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Monte Carlo study on effective source to surface distance for electron beams from a mobile dedicated IORT accelerator

Published online by Cambridge University Press:  04 November 2016

Mir Rashid Hosseini Aghdam ,
Hamid Reza Baghani ,
Seyed Rabi Mahdavi ,
Seyed Mahmoud Reza Aghamiri  and
Mohammad Esmail Akbari
Mir Rashid Hosseini Aghdam
Affiliation:
Young Researchers Club, Abhar Branch, Islamic Azad University, Abhar, Iran Radiation Medicine Department, Shahid Beheshti University, Tehran, Iran
Hamid Reza Baghani
Affiliation:
Radiation Medicine Department, Shahid Beheshti University, Tehran, Iran
Seyed Rabi Mahdavi*
Affiliation:
Medical Physics Department, Iran University of Medical Sciences, Tehran, Iran
Seyed Mahmoud Reza Aghamiri
Affiliation:
Radiation Medicine Department, Shahid Beheshti University, Tehran, Iran
Mohammad Esmail Akbari
Affiliation:
Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
*
Correspondence to: Seyed R. Mahdavi, Medical Physics Department, Iran University of Medical Sciences, Tehran 14496141525, Iran. Tel: 982188622647. Fax: 982188622647. E-mail: srmahdavi@hotmail.com
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Abstract

Purpose

The effective source to surface distance (SSDeff) for different combinations of energy/applicator size of the electron beam produced by the light intraoperative accelerator, a mobile dedicated intraoperative radiotherapy accelerator, has been calculated in this study.

Methods

Both ionometric dosimetry and Monte Carlo (MC) simulation were followed to obtain the SSDeff for different combinations of electron energy/applicator size. Simulations were performed using Monte Carlo Nuclear Particles (MCNP) MC code. Measurements were performed by Advance Markus chamber and inside a polymethyl methacrylate slab phantom. Inverse square law method was employed to determine the SSDeff from acquired dosimetry data.

Result

With increasing the applicator diameter at a given energy, SSDeff is also increased. The same result is obtained with increasing the electron beam energy for a given applicator size. The results of MC-based SSDeff for 10 cm diameter reference applicator at different energies were in a good accordance with those obtained by ionometric dosimetry. The maximum and mean differences between the results were 1·1 and 0·6%, respectively.

Conclusions

The results of this study showed that SSDeff of intraoperative electron beam is highly dependent on the applicator size and is a mild function of electron beam energy. These facts are in accordance with those reported for conventional electron beam. The good agreement between the results of MC simulation and ionometric dosimetry confirms the application of MCNP code in modelling of intraoperative electron beam and obtaining the intended parameters.

Keywords

effective source to surface distance (SSDeff)ionometric dosimetryLIAC IOERT acceleratorMonte Carlo simulation
Type
Original Articles
Information
Journal of Radiotherapy in Practice , Volume 16 , Issue 1 , March 2017 , pp. 29 - 37
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Copyright
© Cambridge University Press 2016 

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