engleski

Dose distribution analysis of three different radiotherapy techniques for a patient with left-sided breast cancer

In order to avoid possible acute and chronic toxicities of breast cancer radiotherapy treatment, appropriate techniques should obtain homogenous dose distribution to the breast and spare organs at risk. The aim of this study was to compare three different radiotherapy techniques for a patient with left-sided breast cancer. Clinical target volume (CTV)-breast, and organs at risk-lung, heart and contralateral breast were delineated on CT slices during radiotherapy planning for the patient after conserving breast surgery. Planning system CMS XiO 4.3.1.and Siemens Oncor linear accelerator with MLC and 6 MV energy were used. Three different radiotherapy techniques were compared: a plan with two tangential fields, and two plans for conformal « field in field» technique: a plan with four fields and with five fields, respectively. Posterior fifth field was added to the four „ field in field“ technique. Dose-volume histograms (DVH), and homogeneity index (HI) were compared. For this patient with wide tangential fields separation, where the maximal distance between medial and lateral PTV points was 23 cm, two tangential fields plan resulted in significant nonhomogeneity in PTV – HI was 0.84. The plan with four fields resulted in homogeneity index 0.88, while the best homogeneity was achieved by the five-field technique (HI -0.92). Doses to the organs at risk were lower in the five-field technique as compared to two tangential and four-field technique. By the five-field conformal breast irradiation technique it was possible to obtain dose homogeneity, to follow DVH constrains and to protect normal tissues.

breast cancer; radiotherapy; dose distribution

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