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Background and purpose: Pain relief is one of the major parts in midwifery. One method of medication for pain relieving in labor, is using the Entonox gas. The present study is conducted to compare the continuous and intermittent use of Entonox gas in the reduction of labor pain. Material and Methods: This study is a clinical trial conducted on 100 pregnant women hospitalized in Shahidan Mobini Hospital in Sabzevar (2013). The research samples were selected based on purposing sampling method and were randomly divided into two groups using Entonox. Research tools included interview forms, registration forms, medical information derived from the parturient case and visual pain scale. Statistical analyses were performed by Spss 17 software, statistical t-test and chisquare test. Results: The average pain intensity in total active phase in intermittent group was 6.2±2.4 and in continuous group 5.4±2.5 which showed no significant difference between the two groups (P= 0.127). The average pain intensity second stage of labor in intermittent group was 7.8±2.8 and in continuous group 6.5±3.7 which showed no significant difference between the two groups (P= 0.06). There was no significant statistical difference between two groups in the first and the fifth minute Apgar score (P>0.05) Conclusion: It seems that the application of Entonox in continuous form is a better way to control labor pain than the intermittent method which is the conventional method of using Entonox, and has no specific side effects for both the mother and the baby.

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Background and purpose: Nowadays, in developed countries, the economic profits of recycling and its role in waste reduction and disposal costs is well recognized. In this study, the economic aspects of dry solid waste recycling were evaluated in Shiraz, Iran.

Materials and methods: A descriptive cross-sectional study was conducted in Shiraz in which data was collected through field observations, interviews with officials of municipal utilities and investigating the documents in the organization. Then, the economic benefits of different recycling rates including 15% (current), 50% and 80% were evaluated.

Results: The recycling rate of  waste paper, cardboard, glass, nylon and plastic carrier bags, disposable plastic containers, PET, other types of plastic, disposable metallic containers, and other types of metals were 23%, 12%, 8%, 2.5%, 8%, 13%, 13%, 11%, and 12%, respectively. The total economic benefits of recycling in terms of current recycling (15%), desirable recycling (50%) and ideal recycling (80%) rates were calculated as 11527, 39869, and 63791 million Rials per year, respectively.

Conclusion: Only 15% of dry solid waste is recycled in Shiraz. The economic benefits from recycling could increase to 8-18 times of the current benefit with a 10 to 20 year proper planning and upgrading the current recycling program.

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Background and purpose: Beam shaper is a type of applicator used in conjunction with the intraoperative electron radiotherapy. This study aimed at quantitative evaluation of the photon contamination of this applicator using Monte Carlo simulation.

Materials and methods: In this experimental study, at first the head of LIAC accelerator was simulated along with the beam shaper applicator using MCNPX Monte Carlo code. Validity of the simulated model was evaluated by comparing the percentage depth dose curves obtained by Monte Carlo simulation and practical dosimetry. Finally, the photon contamination at different clinical field sizes and electron energies was quantitatively determined.

Results: The results showed that by increase in field size, the photon contamination of the beam shaper applicator was considerably decreased. Furthermore, increment of electron energy could increase the photon contamination.

Conclusion: Increasing the photon contamination at the phantom surface by increment of electron energy and decrement of field size can be attributed to increasing the probability of electron interaction with the steel blades of the beam shaper and production of bremsstrahlung radiation at higher energies. Due to the photon contamination, employing the beam shaper applicator can increase the surface dose.

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Background and purpose: Dose calculations in trachea HDR brachytherapy treatment planning systems are greatly based on TG-43 protocol in which, all materials including air inside trachea are treated the same as water. The aim of this study was to survey the effect of air on dose calculations of Flexiplan treatment planning system in trachea HDR brachytherapy.

Materials and methods: To evaluate the effect of air inhomogeneity, a neck-equivalent plexiglass cylindrical phantom was used. Dose measurement was carried out by EDR2 film. Treatment planning and irradiation were performed using Flexiplan software and Flexitron brachytherapy system, respectively.

Results: The results showed that considering the air inside trachea as water increases the absorbed dose by 12% which can lead to increment of patient dose.

Conclusion: A significant difference was seen between dosimetry results in the two conditions. Therefore, taking the air similar to water has a considerable effect on dose calculations of trachea HDR brachytherapy and accuracy of treatment plan performed.

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Breast cancer is considered as one of the main causes of cancer death in women. Early diagnosis and treatment, especially by modern technologies play major roles in management of breast cancer. Radiation therapy is known as one of the main treatment options for breast cancer. Nowadays, 3D printing technology is also used to rapidly construct objects with high quality. Many studies have shown the positive effects of this technology on the results of cancer radiation therapy. The aim of this study was to review the application of 3D printing technology in treatment of breast cancer by mega voltage electron and photon beams, including bolus, applicators, immobilizer devices, and compensators. Creating personalized treatment devices by 3D printing technology reduces treatment errors, therefore, the prescribed dose is increased in the treatment area and subsequently improves treatment outcomes. In spite of the valuable benefits of this technology, there are some disadvantages such as size limitations and the number of materials used for printing. Indeed, recent studies are trying to fix the shortcomings of 3D printing technologies in clinical applications.