open access

Vol 15, No 5 (2010)
Published online: 2010-09-01
Submitted: 2010-08-09
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Verification in the water phantom of the irradiation time calculation done by the algorithm used in intraoperative radiotherapy

Maria Słyk, Marcin Litoborski
DOI: 10.1016/j.rpor.2010.08.007
·
Rep Pract Oncol Radiother 2010;15(5):132-137.

open access

Vol 15, No 5 (2010)
Published online: 2010-09-01
Submitted: 2010-08-09

Abstract

Aim

The investigation of the irradiation time calculation accuracy of the GGPB algorithm used for IORT.

Background

Conventionally, breast conserving therapy consists of breast conserving surgery followed by postoperative whole breast irradiation and boost. The use of intraoperative radiotherapy (IORT) enables the boost to be delivered already during the surgery. In this case, the treatment dose for IORT can be calculated by use of General Gaussian Pencil Beam (GGPB) algorithm, which is implemented in TPS Eclipse.

Materials and methods

PDDs and OFs for electron beams from Mobetron and all available applicators were measured in order to configure the GGPB algorithm. Afterwards, the irradiation times for the prescribed dose of 3[[ce:hsp sp="0.25"/]]Gy were calculated by means of it. The results of calculations were verified in the water phantom using the Marcus ionization chamber.

Results

The results differed between energies. For 6[[ce:hsp sp="0.25"/]]MeV the irradiation times calculated by the GGPB algorithm were correct, for the energy of 9[[ce:hsp sp="0.25"/]]MeV they were too small and for the energy of 4[[ce:hsp sp="0.25"/]]MeV they were too large for applicators with smaller diameters, while acceptable for the remaining ones.

Conclusion

The GGPB algorithm can be used in intraoperative radiotherapy for energy and applicator sets for which no significant difference between the measured and the prescribed dose was obtained. For the rest of energy-applicator sets the configuration should be verified and possibly repeated.

Abstract

Aim

The investigation of the irradiation time calculation accuracy of the GGPB algorithm used for IORT.

Background

Conventionally, breast conserving therapy consists of breast conserving surgery followed by postoperative whole breast irradiation and boost. The use of intraoperative radiotherapy (IORT) enables the boost to be delivered already during the surgery. In this case, the treatment dose for IORT can be calculated by use of General Gaussian Pencil Beam (GGPB) algorithm, which is implemented in TPS Eclipse.

Materials and methods

PDDs and OFs for electron beams from Mobetron and all available applicators were measured in order to configure the GGPB algorithm. Afterwards, the irradiation times for the prescribed dose of 3[[ce:hsp sp="0.25"/]]Gy were calculated by means of it. The results of calculations were verified in the water phantom using the Marcus ionization chamber.

Results

The results differed between energies. For 6[[ce:hsp sp="0.25"/]]MeV the irradiation times calculated by the GGPB algorithm were correct, for the energy of 9[[ce:hsp sp="0.25"/]]MeV they were too small and for the energy of 4[[ce:hsp sp="0.25"/]]MeV they were too large for applicators with smaller diameters, while acceptable for the remaining ones.

Conclusion

The GGPB algorithm can be used in intraoperative radiotherapy for energy and applicator sets for which no significant difference between the measured and the prescribed dose was obtained. For the rest of energy-applicator sets the configuration should be verified and possibly repeated.

Get Citation

Keywords

GGPB algorithm; Algorithm configuration; Algorithm verification; IORT

About this article
Title

Verification in the water phantom of the irradiation time calculation done by the algorithm used in intraoperative radiotherapy

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 15, No 5 (2010)

Pages

132-137

Published online

2010-09-01

DOI

10.1016/j.rpor.2010.08.007

Bibliographic record

Rep Pract Oncol Radiother 2010;15(5):132-137.

Keywords

GGPB algorithm
Algorithm configuration
Algorithm verification
IORT

Authors

Maria Słyk
Marcin Litoborski

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