Evaluation of photoneutron dose equivalent in 10 MV and 15 MV beams for wedge and open fields in the Elekta Versa HD linac

• Published in: Applied radiation and isotopes 2022-10, Vol.188, p.110363-110363, Article 110363
• Main Authors: Khilafath, Hajee Reyaz Ali Sahib, Ganesan, Bharanidharan, Sekar, Nandakumar, Mohapatra, Dinakrushna, Mahadevan, Pramod, Vellingiri, Jayaprakash, Prakasarao, Aruna, Singaravelu, Ganesan
• Format: Article
• Language: English
• Subjects: Bubble detector; High atomic material; Neutron contamination; Photoneutron dose equivalent; Versa HD™ linac; Wedge filter
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2022.110363

In a high-energy medical linear accelerator (linac), if the interaction of photon energy is higher than the neutron binding energy of high atomic material, it emits a neutron field through a photonuclear reaction. The objective of this current study is to measure the photoneutron dose equivalent produces in a motorized wedge field and open field of 10 MV and 15 MV photon beams in Elekta Versa HD™ linac. The PNDE values were recorded at various positions along the patient plane using the Bubble Detector-Personal Neutron Dosimeter (BD-PND). The results revealed that the PNDE values are higher in 20 × 20 cm2 than 10 × 10 cm2 field sizes for both the 60° wedge and open fields of 10 MV and 15 MV beams. In addition, the 60° wedge fields generate higher photoneutron contamination when compared with the 45°, 30° wedge fields and open field sizes. Hence, on average PNDE values produced by the 15 MV beam were higher by a factor of 1.98 and 2.11 times for open and 60° wedge fields than the 10 MV beam, respectively. •The effect of wedge and open field on photoneutron production in 10 MV and 15 MV beams was measured using Bubble Detector.•Neutrons are generated through photonuclear reactions with high atomic material.•At in-fields, the PNDE values were higher for larger field sizes for both wedge and open fields.•The universal wedge field yields higher photoneutron contamination than the open field.•The 10 MV beam produces a lesser photoneutron dose equivalent than the 15 MV beam.