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Linac Door, Neutron Shielded Door
The Madoors USA Linac Neutron Shielded Door is a custom-manufactured, lead-lined and/or borated polyethylene filled core radiation shielding door system with steel faces and edges — engineered for linear accelerator radiation and oncology facilities, particle accelerator vaults, and high-radiation treatment rooms requiring certified neutron and gamma radiation shielding performance. With over 40 years of custom manufacturing experience in neutron shielded door production, Madoors USA designs each door individually to the specific project requirements — based on linear accelerator energy output, radiation type, orientation to radiation sources, primary beam configuration, and overall room design — in sliding or hinged configurations for new construction and retrofit applications, in weights up to 40,000 lbs per door.
All Madoors USA Automatic Motorized Linac Gate Doors, High Radiation Doors, and Linear Accelerator Vault Doors meet all applicable requirements of the National Council on Radiation Protection and Measurements — including NCRP reports covering radiation protection design guidelines for 0.1 to 100 MeV particle accelerator facilities and structural shielding design for megavoltage X-ray and gamma-ray radiotherapy facilities. Door shielding material composition requirements are determined by a qualified health radiation physicist expert as defined by local and national codes.
TECHNICAL SPECIFICATIONS
Madoors USA Neutron Shielded Doors are available in the following shielding core configurations — selectable based on the radiation type, energy level, and shielding requirement determined by the qualified health radiation physicist for each specific project.
Lead-lined core — providing gamma ray attenuation through the high atomic number and density of lead. Lead is the primary shielding material for high-energy gamma radiation generated by megavoltage linear accelerators in radiotherapy facilities and by high-energy beam interactions at particle accelerator facilities. Lead thickness within the door core is determined by the linear accelerator energy output — expressed in MeV — and the required attenuation factor at the specific measurement point.
Borated polyethylene filled core — providing thermal neutron capture and fast neutron moderation through the combination of hydrogen nuclei in the polyethylene matrix — which moderate fast neutrons to thermal energies — and boron-10 nuclei which capture the thermalized neutrons. Borated polyethylene is the standard neutron shielding material for linear accelerator vault doors where neutron production from high-energy photon beam interactions with the room structure generates a significant neutron component in the radiation field.
Combined lead and borated polyethylene core — for facilities where both gamma and neutron shielding requirements must be simultaneously satisfied within a single door construction. The layering sequence of lead and borated polyethylene is determined by the specific radiation field composition and the order of interaction required for optimal attenuation — typically neutron moderation and capture layers followed by gamma attenuation layers for mixed radiation fields.
Steel faces and edges provide the outer structural shell of the door — maintaining door geometry under the operational loading of automated sliding or hinged operation at weights up to 40,000 lbs, and providing the structural connection interface for the door frame, hinge system, and drive mechanism.
Automatic motorized operation is available for both sliding and hinged configurations — providing reliable, powered opening and closing of the extremely heavy shielded door panels that cannot be manually operated at weights up to 40,000 lbs. Drive system selection and motor sizing are matched to the specific door weight, opening speed requirement, and operational cycle rate of each facility.
KEY FEATURES
Over 40 Years of Custom Neutron Shielded Door Manufacturing
Madoors USA brings over four decades of custom neutron shielded door manufacturing experience to every linac door project — the longest established track record available in the specialist radiation shielding door sector. This experience base encompasses the full evolution of linear accelerator technology from early cobalt-60 therapy units through to modern high-energy multi-MeV treatment accelerators, providing Madoors USA engineers with the practical knowledge base required to translate a qualified physicist's shielding specification into a practical, operable door design.
Project-Specific Custom Design — 6 Key Parameters
Every Madoors USA neutron shielded door is custom designed to the specific project requirements across six key engineering parameters — linear accelerator energy output in MeV, radiation type — photon, electron, neutron, or mixed — orientation of the door relative to the primary and secondary radiation sources, primary beam configuration — field size, gantry angle range, and beam direction — and overall treatment room or vault design geometry including maze configuration, wall thickness, and door portal dimensions. This six-parameter custom design approach ensures that the door provides exactly the required radiation shielding performance without over-specification that would add unnecessary weight and cost.
Lead-Lined Core — Gamma Radiation Attenuation
Lead lining within the steel-faced door core provides the primary gamma radiation attenuation required at linear accelerator vault doors where megavoltage X-ray beams — typically 6 to 18 MeV for clinical radiotherapy — and the secondary radiation produced by beam-room interactions generate a significant photon dose at the door portal. Lead thickness is calculated by the health radiation physicist for the specific accelerator energy and the required transmitted dose rate at the door exterior to satisfy the applicable regulatory dose limit.
Borated Polyethylene Core — Neutron Moderation & Capture
Borated polyethylene filling provides the two-stage neutron attenuation required for high-energy linac vault doors — fast neutron moderation by the hydrogen-rich polyethylene matrix reduces fast neutron kinetic energy to thermal energies, and thermal neutron capture by boron-10 removes the thermalized neutrons from the radiation field. This two-stage process is the standard engineering approach for neutron shielding in linear accelerator vault doors at facilities operating above approximately 10 MeV where photoneutron production in the treatment room is significant.
Sliding & Hinged Configurations — New Construction & Retrofit
Both sliding and hinged door configurations are available for new construction and retrofit applications — with configuration selection based on the vault entrance geometry, available space alongside the door opening, and operational requirements of each specific facility. New construction projects allow the vault design to be optimized for the selected door configuration. Retrofit installations replace existing doors in existing vault openings — requiring the new door design to match the existing portal dimensions and drive mechanism infrastructure where possible.
Up to 40,000 lbs — Heavy-Duty Automated Operation
Doors up to 40,000 lbs — approximately 18,000 kg — per leaf require automated motorized drive systems capable of reliably opening and closing the extreme door mass in the operational cycle times required by the treatment schedule of an active radiotherapy department. Drive system selection — motor power, drive mechanism type, and speed controller specification — is matched to the specific door weight, required opening speed, daily cycle rate, and emergency response time of each facility.
NCRP Report Compliance — 0.1 to 100 MeV Particle Accelerators
All Madoors USA linac doors meet the applicable requirements of NCRP reports covering radiation protection design guidelines for 0.1 to 100 MeV particle accelerator facilities — confirming that the door design addresses the full energy range of medical and research linear accelerators from low-energy electron beam systems through to the highest-energy photon beam clinical accelerators. NCRP compliance satisfies the regulatory documentation requirements of radiation protection authorities in the United States and internationally where NCRP guidelines are adopted as the design standard for accelerator facility shielding.
Megavoltage X-Ray & Gamma-Ray Structural Shielding Compliance
Compliance with NCRP structural shielding design guidelines for megavoltage X-ray and gamma-ray radiotherapy facilities — the primary regulatory framework for clinical radiotherapy vault shielding design in the US — confirms that the door shielding specification satisfies the regulatory occupancy-weighted dose rate limits at the vault door exterior for both controlled and uncontrolled areas adjacent to the treatment vault.
Physicist-Specified Shielding Composition
The shielding material composition of every Madoors USA linac door — lead thickness, borated polyethylene thickness and density, and their arrangement within the door core — is determined by a qualified health radiation physicist expert as defined by local and national codes. This physicist determination requirement ensures that the door shielding is based on a rigorous, site-specific radiation field analysis rather than a generic specification — providing the regulatory compliance documentation required by radiation protection authorities for operating license issuance and periodic safety inspection.
DOOR SELECTION GUIDE BY APPLICATION
Clinical Radiotherapy Linear Accelerator — 6 to 18 MeV
Typically requires combined lead and borated polyethylene core — lead for primary photon beam and scattered gamma attenuation, borated polyethylene for photoneutron attenuation above approximately 10 MeV. Sliding door configuration is most common for treatment vault access due to the vault maze geometry and space efficiency. Physicist specification required for each treatment room based on accelerator model, energy, gantry rotation arc, and room dimensions.
Proton Therapy Gantry Vault
Requires specialized shielding composition for the high-energy proton beam — including secondary neutron shielding from proton beam interactions with the gantry structure and patient. Borated polyethylene content is typically higher than photon linac doors due to the higher neutron production associated with proton beam delivery. Physicist specification required for each vault based on proton beam energy, current, and gantry rotation geometry.
Research Particle Accelerator — 0.1 to 100 MeV
Custom composition based on the specific particle type, beam energy, beam current, and experimental area occupancy pattern — covering the full 0.1 to 100 MeV particle accelerator energy range referenced in the NCRP guidelines. Physicist specification is essential for research accelerator doors due to the wider range of particle types, energies, and experimental configurations compared to clinical therapy facilities.
Radiation Therapy Gamma-Ray Facility
For cobalt-60 and other gamma-ray therapy sources — primarily gamma shielding with lead-lined core without the borated polyethylene neutron shielding component required for high-energy photon linac facilities. Lead thickness determined by physicist for the specific source activity and treatment room geometry.
ASSEMBLY & INSTALLATION SEQUENCE
Physicist Specification Review
The health radiation physicist's shielding specification is received — confirming required lead thickness, borated polyethylene density and thickness, combined core arrangement, door dimensions, and maximum allowed transmitted dose rate at the door exterior. Door weight estimate is calculated from the specified shielding composition and dimensions.
Custom Engineering Design
The door structural design — steel face thickness, edge construction, core cavity dimensions, and connection geometry — is engineered for the specified shielding composition and the required door weight capacity of the automated drive system. Sliding or hinged configuration and drive system specification are confirmed.
Factory Core Manufacturing
Lead lining is cast or laminated to the specified thickness within the steel face and edge enclosure. Borated polyethylene filling is cast or prefabricated to the specified density and thickness within the remaining core cavity. Combined core assembly sequence and material interface geometry are verified against the physicist specification.
Steel Face & Edge Assembly
Steel faces and edges are assembled and welded around the shielding core — forming the complete door leaf to the confirmed dimensions. Door leaf weight is verified against the engineering specification before drive system sizing confirmation.
Drive System Installation at Vault Entrance
The motorized drive system — sized for the confirmed door weight and operational cycle requirement — is installed at the vault entrance portal. Sliding track or hinge system is installed and structural connection to the vault wall is verified for the full door weight loading.
Door Leaf Installation & Drive Connection
The heavy shielded door leaf is installed on the track or hinge system using specialist heavy-lift equipment appropriate for loads up to 40,000 lbs. Drive connection, door travel, and speed controller settings are verified.
Radiation Survey & Regulatory Compliance Documentation
A radiation protection survey is conducted with the door in the closed position — measuring transmitted dose rates at the door exterior and comparing against the physicist's design limits. Survey results are documented for submission to the radiation protection authority as part of the facility operating license application or renewal documentation.
DEPLOYMENT SCENARIOS & USE CASES
Madoors USA Linac Neutron Shielded Doors are specified for any radiation facility requiring custom physicist-specified shielding door systems.
- Clinical radiotherapy linear accelerator vault doors
- Proton therapy gantry vault neutron shielded doors
- Electron beam therapy vault radiation doors
- Research particle accelerator vault doors
- Cyclotron facility neutron shielded vault doors
- PET isotope production linac facility vault doors
- Nuclear medicine therapy vault radiation doors
- High-energy physics research accelerator vault doors
- Industrial electron beam accelerator vault doors
- Radiation sterilization facility vault shielded doors
- Non-destructive testing accelerator vault doors
- University research accelerator facility vault doors
- Military radiation research facility vault doors
- Synchrotron experimental area radiation vault doors
- Radiation calibration laboratory high-energy vault doors
- Category: Sliding Gate