Biomaterial Database

Calculated depth dose distributions for proton beams in some low-Z materials. 1997

H Palmans, and F Verhaegen

Department of Biomedical Physics, University of Gent, Belgium.

The extended use of proton beams in clinical radiotherapy has increased the need to investigate the accuracy of dosimetry for this type of beam. As for photon and electron beams, Monte Carlo simulations are a useful tool in the study of proton dosimetry. The existing proton Monte Carlo code PTRAN developed for dosimetry purposes is designed for transport of protons in homogeneous water only. In clinical proton dosimetry as well as in treatment conditions several other materials can be present, such as plastic phantoms, plastic modulator wheels and several materials in ionization chambers. To investigate the transport of protons in other media we started from the PTRAN code, and implemented proton transport in other materials including heterogeneous systems composed of different materials. With this extended code, calculations of depth dose distributions for some low-Z materials are performed and compared with those obtained for water. The results show that for plastics (PMMA, polystyrene and A150) the depth dose characteristics are comparable to those of water. For graphite, air and aluminium larger differences are observed. The differences between water and the low-Z materials studied here are small but can be important for accurate dosimetry.

UI	MeSH Term	Description	Entries
D008768	Methylmethacrylates	The methyl esters of methacrylic acid that polymerize easily and are used as tissue cements, dental materials, and absorbent for biological substances.
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
D010969	Plastics	Polymeric materials (usually organic) of large molecular weight which can be shaped by flow. Plastic usually refers to the final product with fillers, plasticizers, pigments, and stabilizers included (versus the resin, the homogeneous polymeric starting material). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Plastic
D011137	Polystyrenes	Polymerized forms of styrene used as a biocompatible material, especially in dentistry. They are thermoplastic and are used as insulators, for injection molding and casting, as sheets, plates, rods, rigid forms and beads.	Polystyrol,Polystyrene,Polystyrols
D011880	Radiotherapy Planning, Computer-Assisted	Computer-assisted mathematical calculations of beam angles, intensities of radiation, and duration of irradiation in radiotherapy.	Computer-Assisted Radiotherapy Planning,Dosimetry Calculations, Computer-Assisted,Planning, Computer-Assisted Radiotherapy,Calculation, Computer-Assisted Dosimetry,Calculations, Computer-Assisted Dosimetry,Computer Assisted Radiotherapy Planning,Computer-Assisted Dosimetry Calculation,Computer-Assisted Dosimetry Calculations,Dosimetry Calculation, Computer-Assisted,Dosimetry Calculations, Computer Assisted,Planning, Computer Assisted Radiotherapy,Radiotherapy Planning, Computer Assisted
D003198	Computer Simulation	Computer-based representation of physical systems and phenomena such as chemical processes.	Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
D006108	Graphite	An allotropic form of carbon that is used in pencils, as a lubricant, and in matches and explosives. It is obtained by mining and its dust can cause lung irritation.	Graphene
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000388	Air	The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
D000535	Aluminum	A metallic element that has the atomic number 13, atomic symbol Al, and atomic weight 26.98.	Aluminium,Aluminium-27,Aluminum-27,Aluminium 27,Aluminum 27