Experimental study of the influence of dental restorations on thermal and fast photo-neutron production in radiotherapy with a high-energy photon beam. (May 2019)

• Record Type: Journal Article
• Authors: Ghorbani, Mahdi; Azizi, Mona; Mowlavi, Ali Asghar; Azadegan, Behnam
• Is Part Of: Applied radiation and isotopes. Volume 147(2019:May)
• Page Start: 113
• Page End: 120
• Publication Date: 2019-05
• Subjects: Neutron contamination -- Thermal and fast-neutron equivalent dose -- Medical linear accelerator -- Dental restoration -- CR-39 detector; Radiology -- Periodicals; Radiation -- Industrial applications -- Periodicals; Nuclear chemistry -- Periodicals; Internet resource; Periodical; 660.298
• DOI: 10.1016/j.apradiso.2019.03.007
• Languages: English
• ISSNs: 0969-8043

Abstract

Abstract: In head and neck radiation therapy, the presence of dental restorations can increase unwanted neutron dose to the patient. This study aimed at the measurement of secondary neutron production induced by irradiation of a healthy tooth, Amalgam, Ni-Cr alloy and Ceramco with a photon beam generated in the treatment head of a Siemens Primus linac at a voltage of 15 MV. The irradiation field amounted to 10 × 10 cm 2 . The measurements of thermal and fast-neutron equivalent doses were performed by means of CR-39 detectors positioned in various depths of a Perspex (polymethyl methacrylate) phantom as at open field as at presence of corresponding dental restorations. The general trend of thermal neutron as well as fast-neutron equivalent dose behind the denture samples reveals their reduction with increasing depth. The maximum values of thermal-neutron dose related to Amalgam, Ceramco and Ni-Cr alloy amount to 1.45 mSv/100 MU, 1.38 mSv/100 MU and 1.32 mSv/100 MU, whereas the corresponding maximum values of fast-neutron dose at the depth of 1.8 cm amount to 0.19 mSv/100 MU, 1.04 mSv/100 MU and 0.97 mSv/100 MU, respectively. The present study investigates the neutron dose accompanied with radiotherapy. It is recommended that attempts have to be made to ensure that dental restorations are not in the path of the primary high-energy photon beam. Considering treatment planning, the guidelines of radiation protection should be improved. Highlights: Presence of dental restorations in path of photon beam in radiotherapy of head and neck cancer. Amalgam, Ni-Cr alloy, and Ceramco are the most common dental restoration in cancerous patients. Thermal and fast neutron production in radiotherapy with high energy photon due to their high density. Amalgam, Ceramco, and Ni-Cr alloy have the dominant contribution in the total neutron dose, respectively.