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Manuscript Title: Gamma-radiation dosimetry for arbitrary source and target geometry.
Authors: L.B. Hubbard
Program title: DOSEI
Catalogue identifier: ACMG_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 2(1971)449
Programming language: Fortran.
Computer: IBM 360/75 AND 91.
Operating system: OS 360.
RAM: 26K words
Word size: 32
Keywords: Radiation physics, Dosimetry, Dose, Absorption, Gamma-ray, Photon, Energy deposition.
Classification: 21.1.

Revision history:
Type Tit le Reference
correction 000A CORRECTION 05/03/73 See below
adaptation 0001 DOSEI IMPROVEMENTS See below

Nature of problem:
The program DOSE1 calculates the first collision dose in the formalism of absorbed fractions for gamma-rays in arbitrary finite geometry of source, absorber and target. The basic unit of the program is the subroutine ATINTG which calculates the attenuation term. This attenuation term is applicable to all examples of exponential absorption in an arbitrary absorption distribution, provided that, the linear absorption coefficient is known as a function of position.

Solution method:
The total volume, including both source and target, is subdivided into small parallelepipeds. The source strength and target absorption for each of these elementary volumes are placed at the geometric center. The absorption is calculated as expotential, exp(-mu x), for each elementary volume traversed from the center of the source volume to the center of target volume. The contributions for all sources are summed to give point-specific absorbed fractions for each elementary volume. The total absorbed fraction is the average of the point functions. The approach used here differs markedly from the current dosimetry procedure of using the Monte-Carlo method.

Restrictions:
This method is exact in principle for only the first collision dose, since expotential absorption is used. For bodies whose linear dimensions are much less than the mean free photon path, this is a reasonable approximation. For slightly larger volumes an approximation assuming an effective absorption coefficient has some validity. The program is completely general in terms of geometry. It is suitable for distributed or point sources both internal and external to the target. For some situations the dimensions of the subscripted variables would require modification.

Running time:
The execution time for this program is very sensitive to the input parameters. Execution time will vary approximately as N**7/3 where N is the number of elementary sub-volumes. For the rather simple problem exhibited in the sample output the execution times are 0.6 seconds on the IBM-360/75 and 0.2 seconds on the IBM-360/91. Compile times are 11 seconds and 2.5 seconds for the IBM 360/75 and IBM-360/91, respectively.

CORRECTION SUMMARY
Manuscript Title: Gamma-radiation dosimetry for arbitrary source and target geometry. (C.P.C. 2(1971)449).
Authors: L.B. Hubbard
Program title: 000A CORRECTION 05/03/73
Catalogue identifier: ACMG_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 5(1973)395
Classification: 21.1.

ADAPTATION SUMMARY
Manuscript Title: First collision gamma-ray dose.
Authors: L.B. Hubbard
Program title: 0001 DOSEI IMPROVEMENTS
Catalogue identifier: ACMG_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 6(1973)240
Programming language: Fortran.
Computer: IBM 360/65.
RAM: 2K words
Word size: 32
Classification: 21.1.

Nature of problem:
This adaptation consists of three changes. Two of these speed execution. The other makes the results more accurate.

Solution method:
A geometric symmetry in the attenuation integral speeds execution. When reflectional or rotational symmetries exist in both source and matter distributions these can be utilized to speed execution. The attenuation in the source and target sub-volumes is added by three formulae adapted from spheres; two are in the literature and one is based on a point source.

Restrictions:
The attenuation will be calculated to within 2% provided the geometrical representation is good and the x, y, and z spacings are equal and less than one mean free path.

Running time:
Total execution time for the sample run required 1.2 min.