Extended gamma sources modelling using multipole expansion: Application to the Tunisian gamma source load planning

Study of the Photon Flux and the Dose Rate in the Vicinity of a <sup>60</sup>Co Gamma Irradiator

“…The reloading of the source can be done with or without permutation, which gives a large number of configurations (millions of configurations) [3]. We showed in our previous work [2] that this extended source behaves like a pencil source with a discrepancy less than one percent.…”

“…The other four are mounted around a 4 cm radius circle, downward the Z axis (Figure 1). The source rack contains 10 free housings allowing the addition of supplementary pencils in order to compensate the decrease of the activity [3]. The total source activity in August/2004 is about 1.81 PBq [5].…”

“…In order to determine the photon flux rates and the dose rates deposited in PMMA dosimeters placed in the vicinity of this irradiator, various measurements have been realized by the CNSTN researchers. These authors have also determined these two quantities using a calculation [3] [4] and a simulation by GEANT4 [5]- [8]. Their photon flux rates calculation is based on a multipole expansion.…”

Dose Rate Calculation in the Vicinity of the Tunisian Gamma Irradiation

“…The irradiator of the Tunisian National Center for Nuclear Sciences and Technologies (CNSTN) is designed for medical devices sterilisation and foodstuff preservation [6]. It is built of eight 60 Co pencils, each of 45 cm height and 1 cm diameter.…”

Comment on “Dose Mapping Using Multipole Moments”

“…In order to calculate the photon flux and the dose rate in the vicinity of the 60 Co gamma source presented below, the author has used the multipole expansion as function of r'/r, where r' is the vector position of an elementary source activity and r is the vector position of the dosimeter relative to the source [2]. In its work [3], the author has calculated the gamma flux rates in 36 points in the vicinity of the source.…”