Background: We aimed to investigate the accordance of Critical Organ Scoring Index (COSI), Conformity Index (CI) and Normal Tissue Complication Probability (NTCP) parameters with Dose Volume Histograms (DVH) used for evaluation of 3 different pelvic radiotherapy plans. Materials and Methods: Ten gynecologic carcinoma patients who underwent adjuvant radiotherapy were enrolled in this study. Treatment plans were created with conformal treatment planning (3DCRT) and intensity modulated radiation therapy (IMRT) to a total dose of 50. 4 Gy in 28 fractions. Initially, volume related dose evaluation was done via DVH. Subsequently, HI, CI, COSI and NTCP for selected normal tissues were calculated for each plan and compared with DVH parameters. Finally, a graphical demonstration was evaluated to see if the results were in accordance with DVH. Results: CI results were statistically significant in favor of IMRT (p<0. 001). Rectum V40Gy decreased with 9IMRT compared to 3DCRT and 7IMRT (p=0. 013 and p=0. 013). V40Gy for bladder was also lower with 9IMRT compared with 3DCRT and 7IMRT (p=0. 005 and p=0. 012). COSI calculations revealed better small intestine protection in IMRT plans similar with DVH (p=0. 005 and p=0. 022). Femoral heads were better protected with IMRT plans were better compared to 3DCRT in NTCP calculations (p=0. 002). Normal tissue protection was worst with 3DCRT via both DVH and COSI evaluations (p=0. 001 and p<0. 001 respectively). Conclusion: Using the indexes in this study to decide the most appropriate plan among multiple treatment plans in gynecologic cancer patients will be timesaving and easier in comparison with evaluating the DVH of every alternative plan.

Background: Radiation-induced lung toxicity is an important dose-limiting toxicity in lung cancer radiotherapy, for which there are no generally accepted predictive factors. This study seeks to identify risk factors associated with the development of severe radiation-induced lung toxicity using clinical and dosimetric parameters.Methods: We reviewed the medical records of 54 patients with histologically proven stage III non-small cell lung cancer treated with three dimensional-conformal radiotherapy at Alexandria Main University Hospital between January 2008 and December 2011. The original treatment plans for those patients were restored and imported to a treatment planning system. Lung dose–volume histograms and various dosimetric parameters were calculated. Univariate and multivariate logistic regression analyses were performed.Results: The following grades of radiation-induced lung toxicity were observed in patients - grade 0: 17 (31.5%), grade 1: 5 (9.3%), grade 2: 13 (24.1%), grade 3: 15 (27.8%), and grade 5: 4 (7.4%). A total of 19 (35.2%) patients developed grade ≥3 and were considered to have an event. Univariate analysis showed that age, presence of chronic obstructive pulmonary disease and location of the primary tumor had significant associations with severe radiation-induced lung toxicity. Other dosimetric variables such as tumor side, histology, forced expiratory volume in 1 s, smoking, and gender showed no significant correlations with severe radiation-induced lung toxicity. Multivariate analysis showed that the presence of chronic obstructive pulmonary disease (P=0.001) and location of the primary tumor (P=0.010) were the only predictive factors for severe radiation-induced lung toxicity.Conclusion: This study demonstrates that patients with chronic obstructive pulmonary disease and lower lung lobe tumors have a high risk of severe radiationinduced lung toxicity when treated with combined chemoradiotherapy. These easily obtained clinical factors should be considered when calculating the risk for radiationinduced lung toxicity.

Background: Radiation induced esophageal toxicity is a primary cause of treatment interruptions in the radiotherapy of lung cancer, for which there are no clear predictive factors. This study attempts to identify risk factors associated with the development of severe radiation induced esophageal toxicity using clinical and dosimetric parameters.Methods: We reviewed the medical records of 54 patients with histologically proven stage III non-small cell lung cancer treated with 3D-conformal radiotherapy at Alexandria Main University Hospital between January 2008 and December 2011. The original treatment plans for those patients were restored and imported to the treatment planning system. The external surface of esophagus was contoured for each patient. We calculated the esophagus dose–volume histograms and various dosimetric parameters. Univariate and multivariate logistic regression analyses were performed.Results: Of the 54 patients, 6 (11.1%) had grade 3 radiation induced esophageal toxicity and 2 (3.7%) had grade 4. There was no grade 5 toxicity. The most statistically significant parameters for predicting RIET grade 3 or worse included esophageal volume that received ³50 Gy (V50), esophageal volume that received ³55 Gy (V55), and the use of concurrent chemotherapy according to univariate and multivariate logistic regression analyses.Conclusion: This study demonstrates that the best predictive factors for severe early radiation induced esophageal toxicity are concurrent chemotherapy, and esophageal volumes ³50 Gy and ³55 Gy in non-small cell lung cancer treated with 3D-conformal radiotherapy.

Background: The DVH is the most used radiotherapy formulation. DVH plays a fundamental role in determining dose constraints and side effects. Volume also plays the main role in calculating DVH. In prostate treatment, there is no comprehensive consensus on determining the association between bladder volume (BV) and side effects. Our aim is to investigate the reproducibility of bladder DVH (DVHB). D50%BV (dose received by 50% of BV) is used to analysis DVHB. Materials and Methods: We contoured the bladder of 467 daily MVCT images of fifteen prostate cancer patients who underwent tomotherapy. Using R software 4.2.3, the correlation between the bladder center of mass (XCM, YCM, ZCM), BV with D50%BV were modeled by the mixed model. Two prediction models were presented for D50%BV, the first model was based on BV and (XCM, YCM, ZCM), the second model was based on BV. Results: Statistical analyses revealed that independent factors YCM, ZCM, and BV have a significant influence on the response variable D50%BV. According to mixed model, YCM has a positive correlation with D50%BV, while ZCM or BV has a negative correlation. XCM does not significantly affect D50%BV. Akaike Information Criterion (AIC) index indicated that first model has a higher goodness of fit than second one. Conclusion: Our findings demonstrate that bladder location also affects D50%BV, in addition to BV. It can be concluded that DVHB is not always repeatable as a scientific claim.

Aims: It was aimed to investigate postoperative conformal radiotherapy planning that provides the best target volume and the least dose for critical organs in cancers of stomach.Methods: This study was conducted on the CT simulation images of thirty patients diagnosed with gastric cancer. Target volumes and the organs at risk were contoured. AP-PA reciprocal parallel field conventional plan and three- and four-field 3D conformal plans were created using linear accelerator. Target volumes and doses consumed by organs at risk were compared by dose-volume histograms.Results: While a sufficient dose could be applied to target volumes in all plans with conformal planning, average figures showed that 95% of porta hepatis area failed to take the prescribed dose (D95) in some plans by using AP-PA reciprocal parallel zone conventional plans. The most convenient protection for spinal cord, heart and kidneys was obtained by conformal four-field technique and the liver doses were increased in conformal four-field plans but did not exceed the tolerance dose. And also, in the conventional AP-PA reciprocal parallel field plans, tolerance dose of spinal cord (4500 cGy) was exceeded.Conclusion: In this study, conformal four-field technique was superior considering target volume dose distributions, and especially spinal cord doses in all localizations and heart doses in cardia tumors. Kidney doses were also reduced in conformal four-field planning, but failed to reach statistical significance. There was a not exceeding tolerance limits dose increase in liver.

Background and objective: Three-dimensional conformal radiotherapy (3DCRT) is an advanced radiation treatment technique that shapes the radiation beams to match the shape of the tumor and it is used to treat brain tumors while avoiding radiation to the healthy tissue surrounding brain tumor. The purpose of this study is to evaluate the dosimetric data among the patients with a brain tumor by using three-dimensional conformal radiotherapy (3D-CRT). Methods: In eight patients with brain tumors being treated by 3DCRT, the target, lenses of eyes, optic nerves, brain stem, and open chiasm were contoured. Two opposed lateral fields were used. The prescribed photon beam dose was depending on the type of tumor, in general for all cases is divided into 20 fractions using 6 MV photons. Results: The comparison of 3D-CRT outcomes for all patients showed that the most common location of a tumor in the brain was in GBM in temporal and frontal parts of the brain and consist about 25% to total types of tumor in the brain for patients in this study, more than 62. 5% of patients were treated with doses more than 4400 cGy the homogeneity index was better for patient No. 1 than other patients (0. 0694). The mean dose for the Right lens was higher for patient No. 8 than for other patients was (1530 cGy). While in the left lens the mean dose was higher in patient No. 3 than in other patients was (1501 cGy), and the mean dose for both lenses in all plans for all patients was less than ≤, 10 Gy (the standard tolerance value). The highest mean dose received by the left optic nerve in patients number 2 was (3339 cGy), and the more mean dose received by the right optic nerve in patients number 2 was (3645 cGy), but in both two sides of the optic nerve the mean doses them less than ≤,50 Gy the standard tolerance value. The mean dose received by Brain stem for all patients was less than ≤,50 Gy tolerance dose. The mean dose received by Open Chiasm for all patients was less than ≤,54 Gy tolerance dose Conclusion: This study showed that 3DCRT spared the volume of the healthy tissue surrounding the brain tumor to be irradiated to achieve the most accurate treatment delivery to best planning target volume. The application of 3D-CRT was successful in justification of radiation dose to lower than tolerance dose in all evaluated brain tissues.

Introduction Intensity-Modulated Radiotherapy (IMRT) is becoming an increasingly routine treatment method. IMRT can be delivered by use of conventional Multileaf Collimators (MLCs) and/or physical compensators. One of the most important factors in selecting an appropriate IMRT technique is integral dose. Integral dose is equal to the mean energy deposited in the total irradiated volume of the patient. The aim of the present study was to calculate and compare the integral dose in normal and target organs in two different procedures of IMRT: Step-and-Shoot (SAS) and compensator-based IMRT. Materials and Methods In this comparative study, five patients with prostate cancer were selected. Module Integrated Radiotherapy System was applied, using three energy ranges. In both treatment planning methods, the integral dose dramatically decreased by increasing energy. Results Comparison of two treatment methods showed that on average, the integral dose of body in SAS radiation therapy was about 1. 62% lower than that reported in compensator-based IMRT. In planning target volume, rectum, bladder, and left and right femoral heads, the integral doses for SAS method were 1. 01%, 1. 02%, 1. 11%, 1. 47%, and 1. 40% lower than compensator-based IMRT, respectively. Conclusion Considering the treatment conditions, the definition of dose volume constraints for healthy tissues, and the equal volume of organs in both treatment methods, SAS radiation therapy by providing a lower integral dose seems to be more advantageous and efficient for prostate cancer treatment, compared to compensator-based IMRT.

Introduction: The ultimate goal of radiation treatment planning is to yield a high tumor control probability (TCP) with a low normal tissue complication probability (NTCP). Historically dose volume histogram (DVH) with only volumetric dose distribution was utilized as a popular tool for plan evaluation hence present study aimed to compare the radiobiological effectiveness of the cobalt-60 (Co-60) gamma photon and 6MV X-rays of linear accelerators (Linac) in the radiotherapy of head and neck tumors.Materials and Methods: TCP and NTCP were calculated using DVH through the BIOPLAN software developed by Sanchez-Nieto and Nahum. The treatment planning was performed for all the patients using both treatment modalities (i.e., Co-60 and 6 MV Linac). The TCP was also manually calculated using a mathematical formula proposed by Brenner’s et al.Results: The average TCP calculated by the BIOPLAN for Co-60 and 6 MV X-rays were 44.6% and 60.8%, respectively. Furthermore, the average NTCPs obtained for the organ at risk, namely optic nerve, for Co-60 and 6 MV X-ray were 0.24 % and 0.03 %, respectively. Regarding the spinal cord, the average NTCPs for Co-60 gamma photon and 6 MV X-ray of Linac were 0.05 % and 0.002%, respectively.Conclusion: As the findings of the present study indicated, Co-60 unit could provide comparable TCP along with minimal NTCP, compared to the high-cost technologies of Linac. The design of treatment plans based on the radiobiological parameters facilitated the judicious choice of physical parameters for the achievement of high TCP and low NTCP.

Background: To determine which radiotherapy parameters are associated with the tumor response of locally advanced non-small cell lung cancer (NSCLC) patients undergoing concurrent chemoradiotherapy.Materials and Methods: Thirty one patients with IIIA/IIIB NSCLC underwent chemoradiotherapy with a median dose of 63 Gy. On our actual treatments, we made radiotherapy planning to cover the planning target volume (PTV) with 95% of the prescribed dose, and checked the second CT simulation when a cumulative dose was about 36 Gy. For this study, each PTV of primary tumor was re-defined with even margins from the gross target volume (GTV), and the actual plan overlaid the re-defined PTV. The correlations between the tumor response rate during chemoradiotherapy and a2er chemoradiotherapy, and the dose distribution parameters (D95, V95, mean tumor dose and homogeneity index), total dose and GTV, were evaluated.Results: Median overall survival was 15.5 months and the two-year survival 42.3%. At first recurrence, radiation-field recurrence, distant metastases and simultaneous recurrence were developed in 35.5%, 41.9% and 9.7% of the cases, respectively. The dose distribution parameters were generally favorable and were not related with tumor response rate. The tumor response rate a2er chemoradiotherapy was correlated with the residual GTV at second simulation (g=-0.627, p<0.001) and the tumor response rate during chemoradiotherapy (g=0.541, p=0.003).Conclusion: Minimal correlation was found between the dose distribution parameters that were over the minimal dose requirement and tumor response in NSCLC with concurrent chemoradiotherapy. The small residual volume during chemoradiotherapy could indicate good tumor response a2er chemoradiotherapy.

Background: Colorectal cancer is the most common gastrointestinal cancer and the fourth leading cause of death in the world. This study aimed to investigate and compare dosimetric differences in radiation therapy for rectal cancer in two supine and prone positions.Methods: In a cross-sectional study in Milad Hospital in Isfahan, the CT scan data of 30 patients who are candidates for radiation therapy for rectal cancer were sent to the treatment design software. The target organ PTV (Planning Target Volume) and the organs at risk including the bowel bag and the bladder were contoured by the radio-oncologist. The design of three-dimensional conformal radiotherapy (3D_CRT) was designed using 3 and 4 field methods and 18 megavolt energy. Finally, using the dose-volume distribution curve dose-volume histogram (DVH), the dosimetry of the target organs and the organs at risk were discovered and converted by assimilation.Findings: The average dose that will receive by the bowel bag and bladder in the prone position in the 3-field method was significantly lower than the other studied methods. In addition, the position of the 3-fields supine delivers a higher dose to the organs at risk than the 3-fields prone. However, organs of the four fields in supine position will receive a higher dose compared to the other fields.Conclusion: In radiation therapy of rectal cancer, due to the improvement of the coverage of the target volume and better dose design, it is suggested than the treatment with the 3-field in position prone.