(D) The structural composition and thickness or concrete equivalent of all walls, doors, partitions, floor, and ceiling of the room or rooms concerned;

(E) The type of occupancy of all adjacent areas inclusive of space above and below the room or rooms concerned. If there is an exterior wall, show distance to the closest area or areas where it is likely that individuals may be present;

(F) Description of all assumptions that were in shielding calculations including, but not limited to, design energy, room may be designed for 6 megavolt (MV) unit although only a 4 megavolt (MV) unit is currently proposed, work load, presence of integral beam stop in unit, occupancy and use or uses of adjacent areas, fraction of time that useful beam will intercept each permanent barrier, walls, floor and ceiling, and expected radiation exposure in both restricted and unrestricted areas; and

(G) At least one example calculation which shows the methodology used to determine the amount of shielding required for each physical condition, primary and secondary or leakage barriers, restricted and unrestricted areas, small angle scatter, entry door or doors and maze, and shielding material in the facility:

(i) If commercial software is used to generate shielding requirements, also identify the software used and the version or revision date; and

(ii) If the software used to generate shielding requirements is not in the open literature, also submit quality control sample calculations to verify the result obtained with the software.

IV. NEUTRON SHIELDING. In addition to the information listed in Section III, registrants using therapeutic radiation machines that are capable of operating above 10 megavolts (MV) must submit shielding plans which contain, as a minimum, the following additional information:

(A) The structural composition, thickness, minimum density and location of all neutron shielding material;

(B) Description of all assumptions that were used in neutron shielding calculations including, but not limited to, neutron spectra as a function of energy, neutron fluence rate, absorbed dose and dose equivalent, due to neutrons, in both restricted and unrestricted areas;

(C) At least one example calculation which shows the methodology used to determine the amount of neutron shielding required for each physical condition, restricted and unrestricted areas, entry door or doors and maze, and neutron shielding material utilized in the facility:

(i) If commercial software is used to generate shielding requirements, also identify the software used and the version or revision date; and (ii) If the software used to generate shielding requirements is not in the open literature, also submit quality control sample calculations to verify the results obtained with the software; and

(D) The method or methods and instrumentation that will be used to verify the adequacy of all neutron shielding installed in the facility.

V. REFERENCES. References for shielding designs are as follows and are available for viewing at the Department of Health and Human Services, Division of Public Health, Office of Radiological Health, 301 Centennial Mall South, 3rd Floor, Lincoln, Nebraska 68509: