Measurement of Photo-Neutron Dose from an 18-MV Medical Linac Using a Foil Activation Method in View of Radiation Protection of Patients
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- 作者：Haluk Yü ; cel<sup>asup><sup> ; sup><sup>haluk.yucel@ankara.edu.tr" class="auth_mail" title="E-mail the corresponding authorsup> ; İbrahim Ç ; obanbaş<sup>bsup> ; Asuman Kolbaşı<sup>asup> ; Alptuğ Ö ; zer Yü ; ksel<sup>asup> ; Vildan Kaya<sup>bsup>
- 关键词：Dose ; Foil activation ; Neutron ; Patient ; Radiotherapy ; Radiation protection
- 刊名：Nuclear Engineering and Technology
- 出版年：2016
- 出版时间：April 2016
- 年：2016
- 卷：48
- 期：2
- 页码：525-532
- 全文大小：543 K
文摘
High-energy linear accelerators are increasingly used in the medical field. However, the unwanted photo-neutrons can also be contributed to the dose delivered to the patients during their treatments. In this study, neutron fluxes were measured in a solid water phantom placed at the isocenter 1-m distance from the head of an 18-MV linac using the foil activation method. The produced activities were measured with a calibrated well-type Ge detector. From the measured fluxes, the total neutron fluence was found to be (1.17 ± 0.06) × 10<sup>7sup> n/cm<sup>2sup> per Gy at the phantom surface in a 20 × 20 cm<sup>2sup> X-ray field size. The maximum photo-neutron dose was measured to be 0.67 ± 0.04 mSv/Gy at d<sub>maxsub> = 5 cm depth in the phantom at isocenter. The present results are compared with those obtained for different field sizes of 10 × 10cm<sup>2sup>, 15 × 15cm<sup>2sup>, and 20 × 20cm<sup>2sup> from 10-, 15-, and 18-MV linacs. Additionally, ambient neutron dose equivalents were determined at different locations in the room and they were found to be negligibly low. The results indicate that the photo-neutron dose at the patient position is not a negligible fraction of the therapeutic photon dose. Thus, there is a need for reduction of the contaminated neutron dose by taking some additional measures, for instance, neutron absorbing-protective materials might be used as aprons during the treatment.