Biomaterial Database

Backscatter dose perturbation at high atomic number interfaces in megavoltage photon beams. 1989

I J Das, and F M Kahn

Department of Therapeutic Radiology, University of Minnesota Hospital, Minneapolis 55455.

Most computer algorithms used clinically for photon beam treatment planning are unable to predict the effect of electron backscattering on dose distribution from high atomic number materials. It has been observed that there is a significant dose enhancement at such an interface. We define the dose enhancement in terms of backscatter dose factor (BSDF), which depends on the energy of the photon beam, thickness and width of the inhomogeneity, distance from the interface, and the atomic number of the inhomogeneity. For all energies studied, the dose fall-off is initially very rapid and disappears beyond a few millimeters upstream from the interface. Empirically derived equations are presented for dose calculation at the interfaces of various media, including bone and soft tissue, for photon energies in the range of Co-60 gamma rays to 24 MV x rays.

UI	MeSH Term	Description	Entries
D011879	Radiotherapy Dosage	The total amount of radiation absorbed by tissues as a result of radiotherapy.	Dosage, Radiotherapy,Dosages, Radiotherapy,Radiotherapy Dosages
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
D011881	Radiotherapy, Computer-Assisted	Computer systems or programs used in accurate computations for providing radiation dosage treatment to patients.	Computer-Assisted Radiotherapy,Radiation Therapy, Computer-Assisted,Computer-Assisted Radiation Therapy,Computer Assisted Radiation Therapy,Computer Assisted Radiotherapy,Computer-Assisted Radiation Therapies,Computer-Assisted Radiotherapies,Radiation Therapies, Computer-Assisted,Radiation Therapy, Computer Assisted,Radiotherapies, Computer-Assisted,Radiotherapy, Computer Assisted,Therapies, Computer-Assisted Radiation,Therapy, Computer-Assisted Radiation
D011882	Radiotherapy, High-Energy	Radiotherapy using high-energy (megavolt or higher) ionizing radiation. Types of radiation include gamma rays, produced by a radioisotope within a teletherapy unit; x-rays, electrons, protons, alpha particles (helium ions) and heavy charged ions, produced by particle acceleration; and neutrons and pi-mesons (pions), produced as secondary particles following bombardment of a target with a primary particle.	Megavolt Radiotherapy,High-Energy Radiotherapy,Radiotherapy, Megavolt,High Energy Radiotherapy,Radiotherapy, High Energy
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012542	Scattering, Radiation	The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Radiation Scattering,Radiation Scatterings,Scatterings, Radiation