Beta-Ray Dose Distributions From Point Sources in an Infinite Water Medium

Abstract

Membranes that exclude water but are permeable to radon can extend the range of environments where many radon detection systems could operate. We have studied the permeation of 222Rn through polypropylene membranes separating air and water phases. The permeation coefficient and the activation energy were calculated for various conditions. Potential applications, such as in situ detection of radon in water, are discussed.

Enhancing Nanoparticle Accumulation and Retention in Desmoplastic Tumors via Vascular Disruption for Internal Radiation Therapy

“…177 Lu was therefore compared to 90 Yttrium ( 90 Y), a clinically used radioisotope 22, 23 which has a max beta energy of 2.28 MeV and a half-life of 2.67 days. Figure 7A compares the relative decay of 177 Lu and 90 Y over a period of seven days, while Figure 7B compares the previously calculated dose kernels for point sources of the two isotopes in units of absorbed dose (nanogray per decay per h over a given surface area) 24, 25. While 90 Y decays more quickly than 177 Lu, its higher beta energy allows more energy to reach farther away from the source and impart more energy per interaction.…”

Experimental and theoretical dosimetry of the RIC-100 phosphorus-32 brachytherapy source for implant geometries encountered in the intraoperative setting

“…The rate of energy deposited per unit area should be independent of medium (16). Depth in the material is represented by the variable X.…”

Accurate determination of dose‐point‐kernel functions close to the origin using Monte Carlo simulations

“…Compilations for electron, beta and photon sources have been reported, the most recent ones being based exclusively on Monte Carlo simulations. [1][2][3][4][5][6][7] In Monte Carlo simulations, the dose around a point source is obtained by tallying the energy deposited in thin concentric spherical shells around the source origin per particle decay. Alternative techniques to the spherical shell analog scoring have been developed for photons ͑surface crossing estimator͒ but there are no alternatives to analog scoring for electrons.…”

“…It is then possible to calculate the kernel function F(r) for any electron/beta emitting isotope by folding the monoenergetic functions j(r/r E ,E) over the isotope's electron energy spectrum. This standard method has been used by Cross et al 5,6 to produce a compilation of beta-ray dose distribution in water for 120 isotopes. In this earlier work by Cross et al, the monoenergetic functions j(r/r E ,E) were calculated using a derivative of the Monte Carlo code ETRAN with analog scoring and using the mean radius value R M defined as the arithmetic mean of the inner and outer radius of the shell of interest.…”

“…However, for the innermost shells with r/r E Ͻ0.125, the Monte Carlo results were discarded and the dose at rϭ0 was estimated based on the restricted stopping power. 5 In the present work, we have extended the compilation of Cross et al to 546 beta emitters using our own sets of functions j(r/r E ,E) calculated using EGSnrc and we present an evaluation method that allows determination of the effective radius R D defined as the distance of a hypothetical zero thickness detector from the source that gives the same result as the finite-thickness detector. As will be seen, our approach avoids the approximation made by Cross et al at rϭ0 and uses Monte Carlo results consistently at distances very close to the origin.…”