Search

OBJECTIVE To compare the dosimetric criteria of intensity-modulated radiotherapy (IMRT) and volumetric modulated radiotherapy (VMAT) plans with simultaneous integrated boost (SIB) technique in cervical cancer patients with para-aortic lymph node (PALN) metastases. METHODS SIB-IMRT and SIB-VMAT plans of 10 patients were retrospectively analyzed. The elective volume received 45 Gy(PTV45) in 25 fractions of 1.8 Gy, while the integrated boost volume (lymph nodes) simultaneously received 55 Gy (PTV55). Using the same dose constraints in optimization, IMRT plans consisted of 9 fields, while VMAT plans were performed with 2 full arcs. Volume and dose parameters were determined across the planning target volume, bladder, bowel, femoral heads, kidneys, liver, rectum, sigmoid, and spinal cord. Conformity and homogeneity indices were calculated, the Monitor Unit (MU) was analyzed, and the Wilcoxon-signed rank test was applied for statistical analysis (p≤0.05). RESULTS Both techniques were found to be effective for treatment, but there was a significant difference in favor of SIB-VMAT in terms of target volume reaching the predicted dose and protection of critical organs (OAR) (p=0.028). For PTV55, MU and right-left kidney; V20, V30 - V20, V30, liver; Dort, liver values were significantly different (p=0.005, p=0.005, p=0.005, p=0.02, p=0.005, p=0.007, p=0.03, respectively). In SIB-IMRT, a significant difference was observed for CI value close to 1 (p=0.02). CONCLUSION The SIB-VMAT technique showed lower MU, kidney, and liver values, and SIB-IMRT showed better CI values. Other parameters indicated that the two planning techniques were nearly equivalent. These findings indicate the different efficacies of treatment techniques in radiotherapy planning for cervical cancer patients who were diagnosed with PALN metastases. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to minimize the radiation dose to organs other than the target tissue during adjuvant therapy applied for breast cancer, by using different planning methods. Materials and Methods: 30 women with T1-2 N1-3 M0 breast cancer were included in the study. Planning was performed using four different methods to the supraclavicular area, internal, and external tangential fields. All planning was done in a virtual environment by and the requested data was obtained. All patients were treated by the 1st method. Method 1: Different isocenter, complete supraclavicular area, breast half beam. Method 2: Different isocenter, half supraclavicular area, breast half beam. Method 3: Single isocenter, half supraclavicular area, breast half beam. Method 4: Different isocenter, supraclavicular area full beam, breast full beam. Results: Evaluation of PTV values showed a statistically significant reduction in D-max, 110% and 115% values by method III. Lower doses in other parameters were not statistically significant. Conclusion: Based on these results, the application of single isocenter, 3D radiotherapy in breast cancer provides significant advantages especially in PTV and pulmonary dosages. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of dental implant materials with different physical densities on dose distribution for head and neck cancer radiotherapy planning. Titanium (Ti), Titanium alloy (Ti-6Al-4V), Zirconia (Y-TZP), Zirconium oxide (ZrO2), Alumina (Al2O3) and polyetheretherketone (PEEK) dental implant materials were used for determination of implant material effect on dose distribution. Dental implant effect was investigated by using pencil beam convolution (PBC) algorithm of Eclipse treatment planning systems (TPS) and Monte Carlo (MC) simulation technique. 6 MV photon beam of the Varian 2300 C/D linear accelerator was simulated by EGSnrc-based BEAMnrc MC code system. Reasonable consistency was determined for percentage depth dose (PDD) curves between MC simulation and water phantom measurements at 6.4 MeV initial electron energy. The consistency between modelled linear accelerator PDD curve calculations and water-phantom PDD measurements were compatible within 1 % range. The dose increase in front of the dental implant calculated by MC simulation is in the range of 0.4–20.2%. We found by MC and PBC calculations that the differences in dose increase in front of the dental implant materials is in the range of 0.1–17.2% and is dependent on the physical density of the dental implant. Dose increase for Zirconia was noted to be maximum while PEEK implant dose increase was minimum among the whole dental implant materials studied. This study revealed that the Eclipse TPS PBC algorithm could not accurately estimate the backscatter radiation from dental implant materials. [ABSTRACT FROM AUTHOR]