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Dosimetric Comparison of Four Different Techniques for Supraclavicular Irradiation in 3D-conformal Radiotherapy of Breast Cancer

Firouzjah, Razzagh Abedi1; Banaei, Amin2,3; Farhood, Bagher4; Bakhshandeh, Mohsen5

doi: 10.1097/HP.0000000000000991
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This study aimed to compare and evaluated the dosimetric characteristics of esophagus, spinal cord, carotid artery, lungs, and brachial plexus in patients with breast cancer undergoing four various techniques of supraclavicular irradiation. By keeping unchanged the breast tangential radiotherapy fields, four different treatment field arrangements were created to irradiate the supraclavicular region as follows: (1) four field (4F; 1 anterior-posterior and 1 posterior-anterior), (2) six field (6F; 2 anterior-posterior and 2 posterior-anterior), (3) five field-1 (5F-1; 2 anterior-posterior and 1 posterior-anterior), and (4) five field-2 (5F-2; 1 anterior-posterior and 2 posterior-anterior). Then, the dosimetric parameters for the above-mentioned organs were evaluated. The mean dose (Dmean) of the esophagus had significant difference between 6F and 5F-2 techniques. For the spinal cord, the Dmean dosimetric parameter demonstrated significant difference between the 4F and 6F techniques, and between the 4F and 5F-1 techniques, with lower values for the 4F technique. There was no significant difference between the different irradiation techniques in all the dosimetric parameters for the carotid artery. The Dmean of the left lung significantly differed between the 4F and 5F-2 techniques, with lower values for the 5F-2 technique. Furthermore, the V20Gy dosimetric parameter had significant difference between the 4F and 6F, and also 4F and 5F-2, techniques with lower values for 5F-2. The maximum dose (Dmax) of the brachial plexus showed significant difference between the two techniques of 5F. The V45Gy dosimetric parameter of the brachial plexus revealed significant difference between the 4F and 6F techniques, and also between the 4F and 5F-1 techniques, with lower values for 5F-1. In general, these techniques had similar dosimetric results, with little differences. The dosimetric parameters for the esophagus and lung showed better results with the 5F-2 technique in comparison with other techniques. Dosimetric results for the brachial plexus and spinal cord improved with the 5F-1 and 4F techniques, respectively, against other techniques. Dose distribution for the carotid artery did not differ in the four irradiation techniques.

1Department of Medical Physics, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran;

2Department of Radiology, Faculty of Paramedical Sciences, AJA University of Medical Sciences, Tehran, Iran;

3Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran;

4Department of Medical Physics and Radiology, Faculty of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran;

5Radiation Technology Department, Allied Medical Sciences Faculty, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

The authors declare no conflicts of interest.

For correspondence contact Mohsen Bakhshandeh, Radiation Technology Department, Allied Medical Sciences Faculty, Shahid Beheshti University of Medical Sciences, Postal code 1985717443, Tehran, Iran, or email at Mbakshandeh@sbmu.ac.ir.

(Manuscript accepted 29 August 2018)

© 2019 by the Health Physics Society