Determination of the Photon Fluency using Monte Carlo Simulation (página 2)

Figure No.3 The position of the random
axes concerning to the internal wall of the Man-hole, and
parameters of the second scattering on the wall in the Man-hole,
and b) projection on the YZ plane.

For the analysis of the second Compton scattering it was
used the similar basic like the first scattering.

For the geometrical analysis it was placed the axes
coordinate randomly just on one point of area of internal wall of
the MH, where values X2P, Y and Z are defined (See Figure No. 3
a) ), which will define the angles related to two axes (a12 and
a22 with y axe, and ÃY12 and ÃY22 with
z). The randomly way are generate the angles a and
ÃY correspondent to y and z
respectively, as well as a probability between 0 and 1. Then, if
the probability is lesser than and equal of occurring Compton
effect, and the a and ÃY are between a12 and a22, and
ÃY12 and ÃY22 respectively the photon will go out
across the Man-hole to the hall.

MODULE FOR RADIOLOGICAL PROTECTION ANALYSIS
AT THE ENTRANCE OD THE MH

Here, the Absorbed Dose Rate in reference
conditions is taken for calculating the initial value which
should be decreased by inverse square law and "Photon fluency" at
entrance of the MH, and increased by the relative dose factor
(A=35×35 cm2). The "Photon fluency" is defined as the ratio
between the number of photons generated from the source and the
numbers of them arrive to the entrance of the MH. The value
getting in the Annex I of this is around 0.5 x 10-6.

Conclusion

According to the result obtained by the
subroutine, for its geometrical data of the local and Man-hole it
is possible to design this sort of local for Cobalt-therapy
facility because of the absorbed dose rate is equal and lesser
than the absorbed dose rate limit for occupational personnel (0.2
mSv/week)

Bibliography

[Kha92] F. M. Khan. The Physics of
Radiation Therapy. Lppincott Williams & Wilkins. USA,
1992.

[Bie01] A. F. Bielajew. Fundamentals of the
Monte Carlo method for neutral and charged particle transport.
Ann Arbor, Michigan, 2001

Authors:

Lic. Terman Frómeta
Castillo

Instituto Superior Minero
Metalúrgico de Moa (ISMM) – Departamento de
Física

Lic. Eider Sánchez

Lic. William Martínez
Domínguez

Hospital Oncológico "Conrado
Benítez", Santiago de Cuba