Biomaterial Database

Shielding at the egress of a 23 mV linear accelerator. 1993

A S Trappier, and L P Johnson

Physics Department, Medgar Evers College (CUNY), Brooklyn.

Radiation shielding is required in radiotherapy accelerators to limit the dose equivalent rate from x-rays produced at the target in all directions except that of the useful forward directed beam. Calculations were made in terms of weekly workload of 50,000 cGy delivered to the isocenter per 5-day week, treating 25 patients per day at 400 cGy per patient. It is desirable to reduce the total exposure at the maze door below 30 Rem (0.30 Sv)/wk assuming full-time occupancy. The maze was designed to reduce the neutron dose to an acceptable level by slowing the neutrons to thermal velocities and then absorbing them in a low Z material in the egress.

UI	MeSH Term	Description	Entries
D009502	Neutrons	Electrically neutral elementary particles found in all atomic nuclei except light hydrogen; the mass is equal to that of the proton and electron combined and they are unstable when isolated from the nucleus, undergoing beta decay. Slow, thermal, epithermal, and fast neutrons refer to the energy levels with which the neutrons are ejected from heavier nuclei during their decay.	Neutron
D010315	Particle Accelerators	Devices which accelerate electrically charged atomic or subatomic particles, such as electrons, protons or ions, to high velocities so they have high kinetic energy.	Betatrons,Linear Accelerators,Accelerator, Linear,Accelerator, Particle,Accelerators, Linear,Accelerators, Particle,Betatron,Linear Accelerator,Particle Accelerator
D011829	Radiation Dosage	The amount of radiation energy that is deposited in a unit mass of material, such as tissues of plants or animal. In RADIOTHERAPY, radiation dosage is expressed in gray units (Gy). In RADIOLOGIC HEALTH, the dosage is expressed by the product of absorbed dose (Gy) and quality factor (a function of linear energy transfer), and is called radiation dose equivalent in sievert units (Sv).	Sievert Units,Dosage, Radiation,Gray Units,Gy Radiation,Sv Radiation Dose Equivalent,Dosages, Radiation,Radiation Dosages,Units, Gray,Units, Sievert
D011835	Radiation Protection	Methods and practices adopted to protect against RADIATION.	Protection, Radiation
D011878	Radiotherapy	The use of IONIZING RADIATION to treat malignant NEOPLASMS and some benign conditions.	Radiotherapy, Targeted,Targeted Radiotherapy,Radiation Therapy,Radiation Therapy, Targeted,Radiation Treatment,Targeted Radiation Therapy,Radiation Therapies,Radiation Therapies, Targeted,Radiation Treatments,Radiotherapies,Radiotherapies, Targeted,Targeted Radiation Therapies,Targeted Radiotherapies,Therapies, Radiation,Therapies, Targeted Radiation,Therapy, Radiation,Therapy, Targeted Radiation,Treatment, Radiation
D004867	Equipment Design	Methods and patterns of fabricating machines and related hardware.	Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D001703	Biophysics	The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.	Mechanobiology
D055592	Biophysical Phenomena	The physical characteristics and processes of biological systems.	Biophysical Concepts,Biophysical Processes,Biophysical Phenomenon,Biophysical Process,Biophysical Concept,Concept, Biophysical,Concepts, Biophysical,Phenomena, Biophysical,Phenomenon, Biophysical,Process, Biophysical,Processes, Biophysical