Akademik Veri Yönetim Sistemi
Turk Onkoloji Dergisi, cilt.38, sa.3, ss.264-269, 2023 (ESCI, Scopus, TRDizin)
OBJECTIVE Computed tomography images used in radiotherapy are automatically created by Treatment Planning Systems using the patient’s body contour. However, due to irregularities in the head-and-neck region, some corrections are required, especially for auricular contours. Since the beam entrances are at all an-gles, a change in the auricular contour may alter the beam’s entry angle and distance, which may cause changes in the target volume and surrounding critical structure doses in the volumetric arc technique (VMAT). We aimed to dosimetrically compare the treatment plans created with and without correction of auricular contours on the planning images. METHODS The data of 19 nasopharyngeal cancer patients treated using VMAT were evaluated. The VMAT treatment plans made in the Eclipse Treatment Planning System using the same optimization values were evaluated based on the ability to meet dose‐volume constraints. Using the Student’s t-test and Wilcoxon signed-rank test, comparisons were made of planning doses, planning target volumes (PTV), conform-ity index (CI), homogeneity index (HI), and critical organs involved. RESULTS We found a statistically significant difference between the corrected and non-corrected plans regarding maximum dose (Dmax), dose to 2% of PTV (D2), CI, and HI. When evaluated in terms of normal tissue doses, especially in patients with level 2 cervical lymph node metastases, particularly for the parotid mean dose, a statistically significant increase in the planning dose was observed when the auricular contour was corrected (p<0.001). CONCLUSION Thus, applying auricular contour correction on an individual patient basis seems appropriate, especially in the presence of target volumes with close localization.