open access

Vol 12, No 6 (2007)
Untitled
Published online: 2007-11-01
Submitted: 2007-04-27
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Reproducibility of tangential breast fields using online electronic portal images

Ramachandran Prabhakar, Goura K. Rath, Pramod K. Julka, Tharmar Ganesh, Rakesh C. Joshi
DOI: 10.1016/S1507-1367(10)60072-7
·
Rep Pract Oncol Radiother 2007;12(6):323-328.

open access

Vol 12, No 6 (2007)
Untitled
Published online: 2007-11-01
Submitted: 2007-04-27

Abstract

Background

Treatment verification and reproducibility plays a major role in radiotherapy to achieve better tumour control. Small uncertainties in daily repositioning of the patients and internal organ motion can lead to discrepancies between the planned and delivered radiation treatments. A factor that influences dose homogeneity and treatment volume is the accuracy of treatment setup. Small deviations in positioning the patient with regard to the beam setup could have a relatively significant impact on the treatment volume and it is imperative to control the setup error during radiotherapy. This study focuses on the importance of inter- and intra-fraction error in tangential breast radiotherapy with an electronic portal imaging device.

Aim

To study the variation in treatment setup due to intra-fraction and inter-fraction during tangential field breast irradiation.

Materials/Methods

Twelve patients of carcinoma breast were selected for this study and CT based planning was performed with simple tangential fields. The patients were treated on a 6MV linear accelerator equipped with an electronic portal imaging device (EPID). Portal images were acquired for both medial and lateral tangential fields for 10 fractions and intra- and inter-fraction studies were performed for all the patients. Parameters such as central lung distance (CLD), central beam edge to skin distance (CBESD), central irradiated width (CIW) and cranio-caudal distances (CCD) were measured on the acquired portal image.

Results

The average systematic differences observed for CLD, CBESD, CCD and CIW were 1.2mm, 2.8mm, 2.07mm and 3.30mm. For intra-fraction motion, the observed standard deviations for CLD, CBESD and CCD were 0.7mm, 0.73mm, and 1.36mm. Similarly the CLD, CBESD, CIW and CCD were analyzed for inter-fraction variation.

Conclusions

The online portal imaging device is an important tool for ensuring the proper delivery of planned dose. Our results suggest that intra-fraction motion of the breast has less impact on the treatment volume. Regular treatment verification between treatment fractions will help in reducing the normal tissue toxicity and ensures proper dose delivery to the tumour volume.

Abstract

Background

Treatment verification and reproducibility plays a major role in radiotherapy to achieve better tumour control. Small uncertainties in daily repositioning of the patients and internal organ motion can lead to discrepancies between the planned and delivered radiation treatments. A factor that influences dose homogeneity and treatment volume is the accuracy of treatment setup. Small deviations in positioning the patient with regard to the beam setup could have a relatively significant impact on the treatment volume and it is imperative to control the setup error during radiotherapy. This study focuses on the importance of inter- and intra-fraction error in tangential breast radiotherapy with an electronic portal imaging device.

Aim

To study the variation in treatment setup due to intra-fraction and inter-fraction during tangential field breast irradiation.

Materials/Methods

Twelve patients of carcinoma breast were selected for this study and CT based planning was performed with simple tangential fields. The patients were treated on a 6MV linear accelerator equipped with an electronic portal imaging device (EPID). Portal images were acquired for both medial and lateral tangential fields for 10 fractions and intra- and inter-fraction studies were performed for all the patients. Parameters such as central lung distance (CLD), central beam edge to skin distance (CBESD), central irradiated width (CIW) and cranio-caudal distances (CCD) were measured on the acquired portal image.

Results

The average systematic differences observed for CLD, CBESD, CCD and CIW were 1.2mm, 2.8mm, 2.07mm and 3.30mm. For intra-fraction motion, the observed standard deviations for CLD, CBESD and CCD were 0.7mm, 0.73mm, and 1.36mm. Similarly the CLD, CBESD, CIW and CCD were analyzed for inter-fraction variation.

Conclusions

The online portal imaging device is an important tool for ensuring the proper delivery of planned dose. Our results suggest that intra-fraction motion of the breast has less impact on the treatment volume. Regular treatment verification between treatment fractions will help in reducing the normal tissue toxicity and ensures proper dose delivery to the tumour volume.

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Keywords

breast cancer; tangential field radiotherapy; setup error; EPID

About this article
Title

Reproducibility of tangential breast fields using online electronic portal images

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 12, No 6 (2007)

Pages

323-328

Published online

2007-11-01

DOI

10.1016/S1507-1367(10)60072-7

Bibliographic record

Rep Pract Oncol Radiother 2007;12(6):323-328.

Keywords

breast cancer
tangential field radiotherapy
setup error
EPID

Authors

Ramachandran Prabhakar
Goura K. Rath
Pramod K. Julka
Tharmar Ganesh
Rakesh C. Joshi

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