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