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. 2013 Apr;3(2):107-16.

Optimizing of the Tangential Technique and Supraclavicular Fields in 3 Dimensional Conformal Radiation Therapy for Breast Cancer

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Free PMC article

Optimizing of the Tangential Technique and Supraclavicular Fields in 3 Dimensional Conformal Radiation Therapy for Breast Cancer

Keyvan Jabbari et al. J Med Signals Sens. .
Free PMC article

Abstract

Radiotherapy plays an essential role in the management of breast cancer. Three-dimensional conformal radiation therapy (3D-CRT) is applied based on 3D image information of anatomy of patients. In 3D-CRT for breast cancer one of the common techniques is tangential technique. In this project, various parameters of tangential and supraclavicular fields are optimized. This project has been done on computed tomography images of 100 patients in Isfahan Milad Hospital. All patients have been simulated and all the important organs have been contoured by radiation oncologist. Two techniques in supraclavicular region are evaluated including: 1-A single field (Anterior Posterior [AP]) with a dose of 200 cGy per fraction with 6 MV energy. This is a common technique. 2-Two parallel opposed fields (AP-Posterior Anterior [PA]). The dose of AP was 150 cGy with 6 MV energy and PA 50 cGy with 18 MV. In the second part of the project, the tangential fields has been optimized with change of normalization point in five points: (1) Isocenter (Confluence of rotation gantry axis and collimator axis) (2) Middle of thickest part of breast or middle of inter field distance (IFD) (3) Border between the lung and chest wall (4) Physician's choice (5) Between IFD and isocenter. Dose distributions have been compared for all patients in different methods of supraclavicular and tangential field. In parallel opposed fields average lung dose was 4% more than a single field and the maximum received heart dose was 21.5% less than a single field. The average dose of planning tumor volume (PTV) in method 2 is 2% more than method 1. In general AP-PA method because of a better coverage of PTV is suggested. In optimization of the tangential field all methods have similar coverage of PTV. Each method has spatial advantages and disadvantages. If it is important for the physician to reduce the dose received by the lung and heart, fifth method is suggested since in this method average and maximum received dose to heart and lung have been reduced few percent in comparison to other methods. If a better coverage of PTV is important for the physician second method can be an optimized method. In this method, average and maximum received dose to PTV have been increased few percent in comparisons of physician's choice method and three other methods. In optimizing of supraclavicular field AP-PA method due to better coverage of PTV is suggested. In optimizing of tangential all methods are similar. Each method has special advantages and disadvantages. The physicians can change the depth of the normalization point in the breast to get the desired average dose.

Keywords: Breast cancer; radiation therapy; treatment planning.

Conflict of interest statement

Conflict of Interest: None declared

Figures

Figure 1
Figure 1
A tangential field in radiotherapy for breast with 15° wedge
Figure 2
Figure 2
The tangential and supraclavicular areas in radiotherapy for breast
Figure 3
Figure 3
A single field technique (Anterior Posterior) irradiated to gross tumor volume
Figure 4
Figure 4
Two parallel opposed fields (Anterior Posterior-Posterior Anterior). Both fields are angled 15° to avoid the irradiation of the spine
Figure 5
Figure 5
The location of the normalization points P1 is isocenter of the beams. 3 other points are located in the larger depths
Figure 6
Figure 6
The location of the normalization points
Figure 7
Figure 7
Dose distribution in a single field technique
Figure 8
Figure 8
Dose distribution in Anterior Posterior-Posterior Anterior technique
Figure 9
Figure 9
Graph of average received supraclavicular dose in planning tumor volume
Figure 10
Figure 10
Graph of maximum received heart dose
Figure 11
Figure 11
Graph of average received lung dose
Figure 12
Figure 12
Graph of average received spine dose
Figure 13
Figure 13
Graph of maximum received spine dose
Figure 14
Figure 14
Graph of average received skin dose
Figure 15
Figure 15
Graph of maximum received skin dose
Figure 16
Figure 16
The average received breast dose
Figure 17
Figure 17
The average received heart dose
Figure 18
Figure 18
The maximum received heart dose
Figure 19
Figure 19
The average received lung dose
Figure 20
Figure 20
The maximum received lung dose

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