open access

Vol 14, No 5 (2009)
Untitled
Published online: 2009-09-01
Submitted: 2009-07-07
Get Citation

Comparison of peripheral dose measurements using Ionization chamber and MOSFET detector

Gopiraj ANNAMALAI, Ramasubramanian VELAYUDHAM
DOI: 10.1016/S1507-1367(10)60033-8
·
Rep Pract Oncol Radiother 2009;14(5):176-183.

open access

Vol 14, No 5 (2009)
Untitled
Published online: 2009-09-01
Submitted: 2009-07-07

Abstract

Background

In radiation therapy, the peripheral dose (PD) – the dose outside the geometric boundaries of the radiation field – is of clinical importance. A metal oxide semiconductor field effect transistor (MOSFET) detector is used to estimate the peripheral dose.

Aim

The aim of this study is to investigate the ability of a MOSFET dosimetry system to accurately measure doses in peripheral regions of high energy X-ray beams.

Materials & Methods

The accuracy of the MOSFET system is evaluated by comparing peripheral region dose measurement with the results of standard ionization chamber measurements. Furthermore, the measurement of PD using a MOSFET detector helps us to keep the tolerance dose of any critical organ closer to the treatment field within the acceptable limits. The measurements were carried out using a 0.6 cc Farmer type ionization chamber and MOSFET 20 dosimetry system for field sizes ranging from 5 × 5 cm2 to 20 × 20 cm2 at three depths of 1.5 cm, 5 cm and 10 cm in a blue water phantom. PD were measured at distances varying from 1 cm to 30 cm from the field edges along the x axis for the open fields, with collimator rotation and with beam modifiers like 15 degree, 30 degree and 45 degree wedges.

Results

The results show a good agreement of measured dose by both methods for various field sizes, collimator rotation and wedges.

Conclusion

The MOSFET detector has a compact construction, provides instant readout, is of minimal weight and can be used on any surface.

Abstract

Background

In radiation therapy, the peripheral dose (PD) – the dose outside the geometric boundaries of the radiation field – is of clinical importance. A metal oxide semiconductor field effect transistor (MOSFET) detector is used to estimate the peripheral dose.

Aim

The aim of this study is to investigate the ability of a MOSFET dosimetry system to accurately measure doses in peripheral regions of high energy X-ray beams.

Materials & Methods

The accuracy of the MOSFET system is evaluated by comparing peripheral region dose measurement with the results of standard ionization chamber measurements. Furthermore, the measurement of PD using a MOSFET detector helps us to keep the tolerance dose of any critical organ closer to the treatment field within the acceptable limits. The measurements were carried out using a 0.6 cc Farmer type ionization chamber and MOSFET 20 dosimetry system for field sizes ranging from 5 × 5 cm2 to 20 × 20 cm2 at three depths of 1.5 cm, 5 cm and 10 cm in a blue water phantom. PD were measured at distances varying from 1 cm to 30 cm from the field edges along the x axis for the open fields, with collimator rotation and with beam modifiers like 15 degree, 30 degree and 45 degree wedges.

Results

The results show a good agreement of measured dose by both methods for various field sizes, collimator rotation and wedges.

Conclusion

The MOSFET detector has a compact construction, provides instant readout, is of minimal weight and can be used on any surface.

Get Citation

Keywords

peripheral dose; MOSFET; radiation dosimetry

About this article
Title

Comparison of peripheral dose measurements using Ionization chamber and MOSFET detector

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 14, No 5 (2009)

Pages

176-183

Published online

2009-09-01

DOI

10.1016/S1507-1367(10)60033-8

Bibliographic record

Rep Pract Oncol Radiother 2009;14(5):176-183.

Keywords

peripheral dose
MOSFET
radiation dosimetry

Authors

Gopiraj ANNAMALAI
Ramasubramanian VELAYUDHAM

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: journals@viamedica.pl