Engineering topics

Khandelwal, G. S.

Publications and source records attributed to Khandelwal, G. S..

41 records · Page 3

NASA NTRS1974

Proton tissue dose for the blood forming organ in human geometry: Isotropic radiation

A computer program is described which calculates doses averaged within five major segments of the blood forming organ in the human body taking into account selfshielding of the detailed body geometry and nuclear star effects for proton radiation of arbitrary energy spectrum (energy less than 1 GeV) and isotropic angular distribution. The dose calculation includes the first term of an asymptotic series expansion of transport theory which is known to converge rapidly for most points in the human body. The result is always a conservative estimate of dose and is given as physical dose (rad) and dose equivalent (rem).

Khandelwal, G. S.↗

NASA NTRS1974

Proton dose approximation in arbitrary convex geometry

An expansion is derived for the solution to the transport equation in two dimensions subject to boundary conditions given for an arbitrary convex region. Questions of high-energy transport are considered along with the properties of the dose response function. The expansion of the solution of the transport equation is presented in terms of a parameter which measures the lateral dispersion of an unidirectional beam. This parameter is usually small and the expansion is expected to converge rapidly. The dominant term in the expansion is related to fluence-to-dose conversion factors in a semiinfinite slab for normal incidence. A convenient parameterization of the conversion factors is provided along with numerical examples.

Wilson, J. W.↗

NASA NTRS1974

Study of blood forming organ dose as a function of proton environment

It is demonstrated that a dosimeter which consists of four ion chambers, each with different wall thickness, is able to reproduce the BFO dose with reasonable accuracy. This generalized dosimetric system is only slightly more complex than dosimeters in current use. This preliminary development had two built-in assumptions; the isotropicity of the radiation and the neglect of nuclear reaction effects. Only the nuclear reaction effects have been calculated.

Khandelwal, G. S.↗

NASA NTRS1974

Geometric correction for spherical ion chambers

The dose at the center and the average dose of a spherical ion chamber were calculated for various inner and outer radii for a radiation spectrum described by E raised to a negative exponent, where the exponent ranges from 2.5 to 7. When the ratio of the chamber's inner radius to the wall thickness is small, the dose at the center does not deviate significantly from the average dose. However, when the ratio equals 5, the center dose exceeds the average dose by about 100% for an exponent of 7, and by about 30% for an exponent of 2.5.

Khandelwal, G. S.↗

NASA NTRS1973

Proton dosimeter design for distributed body organs.

The design of a real-time rem-rad dosimeter with sufficient generality for inclusion of dose distribution factors for space applications is discussed. This generalized dosimetric system is only slightly more complex than dosimeters in current use.

Khandelwal, G. S.↗