NULL

Background: The quality assurance of 3D treatment planning system (TPS)will be investigated by different things such as beam configuration, dose calculation and plane evaluation which uses dose volume histogram analyzes. Material and method: the study was performed by XIO TPS (version 4.3.3) available at South Egypt Cancer Institute (SECI). This TPS employs two different 3D algorithms (Clarkson (CLK) and Fast Fourier Transform Convolution (CON)). Relative dose calculation (RDC) in terms of percentage depth dose (PDD) and off axis beam profiles (OAR) and absolute dosecalculation (ADC) in terms of dose and output factor were used and compared with the measured one using ionization chambers with water or solid phantoms in medical linear accelerator linac (Siemens Mevatron MD2).Two photon energies 6MV and 15MV were studied using field sizes of 10×10cm2 and 25×25cm2 for open field. Results: The OAR and PDD are divided into regions each of these having a tolerance limit of the accuracy acceptable. The large point of deviation appeared in field size 25×25cm2 at energy 15MV in outer regionδ4 of OAR. This region recorded the largest deviation than the others regions. In PDD curves haven’t any deviation.Larger deviations were observed with CLK algorithm compared to CON algorithm. 20 points out of criteria were observed in the RDC of a large field size 25×25cm2, while 16 points were out of criteria in the field size 10×10cm2. Conclusion: This work presents a feasibility and performance of quality assurance tasks the TPS for external photon beam

Background: The quality assurance of 3D treatment planning system (TPS)will be investigated by different things such as beam configuration, dose calculation and plane evaluation which uses dose volume histogram analyzes. Material and method: the study was performed by XIO TPS (version 4.3.3) available at South Egypt Cancer Institute (SECI). This TPS employs two different 3D algorithms (Clarkson (CLK) and Fast Fourier Transform Convolution (CON)). Relative dose calculation (RDC) in terms of percentage depth dose (PDD) and off axis beam profiles (OAR) and absolute dosecalculation (ADC) in terms of dose and output factor were used and compared with the measured one using ionization chambers with water or solid phantoms in medical linear accelerator linac (Siemens Mevatron MD2).Two photon energies 6MV and 15MV were studied using field sizes of 10×10cm2 and 25×25cm2 for open field. Results: The OAR and PDD are divided into regions each of these having a tolerance limit of the accuracy acceptable. The large point of deviation appeared in field size 25×25cm2 at energy 15MV in outer regionδ4 of OAR. This region recorded the largest deviation than the others regions. In PDD curves haven’t any deviation.Larger deviations were observed with CLK algorithm compared to CON algorithm. 20 points out of criteria were observed in the RDC of a large field size 25×25cm2, while 16 points were out of criteria in the field size 10×10cm2. Conclusion: This work presents a feasibility and performance of quality assurance tasks the TPS for external photon beam

A quarter-wavelength coaxial cavity with a longitudinal radio-frequency power supply was fabricated and tested. The cavity was designed as a pre-buncher for a thermionic triode-type radio-frequency gun of a mid-infrared free electron laser facility. The triode structure was formed to ensure the reduction of the back-bombarding effect, which usually appears in thermionic radio-frequency guns. The coaxial cavity was tested using a tungsten dispenser cathode. From the results of the cold test, a cavity voltage of about 25 kV can be attained, which corresponds to designed characteristics. In contrast, the hot test showed a sudden drop in voltage, resulting in an unstable operation. The small dimensions of the cavity caused some low-field effects, which led to multipactoring. In this paper, we report the tested characteristics of the pre-bunching cavity.

A quarter-wavelength coaxial cavity with a longitudinal radio-frequency power supply was fabricated and tested. The cavity was designed as a pre-buncher for a thermionic triode-type radio-frequency gun of a mid-infrared free electron laser facility. The triode structure was formed to ensure the reduction of the back-bombarding effect, which usually appears in thermionic radio-frequency guns. The coaxial cavity was tested using a tungsten dispenser cathode. From the results of the cold test, a cavity voltage of about 25 kV can be attained, which corresponds to designed characteristics. In contrast, the hot test showed a sudden drop in voltage, resulting in an unstable operation. The small dimensions of the cavity caused some low-field effects, which led to multipactoring. In this paper, we report the tested characteristics of the pre-bunching cavity.

The common radioactivity substances (Ra-226, Th-232 and K-40) were measured in oil ash samples collected from the Assiut Thermal Power Plant (ATPP) in Egypt by gamma spectrometry. Outcomes were contrasted with those from past investigations. The activity concentrations have declined from past investigations by around 58 %, 77 % and 95 % for 226Ra, 232Th, and 40K, respectively. The reason for this extreme decrease will be discussed. A positive with moderate correlation between 226Ra and 232Th, and between 226Ra and 40K in the examined ash samples was identified from the observed correlation R2 of 0.6 and 0.4 respectively. All estimations of radiological risk indices demonstrate a generous decrease; however, they remain more than the world reference. For instance, the radium equivalent activities (Raeq) and the hazard indices are considerably more than 370 Bq kg-1 and unity, respectively. Mean absorbed dose rate was 3250 nGy h-1, which is around fifty-five times more than the world reference estimation of 59 nGy h-1; relating annual external effective dose is assessed to be at 3.9 mSv y-1, which is around fifty-five times higher than what is found in regions of common foundation radiation 0.07 mSv y-1.

The common radioactivity substances (Ra-226, Th-232 and K-40) were measured in oil ash samples collected from the Assiut Thermal Power Plant (ATPP) in Egypt by gamma spectrometry. Outcomes were contrasted with those from past investigations. The activity concentrations have declined from past investigations by around 58 %, 77 % and 95 % for 226Ra, 232Th, and 40K, respectively. The reason for this extreme decrease will be discussed. A positive with moderate correlation between 226Ra and 232Th, and between 226Ra and 40K in the examined ash samples was identified from the observed correlation R2 of 0.6 and 0.4 respectively. All estimations of radiological risk indices demonstrate a generous decrease; however, they remain more than the world reference. For instance, the radium equivalent activities (Raeq) and the hazard indices are considerably more than 370 Bq kg-1 and unity, respectively. Mean absorbed dose rate was 3250 nGy h-1, which is around fifty-five times more than the world reference estimation of 59 nGy h-1; relating annual external effective dose is assessed to be at 3.9 mSv y-1, which is around fifty-five times higher than what is found in regions of common foundation radiation 0.07 mSv y-1.

In this study, the natural radionuclides in soil and sand have been measured by using high purity germanium (HPGe) detector. While, radon exhalation rate has been measured by Alpha GUARD. The data analysis is performed to determine 226Ra, 232Th, and 40K activity concentrations in addition to 222Rn exhalation rate. The values of radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), and absorbed dose rate were ranged from 46.46 to 124.16 Bq⋅kg−1, 0.07 to 0.33 Bq⋅kg−1, 0.09 to 0.42 Bq⋅kg−1, and 13.24 to 58.37 nGy⋅h−1 respectively in all samples. The area and mass exhalation rates were increased from 9.16 ± 2.83 to 16.18 ± 2.83 Bq⋅m−2⋅h−1 and 1.8 ± 1.34 to 11.35 ± 0.98 Bq⋅kg−1⋅h−1 respectively.

Determination of the full-energy peak efficiency of a detection system is significant in the activity calculation of the measured radioactive samples. In this work, we present an experimental method to determine the absolute efficiency calibration of a NaI(Tl) detector, considering that a standard source of interest is unavailable and by using the known specific activity of a standard sample measured using a HPGe detector. The efficiency of a gamma-ray spectrometer that consists of a coaxial HPGe detector is calculated using Canberra ISOCS/LabSOCS software and a fabricated calibration source. To validate our method, environmental samples (rock and soil samples) were analyzed on both the detectors. The obtained activity concentrations were checked by means of the IAEA proficiency test procedure. The performance criteria evaluation results were found to be ‘Acceptable’ for all the analytical determinations of all the radionuclides under study, except for the samples with low activity (15 Bq kg−1 and 10 Bq kg−1 for 226Ra and 232Th, respectively). The precision of the low-activity samples was not considered ‘Acceptable’ as the results were slightly inaccurate; in this case, the results were considered as ‘Warning’ because the relative bias (RB) was less than the maximum acceptable bias (MAB).

Determination of the full-energy peak efficiency of a detection system is significant in the activity calculation of the measured radioactive samples. In this work, we present an experimental method to determine the absolute efficiency calibration of a NaI(Tl) detector, considering that a standard source of interest is unavailable and by using the known specific activity of a standard sample measured using a HPGe detector. The efficiency of a gamma-ray spectrometer that consists of a coaxial HPGe detector is calculated using Canberra ISOCS/LabSOCS software and a fabricated calibration source. To validate our method, environmental samples (rock and soil samples) were analyzed on both the detectors. The obtained activity concentrations were checked by means of the IAEA proficiency test procedure. The performance criteria evaluation results were found to be ‘Acceptable’ for all the analytical determinations of all the radionuclides under study, except for the samples with low activity (15 Bq kg−1 and 10 Bq kg−1 for 226Ra and 232Th, respectively). The precision of the low-activity samples was not considered ‘Acceptable’ as the results were slightly inaccurate; in this case, the results were considered as ‘Warning’ because the relative bias (RB) was less than the maximum acceptable bias (MAB).