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: In this study, a comparison between various types of radiotherapy treatment for parotid gland cancer was performed to achieve the optimal treatment technique.Methods: Treatment planning and countering performed with TiGRT software for 15 patents with parotid gland cancer. Six techniques were performed and compared. Finally, by comparing the dose volume histograms (DVH), average dose received by each organ was determined and the best method was introduced. Techniques were as: 1. an ipsilateral wedge pair technique using 6 MV photons; 2. a 3-field anteroposterior (AP) (wedged) posteroanterior (PA) (wedged) and lateral portal technique using 6 MV photons; 3. a mixed beam technique using 6 MV photons and 12 MeV electrons (1: 4 weighting); 4. a mixed beam technique using 6 MV photons and 15 MeV electrons (1: 4 weighting); 5: four 6 MV photon beams with different gantry angles; and 6. similar to fifth technique with an additional small ring around the tumor tissue. Findings: Intensity-modulated arc therapy (IMRT) techniques five and six delivered maximum dose to the target and minimum dose to organ at risks (OAR). Among 3-D conformal radiotherapy techniques (CRT), technique number two delivered more amount of dose to the target than techniques number three and four. The dose delivered to the contrary parotid gland was negligible for intensity-modulated arc therapy techniques.Conclusion: Intensity-modulated arc therapy techniques are most appropriate methods for treating cancer of the parotid gland and the sixth technique delivered better dose distribution in the tumor and healthy tissues. Second D conformal radiotherapy technique delivered higher average dose to the target.

Background: Intensity-Modulated Radiation Therapy (IMRT) is one of the best methods in the treatment of optic nerve sheath meningioma (ONSM) with tumor growth control and visual stabilization. In this study, various IMRT techniques were evaluated from the point of view of dose fall-off beyond the target boundaries to achieve the optimal technique. Methods: The optimization of 3 IMRT techniques was performed using 3, 5, and 7 fields with 6 MV photons in 15 patients with ONSM using Prowess Panther treatment planning system. To evaluate treatment plans, in addition to data extracted from dose-volume histogram (DVH) and evaluation of target coverage indices, differential and cumulative dose gradient indices (DGIs) were calculated and compared between the three techniques. Findings: The maximum and the mean dose received by the tumor increased with increasing number of IMRT fields. The uniformity (UI) and homogeneity (HI) indices were significantly different between the 3-field and 7-field techniques; and the conformity index (CI) was close to ideal value (0. 99) in 7-field technique. Difference of differential dose gradient index (dDGI) was negligible between the three techniques, and only at the 45% isodose level, there was a significant difference between the 5-and 7-field techniques. Cumulative dose gradient index (cDGI) showed smaller values in 7-field technique than the other two techniques. Conclusion: The three IMRT techniques have no considerable statistical difference in dose fall-off rate beyond tumor boundaries; and their choice in the treatment of ONSM depends on the physician's discretion based on the whole patient's conditions.

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: This study aimed to determine hippocampal absorbed dose in radiotherapy of high-grade brain glioma using dose painting method and to compare it with intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT).Methods: In Milad hospital radiotherapy section in Isfahan, Iran, images from 24 patients with high-grade brain glioma were acquired. All radiotherapy volumes for patients were defined and then, at risk organ was contoured. There were 4 planning target volumes (PTVs) defined for each patient. PTV4 just has been defined for dose painting method and the given dose was increased up to 72 Gy in this method. Finally for each patient, by using treatment planning system characteristics, 3 methods were simulated and the optimal technique was represented. Findings: The average hippocampus-received dose was 4.772, 4.174, and 5.668 Gy in 3D-CRT, IMRT, and dose painting methods, respectively. Increasing the dose in dose painting method by 1.2% than in IMRT method resulted in 1.357% increasing in hippocampal-absorbed dose; considering the hippocampal tolerance dose, it would not cause serious injury and in return tumors, would be controlled more effectively.Conclusion: In this study, the importance of multi-parametric magnetic resonance imaging (MRI) in dose painting method was achieved. As by using these images for determining the different parts of tumor, tumor-received dose significantly increased; while the organs around the tumor received no serious damage.

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.