ABSTRACT
Purpose@#The purpose of this study was to investigate the incidence of short-term atherosclerosis in the common carotid arteries following radiotherapy. @*Methods@#The mean radiation dose to the arteries was 49.30±15.83 Gy. A computational ultrasound method was introduced to investigate the elastic modulus. Ultrasonography was performed 2-3 cm inferior to the bifurcation region before and after radiotherapy, and sequential images were extracted from a video of each artery. Instantaneous movement of the arterial wall in the radial and longitudinal directions was extracted by implementing the maximum gradient and block matching algorithms, respectively. @*Results@#There was a significant change in systolic blood pressure after radiotherapy (P=0.008). Irradiated arteries had significantly smaller systolic and end-diastolic diameters than non-irradiated arteries (P<0.001). The shear modulus was significantly different between irradiated and non-irradiated arteries (3.10±2.03 kPa vs. 1.38±0.98 kPa, P<0.001). The shear and Young moduli of radiation-induced arteries were 2.25±1.50 and 1.57±0.59 times higher than those of the pre-irradiation arteries. @*Conclusion@#The arterial shear modulus can be considered as a new biomarker of radiationinduced atherosclerosis in the common carotid artery.
ABSTRACT
This study was designed to evaluate dosimetric parameters such as rectal dose, bladder dose, integral dose [ID], homogeneity index [HI] and conformity index [CI] in various treatment plans for prostate cancer. Pelvic computed tomography [CT] scans of 27 patients were acquired and transferred to the RTDosePLAN treatment planning system. For each patient, 8 conventional plans [3, 4, 5 and 6 fields] were planned for the cobalt-60 photon energy. Subsequently, the same plans were performed for 6 MY and 18 MY photon energies. By increasing the energy of the beam relative to the cobalt-60 energy, the D[mean] values for rectum and bladder were reduced from 3% to 4% and 4% to 6%, respectively, the dose received by the whole of the bladder volume decreased by 26% for 6 MV and by 58% for 18 MV. Increasing the photon beam energy decreased CI to 7% and 10% ID was decreased by l0% and 20% and D[max] was decreased by 3% and 4% respectively. A six-field treatment plan in comparison to the other plans offers the minimum dose to critical organs and sufficient dose to the prostate. Increasing the photon energy improves the treatment parameters of the bladder and the PTV