الفهرس 
ContentsOnly 14 pages are availabe for public view
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Abstract
Breast conserving therapy (BCT) became an accepted option for the treatment of most stage I or II invasive breast cancer in women instead of mastectomy. An additional boost dose of “10 to 16 Gy” delivered to the tumor bed has shown an additional gain in decreasing local recurrence in patients. Up till now, it is unclear which technique is recommended to deliver the boost dose to the tumor bed. So investigations are needed to describe the differences between them and to modify a new techniques to irradiate breast with minimal side effects on organs at risk “OARs”. The aim of this work is to study the biophysical effects of radiation on breast cancer treated with 3 different boost dose delivery techniques, by which the boost dose is delivered to the tumor bed in both left and right breast, aiming to present the best technique of treatment for breast cancer patients In this work, the breast cancer computed tomography (CT) scans were selected for early left and right breast cancer patients. three different treatment plans are made for each patient CT using three different irradiation techniques to deliver a prescribed boost dose of “10 Gy” in “5 fractions” to the boost PTV, In the first technique two tangential photon beams were used, in the second technique two oblique photon beams are used and in the third technique a single electron beam was used. The comparative analyses between the three techniques were performed by comparing the boost PTV- dose volume histograms (DVHs), the ipsilateral breast DVHs, the ipsilateral lung DVHs and the heart DVHs of the three techniques for each patient. Furthermore the dose that covering 100% , 95% of the volume (D100% , D95%) and V95% of the boost PTV of all techniques, were calculated for each patient to investigate the dose coverage of the target. Results showed that there were variations of the dose received by tumor bed, ipsilateral breast and OARs, in left breast cases, depending on the technique used and the target location and size. A decrease of D100% than 90% of the prescribed dose was observed with the 2nd technique for patients 1, 6 and 7, and was observed with the 1st technique for patient 6, and observed with patient 8 with the 3rd technique. A reduction of left breast dose was observed when the 3rd technique was use in comparison with the 1st and the 2nd techniques for patients 1, 2, 3, 4 and 5. An increase of left lung dose was observed with the 3rd technique for patients 2 and 7, also was observed with 1st technique in patient 1. Also there were variations of the dose received by tumor bed, right breast and OARs, in right breast cases. A decrease of D100% than 90% of the prescribed dose was observed with the 3rd technique for patients 18 and 19 and was observed with the 2nd technique for patient 15. A reduction of right breast dose was observed when the 3rd technique was use in comparison with the 1st and the 2nd techniques for patients 11, 12, 13, 14, 16 and 18. Also reduction of right breast was observed when the 2nd technique used in comparison with 1st technique. An increase of lung dose was observed with the 3rd technique for patients 11, 12, 15 and 16, also was observed with 2nd technique in patient 13, 15 and 17. A decrease of right lung dose was observed with the 1st technique for patients 12, 14, 15, 16, 17, 18 and 19. An individualized treatment and several plans using different irradiation techniques should be developed for each patient individually to reach the most appropriate boost PTV dose coverage with minimal “OARs’ dose.