Biomaterial Database

Spectrally average conversion coefficients for air kerma to ambient dose equivalent for clinical linear accelerator. 2009

Marco A Frota, and Verginia R Crispim, and Ademir X Silva, and Alphonse Kelecom

Laboratório de Radiobiologia e Radiometria, Departamento de Biologia Geral, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, Caixa Postal 100.436-24001-970 Niterói, RJ, Brazil.

This work aims to calculate the conversion coefficients from air kerma to ambient dose equivalent, H*(10)/K(air) for photon beams produced by linear accelerators, such as the Clinac-4, Clinac-6, Clinac-18 and Clinac-2500, after transmission through primary barriers of radiotherapy treatment rooms. Concrete walls of thickness 1.0, 1.5 and 2.0m were irradiated with 30cmx30cm primary beam spectra. The transmitted spectra were calculated to obtain the conversion coefficients for beams found in radiotherapy services. The calculations were done using the MCNP-4B Monte Carlo code. The results indicate the need to use a factor of about 1.20 to obtain the ambient dose equivalent for radiation surveys near primary barriers using instruments calibrated in air kerma.

UI	MeSH Term	Description	Entries
D009010	Monte Carlo Method	In statistics, a technique for numerically approximating the solution of a mathematical problem by studying the distribution of some random variable, often generated by a computer. The name alludes to the randomness characteristic of the games of chance played at the gambling casinos in Monte Carlo. (From Random House Unabridged Dictionary, 2d ed, 1993)	Method, Monte Carlo
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
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
D002138	Calibration	Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output.	Calibrations
D000388	Air	The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
D017785	Photons	Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (From Hawley's Condensed Chemical Dictionary, 11th ed)