Introduction to health physics (2nd edn)

Williams, Meghan

doi:10.1016/0306-4549(89)90096-0

Cited by 8 publications

(1 citation statement)

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“…Therefore for the very simple model that seems to be adequate for our purposes, we will assume equal cross sections for photoneutron production and we will base the number of radioactive atoms on the abundance of each element in tissue. Due to the great simplifications already made for these models, we further make simplified calculations according to Cember (1989), assuming an infinitely large medium containing a uniformly distributed isotope. The increase in dose from induced radioactivity was calculated to be approximately 0.01% of the intended VHE electron beam dose.…”

Section: Evaluation Of Bremsstrahlung and Neutron Productionmentioning

confidence: 99%

150-250 MeV electron beams in radiation therapy

et al. 2000

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High-energy electron beams in the range 150-250 MeV are studied to evaluate the feasibility for radiotherapy. Monte Carlo simulation results from the PENELOPE code are presented and used to determine lateral spread and penetration of these beams. It is shown that the penumbra is comparable to photon beams at depths less than 10 cm and the practical range (Rp) of these beams is greater than 40 cm. The depth dose distribution of electron beams compares favourably with photon beams. Effects caused by nuclear reactions are evaluated, including increased dose due to neutron production and induced radioactivity resulting in an increased relative biological effectiveness (RBE) factor of < 1.03.

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Section: Evaluation Of Bremsstrahlung and Neutron Productionmentioning

confidence: 99%

150-250 MeV electron beams in radiation therapy

et al. 2000

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The SFU/TRIUMF Radiochemistry Institute an intensive training program for radiopharmaceutical chemistry

Ruth

D’Auria

1993

Journal of Radioanalytical and Nuclear Chemistry, Articles

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Direct counting of soil wafers: An improved total alpha/beta screening analysis

Burnett

Wong

Clark

et al. 1998

J Radioanal Nucl Chem

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Although potentially very useful as a screening tool, currently-applied "gross" alpha/beta analyses are often considered unreliable by the environmental monitoring community. We describe here an alternative approach based on direct counting of pressed soil "wafers" to estimate total alpha/beta activities. The system was calibrated using a series of natural soils and sediment standards with total c~/[3 activities estimated by use of a combination of available certified values, equilibrium assumptions, and our own measurements. A set of 10 such standards that span a wide range of activities were prepared by thoroughly mixing several grams of selected NIST and IAEA natural matrix standards together with reagent grade cellulose in a 4:1 sample-to-binder ratio and pressing in a 40-mm stainless steel die. The resulting wafers, assumed to be at infinite thickness for expected radionuclides, were counted in a gas flow proportional counter set for simultaneous c~/[3 counting. Both the alpha and beta count rates increased in a linear, systematic manner with increasing total estimated activities. This technique should prove to be an inexpensive, simple, and waste-free approach for screening total radioactivity in soil samples. Introduction*"Gross" alpha and beta measurements are performed frequently as a screening analysis for assessing alpha and beta radioactivity in environmental samples. The results of these analyses are commonly used in making administrative decisions involving environmental remediation, transportation requirements, environmental assessments, and laboratory sample segregation. In many cases gross alpha/beta analyses are used as an initial screening tool to determine whether or not more detailed isotopic analyses are warranted. Unfortunately, current analysis techniques for gross radioactivities are perceived as being ambiguous and unreliable for many reasons. Some of these problems relate to the presence of radon progeny, the lack of well-characterized soil standards for calibrations, and the unpredictable absorption effects that soil has on counting results. 1 3 As a result, time consuming, expensive, and laborintensive isotopic analyses are often requested in cases where a dependable screening method would have been sufficient. This is clearly an inefficient use of our overall resources.Problems arising from existing techniques for gross alpha/beta analysis of soil include variable geometries, sample thicknesses, and quantitative evaluation of the mass absorption effects from variable amounts of soil. All these effects will significantly influence the detector efficiency for alpha-and beta-particle detection. It is clearly difficult to prepare, with an adequate degree of confidence, a homogenous and reproducible sample geometry using either a soil slurrying or partial dissolution technique -both common practices in the gross (,/[3 assay of soil. Problems also exist when total dissolution of soil is attempted because this usually involves the use of hydrofluoric and perchloric acids, which are restrict...

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Introduction to health physics (2nd edn)

Cited by 8 publications

References 0 publications

150-250 MeV electron beams in radiation therapy

150-250 MeV electron beams in radiation therapy

The SFU/TRIUMF Radiochemistry Institute an intensive training program for radiopharmaceutical chemistry

Direct counting of soil wafers: An improved total alpha/beta screening analysis

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