open access

Vol 19, No 3 (2014)
Published online: 2014-05-01
Submitted: 2013-01-06
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Calibration of Ir high dose rate brachytherapy source using different calibration procedures

Shwetha Bondel, Manickham Ravikumar, Sanjay Sudhakar Supe, Buchuppudi Rekha Reddy
DOI: 10.1016/j.rpor.2013.07.014
·
Rep Pract Oncol Radiother 2014;19(3):151-156.

open access

Vol 19, No 3 (2014)
Published online: 2014-05-01
Submitted: 2013-01-06

Abstract

Aim

To calibrate Ir-192 high dose rate (HDR) brachytherapy source using different calibration methods and to determine the accuracy and suitability of each method for routine calibrations.

Background

The source calibration is an essential part of the quality assurance programme for dosimetry of brachytherapy sources. The clinical use of brachytherapy source requires an independent measurement of the air kerma strength according to the recommendations of medical physics societies.

Materials and methods

The Ir-192 HDR brachytherapy source from Gammamed plus machine (Varian Medical Systems, Palo Alto, CA) was calibrated using three different procedures, one using the well-type ionization chamber, second by the in-air calibration method and third using solid water phantoms. The reference air kerma rate (RAKR) of the source was determined using Deutsche Gesellschaft fur Medizinische Physik (DGMP) recommendations.

Results

The RAKR determined using different calibration methods are in good agreement with the manufacturer stated value. The mean percentage variations of 0.21, −0.94, −0.62 and 0.58 in RAKR values with respect to the manufacturer quoted values were observed with the well-type chamber, in-air calibration, cylindrical phantom and slab phantom measurements, respectively.

Conclusion

Measurements with a well-type chamber are relatively simple to perform. For in-air measurements, the indigenously designed calibration jig provides an accurate positioning of the source and chamber with minimum scatter contribution. The slab phantom system has an advantage that no additional phantom and chamber are required other than those used for external beam therapy dosimetry. All the methods of calibration discussed in this study are effective to be used for routine calibration purposes.

Abstract

Aim

To calibrate Ir-192 high dose rate (HDR) brachytherapy source using different calibration methods and to determine the accuracy and suitability of each method for routine calibrations.

Background

The source calibration is an essential part of the quality assurance programme for dosimetry of brachytherapy sources. The clinical use of brachytherapy source requires an independent measurement of the air kerma strength according to the recommendations of medical physics societies.

Materials and methods

The Ir-192 HDR brachytherapy source from Gammamed plus machine (Varian Medical Systems, Palo Alto, CA) was calibrated using three different procedures, one using the well-type ionization chamber, second by the in-air calibration method and third using solid water phantoms. The reference air kerma rate (RAKR) of the source was determined using Deutsche Gesellschaft fur Medizinische Physik (DGMP) recommendations.

Results

The RAKR determined using different calibration methods are in good agreement with the manufacturer stated value. The mean percentage variations of 0.21, −0.94, −0.62 and 0.58 in RAKR values with respect to the manufacturer quoted values were observed with the well-type chamber, in-air calibration, cylindrical phantom and slab phantom measurements, respectively.

Conclusion

Measurements with a well-type chamber are relatively simple to perform. For in-air measurements, the indigenously designed calibration jig provides an accurate positioning of the source and chamber with minimum scatter contribution. The slab phantom system has an advantage that no additional phantom and chamber are required other than those used for external beam therapy dosimetry. All the methods of calibration discussed in this study are effective to be used for routine calibration purposes.

Get Citation

Keywords

Well-type chamber; In-air calibration; Reference air kerma rate; High dose rate brachytherapy

About this article
Title

Calibration of Ir high dose rate brachytherapy source using different calibration procedures

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 19, No 3 (2014)

Pages

151-156

Published online

2014-05-01

DOI

10.1016/j.rpor.2013.07.014

Bibliographic record

Rep Pract Oncol Radiother 2014;19(3):151-156.

Keywords

Well-type chamber
In-air calibration
Reference air kerma rate
High dose rate brachytherapy

Authors

Shwetha Bondel
Manickham Ravikumar
Sanjay Sudhakar Supe
Buchuppudi Rekha Reddy

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