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Title: Radiation protection measurements around a 12 MeV mobile dedicated IORT accelerator

Abstract

Purpose: The aim of this study is to investigate radioprotection issues that must be addressed when dedicated accelerators for intraoperative radiotherapy (IORT) are used in operating rooms. Recently, a new version of a mobile IORT accelerator (LIAC Sordina SpA, Italy) with 12 MeV electron beam has been implemented. This energy is necessary in some specific pathology treatments to allow a better coverage of thick lesions. At an electron energy of 10 MeV, leakage and scattered x-ray radiation (stray radiation) coming from the accelerator device and patient must be considered. If the energy is greater than 10 MeV, the x-ray component will increase; however, the most meaningful change should be the addition of neutron background. Therefore, radiation exposure of personnel during the IORT procedure needs to be carefully evaluated. Methods: In this study, stray x-ray radiation was measured and characterized in a series of spherical projections by means of an ion chamber survey meter. To simulate the patient during all measurements, a polymethylmethacrylate (PMMA) slab phantom with volume 30x30x15 cm{sup 3} and density 1.19 g/cm{sup 3} was used. The PMMA phantom was placed along the central axis of the beam in order to absorb the electron beams and the tenth valuemore » layer (TVL) and half value layer (HVL) of scattered radiation (at 0 deg., 90 deg., and 180 deg. scattering angles) were also measured at 1 m of distance from the phantom center. Neutron measurements were performed using passive bubble dosimeters and a neutron probe, specially designed to evaluate ambient dose equivalent H{sup *}(10). Results: The x-ray equivalent dose measured at 1 m along the beam axis at 12 MeV was 260 {mu}Sv/Gy. The value measured at 1 m at 90 deg. scattering angle was 25 {mu}Sv/Gy. The HVL and TVL values were 1.1 and 3.5 cm of lead at 0 deg., and 0.4 and 1 cm at 90 deg., respectively. The highest equivalent dose of fast neutrons was found to be at the surface of the phantom on the central beam axis (2.9{+-}0.6 {mu}Sv/Gy), while a lower value was observed below the phantom (1.6{+-}0.3 {mu}Sv/Gy). The neutron dose equivalent at 90 deg. scattering angle and on the floor plane on the beam axis below the beam stopper was negligible. Conclusions: Our data confirm that neutron exposure levels around the new dedicated IORT accelerator are very low. Mobile shielding panels can be used to reduce x-ray levels to below regulatory levels without necessarily providing permanent shielding in the operating room.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. Laboratory of Medical Physics, Istituto Regina Elena, via Elio Chianesi 53, 00144 Rome (Italy)
Publication Date:
OSTI Identifier:
22098508
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 37; Journal Issue: 3; Other Information: (c) 2010 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; DOSE EQUIVALENTS; DOSEMETERS; DOSIMETRY; ELECTRON BEAMS; FAST NEUTRONS; IONIZATION CHAMBERS; LINEAR ACCELERATORS; MEDICAL PERSONNEL; NEUTRON BEAMS; PATHOLOGY; PHANTOMS; PMMA; RADIATION PROTECTION; RADIOTHERAPY; SHIELDING; STRAY RADIATION; X RADIATION

Citation Formats

Soriani, Antonella, Felici, Giuseppe, Fantini, Mario, Paolucci, Massimiliano, Borla, Oscar, Evangelisti, Giovanna, Benassi, Marcello, Strigari, Lidia, Sordina SpA Technical Division, via Calanna 25, 00126 Rome, Department of Medical Physics, ASL n.3, Umbria V. Arcamone 1, 06034 Foligno, I.N.F.N. sez. Torino, Via Pietro Giuria 1, 10125 Torino, and Laboratory of Medical Physics, Istituto Regina Elena, via Elio Chianesi 53, 00144 Roma. Radiation protection measurements around a 12 MeV mobile dedicated IORT accelerator. United States: N. p., 2010. Web. doi:10.1118/1.3298012.
Soriani, Antonella, Felici, Giuseppe, Fantini, Mario, Paolucci, Massimiliano, Borla, Oscar, Evangelisti, Giovanna, Benassi, Marcello, Strigari, Lidia, Sordina SpA Technical Division, via Calanna 25, 00126 Rome, Department of Medical Physics, ASL n.3, Umbria V. Arcamone 1, 06034 Foligno, I.N.F.N. sez. Torino, Via Pietro Giuria 1, 10125 Torino, & Laboratory of Medical Physics, Istituto Regina Elena, via Elio Chianesi 53, 00144 Roma. Radiation protection measurements around a 12 MeV mobile dedicated IORT accelerator. United States. https://doi.org/10.1118/1.3298012
Soriani, Antonella, Felici, Giuseppe, Fantini, Mario, Paolucci, Massimiliano, Borla, Oscar, Evangelisti, Giovanna, Benassi, Marcello, Strigari, Lidia, Sordina SpA Technical Division, via Calanna 25, 00126 Rome, Department of Medical Physics, ASL n.3, Umbria V. Arcamone 1, 06034 Foligno, I.N.F.N. sez. Torino, Via Pietro Giuria 1, 10125 Torino, and Laboratory of Medical Physics, Istituto Regina Elena, via Elio Chianesi 53, 00144 Roma. 2010. "Radiation protection measurements around a 12 MeV mobile dedicated IORT accelerator". United States. https://doi.org/10.1118/1.3298012.
@article{osti_22098508,
title = {Radiation protection measurements around a 12 MeV mobile dedicated IORT accelerator},
author = {Soriani, Antonella and Felici, Giuseppe and Fantini, Mario and Paolucci, Massimiliano and Borla, Oscar and Evangelisti, Giovanna and Benassi, Marcello and Strigari, Lidia and Sordina SpA Technical Division, via Calanna 25, 00126 Rome and Department of Medical Physics, ASL n.3, Umbria V. Arcamone 1, 06034 Foligno and I.N.F.N. sez. Torino, Via Pietro Giuria 1, 10125 Torino and Laboratory of Medical Physics, Istituto Regina Elena, via Elio Chianesi 53, 00144 Roma},
abstractNote = {Purpose: The aim of this study is to investigate radioprotection issues that must be addressed when dedicated accelerators for intraoperative radiotherapy (IORT) are used in operating rooms. Recently, a new version of a mobile IORT accelerator (LIAC Sordina SpA, Italy) with 12 MeV electron beam has been implemented. This energy is necessary in some specific pathology treatments to allow a better coverage of thick lesions. At an electron energy of 10 MeV, leakage and scattered x-ray radiation (stray radiation) coming from the accelerator device and patient must be considered. If the energy is greater than 10 MeV, the x-ray component will increase; however, the most meaningful change should be the addition of neutron background. Therefore, radiation exposure of personnel during the IORT procedure needs to be carefully evaluated. Methods: In this study, stray x-ray radiation was measured and characterized in a series of spherical projections by means of an ion chamber survey meter. To simulate the patient during all measurements, a polymethylmethacrylate (PMMA) slab phantom with volume 30x30x15 cm{sup 3} and density 1.19 g/cm{sup 3} was used. The PMMA phantom was placed along the central axis of the beam in order to absorb the electron beams and the tenth value layer (TVL) and half value layer (HVL) of scattered radiation (at 0 deg., 90 deg., and 180 deg. scattering angles) were also measured at 1 m of distance from the phantom center. Neutron measurements were performed using passive bubble dosimeters and a neutron probe, specially designed to evaluate ambient dose equivalent H{sup *}(10). Results: The x-ray equivalent dose measured at 1 m along the beam axis at 12 MeV was 260 {mu}Sv/Gy. The value measured at 1 m at 90 deg. scattering angle was 25 {mu}Sv/Gy. The HVL and TVL values were 1.1 and 3.5 cm of lead at 0 deg., and 0.4 and 1 cm at 90 deg., respectively. The highest equivalent dose of fast neutrons was found to be at the surface of the phantom on the central beam axis (2.9{+-}0.6 {mu}Sv/Gy), while a lower value was observed below the phantom (1.6{+-}0.3 {mu}Sv/Gy). The neutron dose equivalent at 90 deg. scattering angle and on the floor plane on the beam axis below the beam stopper was negligible. Conclusions: Our data confirm that neutron exposure levels around the new dedicated IORT accelerator are very low. Mobile shielding panels can be used to reduce x-ray levels to below regulatory levels without necessarily providing permanent shielding in the operating room.},
doi = {10.1118/1.3298012},
url = {https://www.osti.gov/biblio/22098508}, journal = {Medical Physics},
issn = {0094-2405},
number = 3,
volume = 37,
place = {United States},
year = {Mon Mar 15 00:00:00 EDT 2010},
month = {Mon Mar 15 00:00:00 EDT 2010}
}