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.

Background: This study aims to evaluate and compare THREE-DIMENSIONAL CONFORMAL RADIOTHERAPY ((3D-CRT)) versus Helical Tomotherapy (HT) based on treatment planning and selection of the most appropriate method to reduce side effects. Materials and Methods: Treatment planning was performed on images of 20 patients with head and neck cancer with lymph node involvement by HT and (3D-CRT) techniques in Seyed Al-Shohada hospital, Isfahan, Iran. The quality of target coverage, the exposure of normal tissue, and radiation delivery efficiency in two studied methods were compared. Results: Tomotherapy showed significant improvement over (3D-CRT) in terms of D2%, D50% Dmean, V95%, CI (conformity index), and HI (homogeneity index) for PTV (planning target volume) and in terms of D2%, D98%, Dmean, V95%, CI and HI for PTV Nodal. The mean dose received by 98% of PTV (D98%) increased in HT compared to (3D-CRT). Whereas, higher doses received in organs at risk (OARs) in 3DCRT compared to HT. Conclusion: Results showed improvements in target quality for HT over (3D-CRT), including dosimetric coverage of target volumes, homogeneity and conformity indices, and reduction of the volume of cold and hot spots. Tomotherapy also performed better than that of (3D-CRT) in OARs. Overall, with the satisfactory results obtained here, HT technique has considerable promise for treating head and neck cancers with the involvement of regional lymph nodes.

Introduction: some cardio-pulmonary complications, such as lung pneumonia in the RADIOTHERAPY treatment of breast cancer are associated with several factors including the amount of irradiated lung volume. Therefore in this study, the determining factors in irradiated lung volume have been investigated.Methods: In this study, 48 patients with early breast cancer treated with 3D CRT radiation, were chosen. All ORS and PTV were contoured based on the RTOG atlas. CLD, MLD and GPD parameters were measured and their relationship with irradiated lung volume percentage was studied by DVH curves.Results: The correlation between CLD and GPD with a percentage of irradiated lung volume in the tangential fields was linear. For example, CLD of right lung CLD equal to 15, 25 and 35 mm accounted for 10%, 17% and 24% of lung volume in Tangential fields, respectively.Conclusion: The correlation between CLD and lung volume in tangential fields for the left and right lung was significant. With an increase of one unit in the CLD, on average we expect that left and right lungs volume is increased 2% and 3.2%, respectively.

Introduction: Radiation-induced secondary primary cancer is one of the significant late side effects and an undesired outcome of RADIOTHERAPY that can be observed in long-term cancer survivors. The present study aimed to estimate the risk of second cancer risk after THREE-DIMENSIONAL CONFORMAL RADIOTHERAPY (3DCRT) and intensity modulated RADIOTHERAPY (IMRT) for early stage prostate cancer patient. Material and Methods: In this study, 10 patients with early stage prostate cancer have been chosen. Threedimensional CONFORMAL RADIOTHERAPY (3DCRT), intensity-modulated RADIOTHERAPY (IMRT) plans were designed. The organ equivalent dose (OED) was calculated based on linear, linear-exponential, and plateau dose-response models. The Second cancer risks (SCR) were estimated by Excess absolute risk (EAR). Results: The target dose coverage parameters were significantly improved in IMRT compared to 3DCRT. The rectum and bladder mean dose DMean, V50Gy% and V40Gy % were significantly decreased with IMRT. The maximum dose (DMax), DMean, V30Gy % and V20Gy % for head of femurs significantly decreased with IMRT plans. However, the colon DMean significantly increased with in IMRT compared with 3DCRT. The IMRT plans were decreased SCR for the rectum by 10%, 26. 6% and 19. 5% for linear, plateau and linearexponential dose-response models respectively. The bladder second cancer risk was decreased by 14% with linear dose-response model in comparison to 3DCRT plans. However, the second cancer risk for colon was significantly increased in average by 91. 2% with IMRT plans. Conclusion: IMRT technique demonstrated a clear advantage in dose coverage, conformity, and homogeneity over 3DCRT and was superior in terms of OAR-sparing. The Second cancer risk for in field organs (rectum and bladder) was decreased with IMRT compared 3DCRT plan.

Background: RADIOTHERAPY plays a major role in the treatment of the cervical cancer. Objective: Dosimetric comparison of intensity-modulated radiation therapy (IMRT) with THREE-DIMENSIONAL CONFORMAL radiation therapy (3DCRT) in cervical cancer treatment was performed by modifying the beams arrangements to achieve better organ at risk (OAR) sparing. Material and Methods: The analytical evaluation study was made by modifying the IMRT plan, subtracting the rectal volume from planning target volume (PTV), and applying the field-in-field technique in 3DCRT. Eight patients in various cervical cancer stages, from I‒, III, were inducted for this investigation. The prescribed dose was 5000 cGy in 25 fractions. For all cases, both IMRT and 3DCRT plans were generated. For PTV and OARs, dose volume histogram (DVH) comparative analysis was carried out. For safety checks and quality control, pre-treatment verification of all the plans was performed using an indigenously developed pelvic phantom (for IMRT and 3DCRT) and gamma analysis with Delta4 phantom (for IMRT). Results: This study indicated that IMRT can treat cervical cancer more efficiently with less damage to OARs as compare to 3DCRT. Conclusion: In this study, we observe that the IMRT plans with subtracting rectal volume achieve better OAR sparing.

Background: The aim of this study was to compare the treatment plans of three techniques namely THREE-DIMENSIONAL CONFORMAL RADIOTHERAPY (3DCRT), Electronic tissue compensator (ECOMP) based planning and Volumetric Modulated Arc Therapy (VMAT). Material and Methods: The planning goal was set to cover 95% of the planning target volume with 95% prescription dose for the dose plan of 40 Gy in 16 fractions. Treatment techniques with improved dose homogeneity, optimum skin dose, lung dose (V20Gy) and contralateral breast dose were used as the criteria to select the optimized treatment plan. The treatment planning time and the number of monitor units (MU) required to execute the plan were also taken into consideration. Result: PTV coverage (V95%) for the patient of ca-right breast and the ca-left breast was superior in VMAT plans. Ipsilateral lung (V5Gy %) showed significant dose reduction in ECOMP plans compared to 3DCRT and VMAT plans. Similarly, for the heart and contralateral lung, the mean doses were least in ECOMP plans. Dose homogeneity Index (HI) and Dose conformity Index (CI) was better in ECOMP plans compared to 3DCRT, but VMAT plans were superior to both the other techniques. The skin surface dose was less in VMAT plan. Conclusion: VMAT has high CI as well as HI but at the cost of higher OAR doses (lung and heart) and large treatment planning time. For a busy center, ECOMP can be a good choice of treatment technique which can optimize the OAR doses and treatment planning time but for dose homogeneity and conformity, VMAT is superior to others.

Introduction: Heterogeneity correction is an important parameter in dose calculation for cancer patients where it may be cause inaccuracy in dose calculation as a result of different densities of patients. This study studied the impact of dose calculation of breast cancer patients with and without heterogeneity correction. Material and Methods: Twenty breast cancer patients were treated with THREE-DIMENSIONAL CONFORMAL RADIOTHERAPY(3DCRT). Dose calculations were performed using two modes: Fast Photon mode for homogeneity and Fast Photon Effective Path length for heterogeneity with two photon energies. Monitor Units(MU), Modulation Factor, Dose Volume Histograms(DVH) and quality indices were used to evaluate the effect of heterogeneity correction on dose calculation and investigate the mechanism of this effect in the low and high energies. Results: Heterogeneity correction compared to without it showed significant reduction in MU and modulation factor at 6MVand 10MV (p<0. 05). Dosimetric parameters derived from DVH were significantly lower for Planning Target Volume (PTV) with homogeneity versus heterogeneity (p<0. 05) as D95% (95. 1%vs93. 7%) and V95%(95. 3%vs89%) for 6MV while max Dose and D2 increased. Also the dose for organs at risk exhibited an increase with heterogeneity correction. Quality indices were be worst with heterogeneity correction with a significant difference (p <0. 05). The differences between the dose with heterogeneity correction and without it in 6MV and 10MV were as follows: Δ D95% (4. 4%vs3. 4%; P=0. 001) and Δ V95%(4. 76%vs4. 5%; P=0. 001). Conclusion: non-use of the heterogeneity correction can be cause to deliver under or overdose dose to the target volume. Tissue heterogeneity correction had an impact on dose calculation for breast cancer patients and this impact was more effective for the low energy.

Introduction: The purpose of this study is to evaluate and compare treatment plan quality metrics for postmastectomy breast cancer patients using 3-Dimensional CONFORMAL RADIOTHERAPY (3DCRT) and intensitymodulated RADIOTHERAPY (IMRT) planning techniques. Material and Methods: The current study included 50 postmastectomy breast cancer patients out of which 24 were planned with 3DCRT and 26 with IMRT technique. Treatment plan quality metrics, namely homogeneity index (HI), conformity index (CI), conformation number (CN), uniformity index (UI) and spillage index (R50), volume receiving 110% and 95% of the prescribed dose (V110% and V95%) were calculated and compared for the two planning techniques. Results: IMRT plans have better conformity, homogeneity indices, and lower V110% than 3DCRT plans with an almost similar R50% and V95%. Conclusion: Quantitative values of RADIOTHERAPY treatment plan quality metrics for the target are found in favour of the IMRT technique rather than 3DCRT. Implementation of these five parameters is helpful for evaluating treatment plans along with slice by slice and DVH analysis.

Background: To analyze the dosimetric and radio biologic advantages between intensity modulated RADIOTHERAPY (IMRT) and 3 dimensional CONFORMAL RADIOTHERAPY (3DCRT) and selection of optimal photon energy for IMRT treatments.Materials and Methods: 24 patients with localized prostate carcinoma were planned for 3DCRT and IMRT techniques. Radiation dose of 54 Gy with 2 Gy/fraction, was planned to Planning target volume (PTV1) (prostate+seminal vesicle+1 cm margin) and 72 Gy to PTV2 (prostate+1 cm margin) respectively. 3DCRT planning was done using 15 MV photon beam while IMRT plans were created using 6 MV and 15MV photons. Treatment plans were analyzed using mean, median, dose maximum and cumulative dose volume histogram for PTV1, PTV2, bladder, and rectum. Tumor control probability (TCP) was calculated for prostate. Normal tissue complication probability (NTCP) was calculated for bladder, rectum, and head of femur. Results: Mean dose to prostate was 72.79±0.18 Gy for IMRT 15 MV, 72.16±0.27 Gy for 3DCRT and 72.48±0.19 Gy for IMRT 6 MV. TCP was greater for IMRT 15 MV followed by IMRT 6 MV. The mean value of NTCP was significantly lower (p=0.0015) for IMRT 6 MV compared to 3DCRT for rectum while for bladder all were comparable. Conclusion: IMRT techniques shows superiority in sparing surrounding critical organs, thus reducing normal tissue complication rates while maintaining the same or higher tumor control probability. No significant difference was observed between IMRT 6 MV and IMRT 15 MV techniques.

Background: External beam RADIOTHERAPY (EBRT) is mainstay of treatment in patients with locally advanced cervical carcinoma (LACC). Three dimensional CONFORMAL RADIOTHERAPY (3DCRT) and intensity modulated RADIOTHERAPY (IMRT) are mainly used in EBRT. However which one is superior is still controversial. Materials and Methods: Forty patients of LACC treated with IMRT were selected for this study.3DCRT plans were also created for all the patients.3DCRT and IMRT plans were compared on the basis of planning target volume (PTV) coverage, dose to normal organs, homogeneity index (HI) and conformity index (CI95%).Results: In both the techniques 99% of PTV was covered with more than 96% of prescribed dose (PD). D15, D35 and D50 (Dose to 15%, 35% and 50% volume respectively) for bladder was reduced by 2.09%, 14.623% and 32.57% and for the rectum it was reduced by 7.46%, 23.82% and 43.68% in IMRT compared to 3DCRT. V45 (volume receiving 45 Gy) in case of bowel were found to be much less in IMRT in comparison to 3DCRT. Insignificant difference found between doses to femoral heads in IMRT and 3DCRT. The CI95% in IMRT plans was found much better than that in 3DCRT whereas HI in both the techniques were found almost same.Conclusion: IMRT significantly reduced the irradiated volume of OAR and improved dose conformity in the PTV compared to that by 3DCRT. So, it can be concluded that IMRT should be chosen as preferred technique for the EBRT of LACC with proper immobilizing devices and imaging.