ABSTRACT
Background: Accurate small radiation field dosimetry is essential in modern radiotherapy techniques such as stereotactic radiosurgery [SRS] and intensity modulated radiotherapy [IMRT]. Precise measurement of dosimetric parameters such as beam profile, percentage depth doses and output factor of these beams are complicated due to the electron disequilibrium and the steep dose gradients. In the present work the MAGIC polymer gel was used for dosimetry of small circular photon beams. The results of MAGIC were compared with EBT2 measurements and Monte Carlo [MC] calculations. Materials and Methods: Experimental measurements were made by mentioned dosimeters in four small field sizes 5, 10, 20 and 30 mm. The BEAMnrc code based on EGSnrc was used for simulation to calculate dosimetric parameters at these small fields. The phantoms were irradiated in a 6 MV photon beam Varian 2100C linear accelerator at SSD=100 cm. gel readout performed by 3 Tesla MRI scanner. Results: The results showed that the Percent depth dose [PDD] values measured and calculated by EBT2 film and MC had maximum local differences 4% and 5% with PDD values measured by MAGIC for field size of 5mm respectively. These differences decreased for larger field sizes. The measurements of output factor and penumbra [80%-20%] and [90%-10%] showed good agreement between the measurements and MC calculation. Conclusion: This study showed that the MAGIC polymer gel based on high resolution MRI images is useful detector for small field dosimetry but its agreement with MC is less than agreement of EBT2 film with MC
ABSTRACT
Background and Objective: Genuvarum is considered as one of the risk factors for the incidence of osteoarthritis. This study was done to compare the knee joint muscles activity during single leg drop landing from different heights among men with genu varum and men with normal knee
Methods: This case - control study was done on 20 male students with genu varum deformity and 20 male students with normal knee. Genu varum deformity was measured by a kolis and goniometer. Muscle activity of lower limb was recorded with electromyography
Results: There was significant difference in muscles activity of medialis gastrucnemius, peroneus longus, biceps femoris and gluteus medius in cases and controls [P<0.05], while no significant difference was observed in other muscles
Conclusion: The changes in the knee normal structure might affect daily activities and possibly lead to in injuries due to physical training
ABSTRACT
The purpose of this study was to compare the radiographic grading scales osteoarthritis, knee pain, signs and movement dysfunctions related to osteoarthritis in daily, sport and recreational activities and also the quality of life between ex-elite track and field athletes and the non-athletes. Thirty ex-elite male track and field athletes were purposefully selected and divided into two equal groups [n=15]. The clinical and radiological methods [Kellgren-Lawrence] and a global and domestic questionnaire of the knee injury and osteoarthritis outcome score [KOOS] were used to diagnose the disease. Results showed a significant lower mean for movement dysfunctions in sport and recreational activities between athletes and non-athletes [P=0.02]. Despite a 30% difference in the mean radiographic grading for osteoarthritis in athletes compared to the non-athletes, the difference was not statistically significant [P=0.90]. Moreover, the lower mean values for knee pain, signs, movement dysfunctions in daily activities and the quality of life in athletes were 10% [P=0.27], 10% [P=0.09], 12% [P=0.13] and 4% [P=0.90], respectively compared to non-athletes, however, the difference was not statistically significant. Participating in track and field competitions at the professional level may improve the movement function of ex-elite athletes
ABSTRACT
In order to quantify effects of ultrasound irradiation parameters under therapeutic condition, especially sonodynamic therapy, it is initially necessary to evaluate inertial cavitation activity in vitro conditions; therefore, in this study, the effect of 1 MHz low level ultrasound based on OH radicals generated by acoustic inertial cavitation in aqueous solution was monitored by their reaction with terephthalic acid [TA] to produce fluorescent 2-Hydroxyterephthalate acid [HTA] by spectrofluorometry method [Terephtalic acid dosimetry]. The study was designed to measure hydroxyl radicals in a field near to 1 MHz sonotherapy probe in progressive mode and low level intensity. The effect of ultrasound irradiation parameters [1MHz] containing duty factor, mode, intensity ultrasound and, time sonication in hydroxyl radical production have been considered. After preparation of solution of dosimetry and plotting calibration curve of spectrofluorescence, the effect of mode of sonication [continuous and pulsating], duty factor [20-80%], intensity [0-2 W/cm[2], with step of 0.5 W/cm[2]], and sonication time [0-60min with step time of 10min] without increasing temperature to more than 3°C to determine the effective exposure in low level ultrasound were evaluated. The fluorescence intensity of TA solution before and after irradiation, in all cases was measured, and the results were reported as Mean +/- Standard Deviation [SD]. The result of experiments related to sonication mode for 1MHz ultrasound irradiation [2 W/cm[2]] show that continuous mode of sonication is 29% higher fluorescence intensity than the pulse mode in 80% duty cycle for sonodynamic therapy. With compensation of irradiation time for 1MHz sonication in different duty cycles, fluorescence intensity in continuous mode is 22% higher than the pulse mode in average. The amount of hydroxyl radicals production versus ultrasound intensity, and sonication time show with increasing intensity or sonication time in continuous mode, the hydroxyl radical production is linearity increased [R=0.99]. The results show that the terephthalic acid dosimetry is suitable for detecting and quantifying free hydroxyl radical as a criterion of inertial cavitation production over a range of condition in medical ultrasound fields