Radiation and Environmental Biophysics最新文献

The aim of our study is to evaluate the effects of glutamine, partially hydrolyzed guar gum and combined glutamine and partially hydrolyzed guar gum form in rats with experimental radiation enteritis by histopathological, immunohistochemical and biochemical measurements. 64 Wistar albino rats with an average weight of 220-280 g were used in the study. 1st group only took water, 2nd group only took glutamine, 3rd group only took partially hydrolyzed guar gum, 4th group took partially hydrolyzed guar gum with glutamine, 5th group took only radiotherapy, 6th group took radiotherapy with glutamine, 7th group took radiotherapy with partially hydrolyzed guar gum and 8th group took radiotherapy, glutamine and guar gum. Partially hydrolyzed guar gum was given with radiotherapy, and glutamine and guar gum were given together with radiotherapy in the 8th group. All rats were weighed on the first, seventh and tenth days. On the tenth day, the rats were sacrificed and their clinical status, biochemical, histopathological and immunohistochemical parameters in the terminal ileum were evaluated. Differences between groups were compared statistically. All groups were compared in terms of crypt length, villus height, crypt abscess, congestion, intraepithelial lymphoid infiltration, stool consistency, myeloperoxidase, malondialdehyde, caspase-3% and tumor necrosis factor alpha mean, and statistical significance was observed (p < 0.05). Weight% difference in rats was statistically significant between groups (p < 0.05). Interleukin-10 values were not statistically significant between groups (p > 0.05). In paired comparisons, there was a statistically significant difference between the control group and the group with radiation enteritis in terms of biochemical, histopathological, immunohistochemical and clinical parameters (p < 0.05). There was no statistically significant difference between the 5th group and 6th group, 7th group and 8th groups in terms of biochemical, histopathological, immunohistochemical and clinical parameters (p > 0,05). The result suggest that glutamine, partially hydrolyzed guar gum and combination therapy may not have a protective effect on radiation enteritis.

An intracavity balloon filled with ¹³¹Cs liquid was investigated to be used in brachytherapy, particularly for the treatment of glioblastoma multiforme (GBM), with a reference of 40-60 Gy at a depth of 1 cm. The dosimetric characteristics of the liquid ¹³¹Cs, as a low-energy photon source for brachytherapy, were assessed. For this, thermoluminescence dosimetry was used for experimental validation, while Monte Carlo calculations were performed to evaluate dose rate distributions for treatment planning. To prepare the ¹³¹Cs solution, natural BaCO₃ was used as a target irradiated in a thermal neutron flux of 3.5 × 10¹³ n/cm²/s at the Tehran Research Reactor (TRR), and the separation of ¹³¹Cs with a radionuclide purity of 99% was confirmed using a radiochemical method. A well counter was employed to measure the activity of the ¹³¹Cs solution. The dosimetric measurements were conducted using a newly designed phantom in the form of a hollow sphere, as well as a water tank and thermoluminescence dosimeters (TLDs). The results were utilized to validate the accuracy of the dose distribution simulated with the MCNP5 Monte Carlo radiation transport code and a volumetric dose algorithm for predicting dose to water. The ± 8% agreement obtained between TLD measurements and MCNP5 simulations (with an uncertainty of ± 12.3%) confirms the validity of the model. The calculated dose rates in water and brain tissue were 0.0127 Gy/h and 0.0131 Gy/h at a reference depth of 0.5 cm per 37MBq, respectively. To calculate the activity relative to the balloon volume, two equations were deduced for volumes below and above 15 cm³. The results indicate that the validated dose rate can be used to develop a treatment planning method including a liquid ¹³¹Cs source for brachytherapy applications.

This study aimed to determine the most appropriate treatment planning solution for prostate cancer radiotherapy by analyzing the effect of planning parameters on dosimetric outcome. Four volumetric modulated arc therapy (VMAT) / intensity modulated radiation therapy (IMRT) plans were created for each of the 20 patients included in the study, using minimum segment width (MSW) of 0.5, 1.0, 1.5, and 2.0 cm. All prostate plans underwent "Fluence Smoothing" on "High", while plans using MSW = 1.0 were reoptimized with both "Low" and "Medium" settings. All plans met the planning objectives. MSW = 0.5 resulted in better tumour coverage (by over 0.3 Gy), enhanced conformity and better sparing for the majority of organs at risk (OARs). However, this small MSW was associated with a notable increase in monitor units (MUs) (by over 300), control points (CPs) (by over 83) and delivery time (DT) (by over 0.88 min). The most significant impact of reduced fluence smoothing was observed in parameters such as MUs (reduced by over 53) and DT (reduced by over 0.15 min), which improved gamma passing rate (GPR). In the context of dosimetric outcomes, variations in fluence smoothing had minimal effect on the dose distribution to the planning target volume and most OARs. It is concluded that clinically acceptable dose distributions were achieved across all segment widths and fluence smoothing levels. However, using a 1.0 cm MSW with medium-to-high fluence smoothing provided a favourable balance between plan quality, delivery accuracy and efficiency in prostate cancer, without compromising dosimetric outcomes.