Determination of the neutron spectra around an 18MV medical LINAC with a passive Bonner sphere spectrometer based on gold foils and TLD pairs

Photoneutron Flux Measurement via Neutron Activation Analysis in a Radiotherapy Bunker with an 18 MV Linear Accelerator

“…After the measurement, the maximum neutron flux was observed at 1 cm away from the center and at SSD 100 cm flux was 48% of the maximum flux. At the maze entry, the flux was 15% of the maximum flux [20]. The results were given in terms of dose values so it would be appropriate to compare the results relatively with our study.…”

Undesirable Radioisotopes Induced by Therapeutic Beams from Medical Linear Accelerators

“…Electrons from the  -decay of this radioisotope have R m,air = 400 cm and R m,bt = 0.5 cm. The neutrons from (,n) reactions taking place in the components of the medical accelerator head have a broad energy spectrum inside the radiotherapy facility (see [17,18] The scheme of disintegration of the metastable 204m Pb state is presented in Figure 5.5. In the previous paragraph the 209 Pb radioisotope was mentioned to be a result of the simple capture reaction.…”

Design and experimental validation of a Bonner Sphere Spectrometer based on Dysprosium activation foils

“…Each sphere was irradiated for 2 h, and the Dy foils were counted for 1 h. The corresponding counting uncertainties were lower than AE1%. These short times, made possible by the high cross section and short half life of the Dysprosium, should be compared with those of a previously studied gold foils-based BSS (Bedogni et al, 2008), requiring irradiation/counting times of about 8e10 h. The possibility to achieve large activations in short irradiation would constitute a major advantage in workplace measurements, especially in those facilities that are used for radiotherapy or industrial processes.…”

“…Whilst TLDs are in general more sensitive, gold foils are most suited for workplaces with high photon component because of their insensitivity to photons. Moreover, when compared in the same workplace, the TLD-based BSS lead to higher uncertainties if compared with the gold foils-based BSS (Esposito et al, 2008). The main limitation of gold foils-based BSS is the low sensitivity, mainly due to the long half live of the activation product, 198 Au (T 1/2 ¼ 2.696 d).…”