Non-surgical Treatments of Esophageal Cancer

    Esophageal cancer is one of the most common malignancies with a growing occurrence. It presently ranks ninth among the most frequent cancers in the world and the sixth leading cause of death from cancer. For a variety of reasons, the mainstream of patients with esophageal cancer is actually not suitable for Esophagectomy. More than 50% have locally advanced unresectable or metastatic tumors at diagnosis. Other reasons which exclude Esophagectomy include old age, comorbidity or refusal by the patient. For more advanced stages of esophageal cancers, the basis of non-surgical treatment is chemotherapy (CT) or radiotherapy (RT), either alone or in combination as chemoradiotherapy (CRT). The purpose of this study is to summaries and judgmentally analyzes current non-surgical treatments. Although the best treatment for locally advanced esophageal cancer is still being debated, the use of neoadjuvant chemoradiotherapy has gained acceptance

Determination of primary electron beam parameters in a Siemens Primus Linac using Monte Carlo simulation

The Monte Carlo method can be used to describe any technique that approximates solutions to quantitative problems through statistical sampling. This method is considered to be the most accurate method for dose calculation in radiotherapy. For complete modeling of a linear accelerator, it is required that the manufactured information covers all data, but some data such as primary electron energy must be indicated. The purpose of this study was to determine the best primary electron energy for 15 MV photon beam with varying the energy and FWHM. A Monte Carlo model for photon-beam output of a Siemens primus linear accelerator was validated by plotting the energy spectrum of photon beam and calculating the percentage depth dose (PDD) and beam profiles for 10×10 cm2 field. Square 10×10 cm2 field was validated by measurements in water by a farmer chamber. Linac head simulation was performed with BEAMnrc and dose calculation and 3D dose file were produced by DOSXYZnrc. The results were analyzed using MATLAB. It was found a good agreement between calculated PDD and beam profile for 15 MV photon beam using Monte Carlo simulation with primary electron energy of 11 MV and FWHM of 0.4 with maximum dose difference of 1.2% in PDD curves. In conclusion, using primary electron energy of 11 MV and FWHM of 0.4 has very good accuracy in calculating of dose distribution for 15 MV photon beam and it can be considered as a promising method for patient dose calculations

Analysis of Hip Joint Dose in Prostate Cancer Radiation Therapy: A Dosimetric Comparison of Treatment Plans

Background and purpose: Radiation therapy as a part of cancer treatment is used in almost 50-60% of involved cases. In prostate cancer radiation therapy, a large volume of pelvis is irradiated, so, it is necessary to preserve sensitive organs around the treatment area, especially rectum and bladder. In this study, some dosimetric parameters such as minimum dose (Dmin), maximum dose (Dmax), mean dose (Dmean) to target (PTV) and organs at risk (OAR), Integral dose, Homogeneity Index and Conformity Index were compared between two techniques. Materials and methods: In this analytical study, computed tomography scans of 50 patients (mean age: 52 years) attending Sari Imam Khomeini Hospital were acquired and transferred to the 3D treatment planning system (TPS). For each patient, a conventional plan (Box Fields) and modified oblique four-field (MOFF) plan were prepared using TPS for 15 MV photon energy. A total dose of 7200 cGy was prescribed for each patient. Data analysis was carried out in SPSS applying paired-t-test. Results: In current study, 15-MV energies for radiation of pelvis and bladder using box radiation fields (routine plan) lead to maximum uniformity and homogeneity of dose in irradiated tumor tissue. The results also showed that 15-MV energies for radiation of pelvis and bladder and the new plan could decrease the average integrated dose in femur heads. Conclusion: We observed a significant effect of the geometrics of radiation fields on distribution of dose in tumor tissue and also the amount of dose received by organs at risk in radiotherapy of patients with prostate cancer

Evaluation of Lung Dose in Esophageal Cancer Radiotherapy Using Monte Carlo Simulation

Background and purpose: Radiation therapy make an important contribution in the control and treatment of cancers. Lungs are the main organs at risk in esophageal cancer radiotherapy. Difference between the dose distribution due to the treatment planning system (TPS) and the patient's body dose is dependent on the calculation of the treatment planning system algorithm, which is more pronounced in heterogeneities such as the lung. In this study, the dose distribution of treatment planning system was compared with Monte Carlo calculations in both homogeneous and heterogeneous tissues. Materials and methods: Three dimensional planning composed of four fields were done on the CT images using the CorPLAN TPS of a SIEMENS PRIMUS linac. EGSnrc Monte Carlo simulation code was used for the same conditions. The dose distributions obtained from Monte Carlo simulation and the TPS were compared using PDD curve and Dose Difference Percentage index obtained from the two modes. Results: According to the findings, the error rate from the TPS was less than 3% in the homogeneous tissue, whereas the error in the heterogeneous tissue was higher than the standard value (more than 5%). Conclusion: The accuracy of CorPLAN TPS at homogeneous tissue is more than that in the heterogeneous tissue and this should be considered in the clinic. This study suggests that the Monte Carlo code can be used to simulate and estimate the dose distribution in radiotherapy, and in cases where the practical measurement of some dosimetric parameters is impossible or difficult, this code can be used for prediction and optimization of treatment plans

Development and Characterization of Hemicellulose-Based Films for Antibacterial Wound-Dressing Application

Hemicelluloses are biopolymers with versatile properties for biomedical applications. Herein, hemicellulose (arabinoxylan)-based antibacterial film dressings were prepared and characterized. Arabinoxylan was isolated from psyllium husk. Blank and gentamicin-loaded films were prepared by the solvent cast method using glycerol as the plasticizer. The appropriate composition of the films was obtained by varying the amounts of arabinoxylan, glycerol, and gentamicin. The films were found to be transparent, smooth, bubble-free, flexible, and easily peelable with 2% to 3% arabinoxylan. They had uniform thickness and swelled up to 60% of their initial size. The mechanical properties and water vapor transmission rate through the films were found to be suitable for wound-dressing application. Fourier transform infrared spectroscopy (FTIR) analysis confirmed drug–film compatibility. In an in vitro release study, more than 85% of the gentamicin was released from the films in 12 h. The antibacterial activities of the gentamicin-loaded films were found to be close to the standard gentamicin solution. The films were found to be cytocompatible in cell viability assay. These results suggested that hemicellulose-based films are promising materials for the dressing of infected wounds