The aim of this study was to assess the actual dose delivered to the rectum and compare it with the treatment planning system (TPS) reports. In this study, the dose delivered to the rectum was measured by semiconductor diode detectors (PTW, Germany). The factors that influence diode response were investigated as well. Calibration factors of diodes were measured weekly to investigate the effect of time interval on the accuracy of calibration. Then 40 applications of patients with cervix carcinoma were evaluated. Rectum dose was measured by means of rectal dosemeter and compared with the TPS-calculated dose. In this research, the differences between the measured and the calculated dose were investigated. The mean difference between the TPS-calculated dose and the measured dose was 6.5% (range: -22 to +39) for rectum. The TPS-calculated maximum dose was typically higher than the measured maximum dose. The study showed that the main reason for the difference was due to the movements of the patient and applicator shift in the elapsed time between the imaging and treatment stage. It is recommended that in vivo dosimetry should be performed in addition to treatment planning computation. In vivo dosimetry is a reliable solution to compare the planned and actual dose delivered to organs at risk.

Background We investigated the effect of dual‐frequency sonication on the viability of B16F10 melanoma cells in the presence of methylene blue (MB) encapsulated in nanoliposomes. Methods Treatment protocols were studied: sonication groups (40 kHz, 1 MHz and dual‐frequency), the same sonication groups with nanoliposomes containing MB, MB free and nanoliposomes containing MB groups, and so sham and control groups. The nanoliposomes were prepared by the lipid film hydration method. The cell viability of the different treatment groups was evaluated by the MTT assay. Results The dual‐frequency protocols caused higher viability losses compared to the kHz and MHz sonications (P < .05). In presence of the nanoliposomes containing MB, dual frequency led to 6% and 3% viability for 600 and 1200 seconds, respectively, while the corresponding values were 10% and 4% for the 40 kHz protocols and 22% and 9% for the 1 MHz, as compared to the control group (100%). The result of KI dosimetry showed that the cavitation activity of the dual‐frequency protocol was about 1.23, as compared to sonication at 40 kHz and 1 MHz. Conclusion Enhancement of inertial cavitation induction by dual‐frequency sonication may be the primary effective mechanism, which causes increased sonochemical processes and drug release from nanocarriers.

The aim of this work was to present a theoretical analysis of how phantom dimensions and tissue heterogeneities in interstitial brachytherapy affect on dose distributions. This work was carried out using Gafchromic film measurement and Monte Carlo simulation for 192 Ir source. Results show that treatment planning systems (TPS) which consider the patient geometry as homogeneous medium, lead to a dose underestimation up to 8.2% for lung and an overestimation up to 9% for bone. These values depend on the thickness and distance from the source. Thus, TPSs currently in use for clinical brachytherapy cannot consider the effect of tissue heterogeneity on dose distribution.