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: 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.

The present study aimed at identifying monitor unit (MU), treatment time variations, volume coverage dissimilarity, and second tumor incidence among Volumetric modulated Arc therapy (VMAT), Intensity modulated radiation therapy (IMRT), and 3D-Conformal radiation therapy (3D-CRT), and treatment plans for prostate cancer based on literature review. A literature search was conducted on Pubmed/MEDLINE, BioMed Central (BMC)-part of Springer Nature, Google Scholar, and Insight Medical Publishing (iMED-Pub LTD) using the following keywords for filtering: 3D-CRT, IMRT, VMAT, Prostate Cancer, Conformity, and Homogeneity Index. IMRT was consisted of several treatment fields with different directions, hundreds of beamlets with modulated Intensity, and an advantage over 3D-CRT, whereas VMAT had the advantage over IMRT due to rotating-beam utilization. VMAT usually required a longer dose optimization time and a rapid treatment, allowing patient comfort, reduced intrafraction motion, and increased throughput compared to IMRT and 3D-CRT. VMAT has slightly better conformity and homogeneity with lower doses to normal tissue and MUs and treatment times compared to IMRT and 3D-CRT. Lower MUs reduce the risk of secondary malignancies. If target coverage and normal tissue sparing are comparable among different techniques, the risk of secondary malignancy should then be an important factor to choose the treatment modality.

Intensity modulated radiation therapy is one of the most commonly used procedures of delivering radiation to cancerous tissues، with the aim of reaching the prescripted dose in the target volume while minimizing damage to nearby healthy organs. Two decisions are of fundamental importance: to select the beam angles and calculate the beam intensities. Beam Angle selection (Beam Angle Optimization) is an important problem and most of the time، beam angles are manually selecteld based on human experience and intuition. In this study، we propose a hybrid approach for automated beam angle selection and computing beam intensities، that aims to find good feasible solutions quickly and then used the solution as a starting point for Local Neighborhood Search to find local optimal solution. Numerical results demonstrated that hybrid approaches in comparison with their corresponding stand-alone methods، quickly and consistently find good local optimal solutions.

Although many methods exist for Intensity modulated radiotherapy (IMRT) fluence map optimization for crisp data, based on clinical practice, some of the involved parameters are fuzzy. In this paper, the best fluence maps for an IMRT procedure were identifed as a solution of an optimization problem with a quadratic objective function, where the prescribed target dose vector was fuzzy. First, a defuzzying procedure was introduced to change the fuzzy model of the problem into an equivalent non-fuzzy one. Since the solution set was nonconvex, the optimal solution was then obtained by performing a projection operation in applying the gradient method. Numerical simulations for two typical clinical cases (for prostate and head-and-neck cancers, each for two patients) are given.

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: To investigate a method for standardizing Intensity modulated radiation therapy (IMRT) optimization for nasopharyngeal carcinoma (NPC), in order to reduce the influence of subjective factors. Materials and Methods: This study is based on example IMRT plans for NPC, which were randomly divided into data acquisition and data verification groups. Organs at risk (OARs) were analyzed for various sub-organs. The data acquisition group was used for statistical evaluations of the mean value of the normalized mean doses of sub-organs. The data validation group was used to validate the findings. Results: Significant negative correlations were observed between the normalized mean doses of sub-organs for each OAR and the shortest distance between sub-organs and the target region surface. For each OAR, there was no statistically significant difference in the normalized mean doses of sub-organs between the data acquisition and verification groups (p > 0. 05). Conclusion: The influence of subjective factors can be reduced by using the normalized mean doses of suborgans for each OAR as the evaluation parameter for standardizing. This method is relatively simple; a majority of radiotherapy centers can apply the model for standardizing IMRT planning optimization based on the existing planning system.