title: Measurement of eye lens dose for Varian On-Board Imaging with different cone-beam computed tomography acquisition techniques.
abstract: The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT) acquisition protocols of Varian's On-Board Imaging (OBI) system using optically stimulated luminescence dosimeter (OSLD) and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was placed on the patient between the eyebrows of both eyes in line of nose during CBCT image acquisition to measure eye lens doses. The eye lens dose measurements were carried out for three different cone-beam acquisition protocols (standard dose head, low-dose head [LDH], and high-quality head [HQH]) of Varian OBI. Measured doses were correlated with patient geometry and distance between isocenter and eye lens. Measured eye lens doses for standard head and HQH protocols were in the range of 1.8-3.2 mGy and 4.5-9.9 mGy, respectively. However, the measured eye lens dose for the LDH protocol was in the range of 0.3-0.7 mGy. The measured data indicate that eye lens dose to patient depends on the selected imaging protocol. It was also observed that eye lens dose does not depend on patient geometry but strongly depends on distance between eye lens and treatment field isocenter. However, undoubted advantages of imaging system should not be counterbalanced by inappropriate selection of imaging protocol, especially for very intense imaging protocol.
authors.affiliation: Department of Radiation Oncology, P. D. Hinduja National Hospital and MRC, Mumbai, Maharashtra, India.
authors.forename: Sudesh
authors.initials: S
authors.lastname: Deshpande
authors.affiliation: Department of Electronics, Brijlal Biyani College, Amravati, Maharashtra, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Dhote
authors.affiliation: Department of Radiation Oncology, Holy Spirit Hospital, Mumbai, Maharashtra, India.
authors.forename: Kalpna
authors.initials: K
authors.lastname: Thakur
authors.affiliation: Department of Radiation Oncology, Holy Spirit Hospital, Mumbai, Maharashtra, India.
authors.forename: Amol
authors.initials: A
authors.lastname: Pawar
authors.affiliation: Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India.
authors.forename: Munish
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India.
authors.forename: M S
authors.initials: MS
authors.lastname: Kulkarni
authors.affiliation: Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India.
authors.forename: S D
authors.initials: SD
authors.lastname: Sharma
authors.affiliation: Department of Radiation Oncology, P. D. Hinduja National Hospital and MRC, Mumbai, Maharashtra, India.
authors.forename: V
authors.initials: V
authors.lastname: Kannan
keywords: Eye lens dose; Varian cone-beam computed tomography; optically stimulated luminescence dosimeter