Background: Breast cancer is the most common malignant neoplasm in women, accounting for 25% of all cancers. Radiotherapy is one of the safest methods compared with other treatments.Methods: In this study, 8 patients with left breast cancer underwent the radiation therapy. After simulating the tomographic data of breast cancer patients, treatment planning was performed in the treatment planning system, and then the clinical target volume and the planned target volume were determined.Results: The mean CI (1.162 ± 0.011) in Intensity Modulated Radiation Therapy (IMRT) was significantly lower than CI (1.173 ± 0.28) in Volumetric Arc Radiation Therapy (VMAT) (P ≤ 0.02), indicates that IMRT technique had lower CI which means better dose conformity within the PTV. Also, the mean HI (0.696 ± 0.333) in VMAT was significant compared to IMRT, the mean HI (0.558 ± 0.288) (P ≤ 0.04), the results on better PTV dose distribution by using VMAT technique. Planning target volume (PTV) was consistent with indicators and PTV coverage value (97.563 ± 1.471) in IMRT and (96.677 ± 1.018) in VMAT, means that the PTV coverage was better by using IMRT technique rather than VMAT. The mean dose to left breast was (42.118 ± 0464) prescribed dose. Ref. vol. CC, D2%, and D98% were received (736.898 ± 235.140), (4618.931 ± 107.658), and (3765.475 ± 71.195), respectively.Conclusion: IMRT method is one of the new cancer treatment techniques that in comparison with other methods by accurately targeting cancer cells and tumors, it has the least impact on healthy tissues and reduces the side effects as much as possible.

Background: Grid radiation therapy, using the megavoltage X-ray beam, has been proven to be an effective method for management of large and bulky malignant tumors. This treatment modality is also known as Specially Fractionated Radiation Therapy (SFRT). In this treatment technique a grid block converted the open radiation field into a series of pencil beams. Dosimetric characteristics of an external beam grid radiation field have been investigated using experimental and Monte Carlo simulation technique.Materials and Methods: Dose distributions (%DD as well as the beam profiles) of a grid radiation field have been determined using experimental and Monte Carlo simulation technique, for 6- and 18 MV X-ray beams from a Varian Clinics 2100C/D. The measurements were performed using LiF TLD and film in Solid Water phantom Material. Moreover, the MCNP Monte Carlo code was utilized to calculate the dose distribution in the grid radiation field in the same phantom material. The results of the experimental data were compared to the theoretical values, to validate this technique. Upon the agreement between the two techniques, dose distributions can be calculated for the grid field with different patterns and sizes of holes, in order to find an optimal design of the grid block.Results: The results of dose profiles for 6 MV X-ray beams obtained with the Monte Carlo simulation technique was in good agreement with the measured data. In addition, the 3D dose distribution of the grid field generated by the Monte Carlo simulation gave more detailed information about the dose pattern of the grid. Conclusion: The grid block can be used as a boost for treatment of bulky tumors. The Monte Carlo simulation technique can be utilized to optimize the pattern, size and spacing between the holes, for optimal clinical results

Background: The commissioning accuracy of Volumetric Modulated Arc Therapy (VMAT) need to be evaluated. Objective: To test and evaluate commissioning accuracy of VMAT based on the TG 119 protocols at local institution. Material and Methods: The phantom, structure sets, VMAT and IMRT beam parameter setup, dose prescriptions and planning objectives were following TG 119 guidelines to create local treatment plans of VMAT and IMRT. The local planning results were compared with the results of TG 119. Point measurement at high and low dose regions were measured using three ionization chambers with different active volumes (CC01, CC13, FC65G). The composite dose was measured by a 2D detector array and analyzed for the percentage of points passing the gamma criteria of 3 % dose difference (DD) and 3 mm distance-to-agreement (DTA) and 2 % DD and 2 mm DTA. Results: The local treatment plans of VMAT and IMRT capable to meet the dose goals criteria set by TG 119 except for C-shape hard. Three ionization chambers with various active volumes for point measurement showed an increase in the confidence limit (CL), the larger the active volume was found proportional to increase the value of CL. The results obtained from ion chambers CC01 and CC13 could met the dose criteria set by TG 119, but results obtained from ion chamber FC65G fail the criteria. All gamma evaluation results show more than 95% data points pass the criteria of 3% DD and 3 mm DTA and the gamma index CL results fall within the TG 119 criteria, which is below 12. 4. Conclusion: TG 119 methodology and recommendations have successfully been used to evaluate commissioning accuracy of VMAT. The CL value of the study could be used as a reference and recommendation to evaluate the accuracy and integrity of treatment planning and treatment delivery systems of VMAT and IMRT.

Introduction: With the introduction of Intensity Modulated Radiotherapy (IMRT) approach, better dosimetry results and patient outcomes has been attained for various anatomical sites. In present study, a comparative dosimetric evaluation of Volumetric-Modulated Arc Therapy (VMAT) versus two techniques of IMRT i. e. Dynamic IMRT (d-IMRT) and step & shoot IMRT (ss-IMRT) was done for thoracic esophageal cancer. Material and Methods: VMAT, ss-IMRT, and d-IMRT plans were generated on the Computed Tomography Simulator data sets of 13 Patients with thoracic esophageal carcinoma who had been treated earlier. The prescription dose for each patient was 50. 4 Gy in 28 fractions. All the plans were optimized to achieve greater or equal to 95% of the prescribed dose to the Planning Target Volume (PTV). Dose to PTV and organ at risk (OAR) were compared with the help of Dose Volume Histogram (DVH). Results: VMAT and d-IMRT plans were nearly equivalent for PTV coverage, homogeneity index (HI), and uniformity index (UI) (p> 0. 05). However, VMAT and d-IMRT plans had superior PTV coverage, HI, and UI, (p < 0. 01) than ss-IMRT. For PTV, the Dmean, D98, and D95 values in ss-IMRT were significantly less than VMAT and d-IMRT (p< 0. 05). Conclusion: All three techniques are able to provide a homogeneous and conformal dose distribution. VMAT offers better homogeneous dose distribution and may be preferred for treating thoracic esophageal carcinoma. Thus, the multi-arc VMAT technique may be a better option with equivalent or superior dose distribution, uniformity, and homogeneity.