scholarly journals Monitoring beam-quality constancy considering uncertainties associated with ionization chambers in Daily QA3 device

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246845
Author(s):  
Su Chul Han ◽  
Jihun Kim ◽  
Min Cheol Han ◽  
Kyung Hwan Chang ◽  
Kwangwoo Park ◽  
...  
Keyword(s):  
Beam Quality ◽  
Energy Levels ◽  
Repeated Measurements ◽  
Secondary System ◽  
Ionization Chambers ◽  
X Ray ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Daily Energy

This study evaluates the changes occurring in the X-ray energy of a linear accelerator (LINAC) using a Daily QA3 detector system. This is accomplished by comparing the Daily QA3 results against those obtained using a water phantom. The X-energy levels of a LINAC were monitored over a duration of 1 month using the Daily QA3 system. Moreover, to account for the uncertainty, the reproducibility of the Daily QA3 ionization-chamber results was assessed by performing repeated measurements (12 per day). Subsequently, the energy-monitoring results were compared with the energy-change results calculated using the water-phantom percentage depth dose (PDD) ratio. As observed, the 6- and 10-MV beams experienced average daily energy-level changes of (-0.30 ± 0.32)% and (0.05 ± 0.38)%, respectively, during repeated measurements. The corresponding energy changes equaled (-0.30 ± 0.55)% and (-0.05 ± 0.48)%, respectively, when considering the measurement uncertainty. The Daily QA3 measurements performed at 6 MV demonstrated a variation of (2.15 ± 0.81)% (i.e., up to 3%). Meanwhile, the corresponding measurements performed using a water phantom demonstrated an increase in the PDD ratio from 0.577 to 0.580 (i.e., approximately 0.5%). At 10 MV, the energy variation in the Daily QA3 measurements equaled (-0.41 ± 0.82)% (i.e., within 1.5%), whereas the corresponding water phantom PDD ratio remained constant at 0.626. These results reveal that the Daily QA3 system can be used to monitor small energy changes occurring within radiotherapy machines. This demonstrates its potential for use as a secondary system for monitoring energy changes as part of the daily quality-assurance workflow.

Depth dose measurement in water phantom for two X-ray energies (6MeV and 10MeV) in comparison with actual planning

2019 ◽  
pp. 1689-1693
Author(s):  
Raghdah H. Hasan ◽  
Samar I. Essa ◽  
Manwar A. AL-Naqqash
Keyword(s):  
Soft Tissue ◽  
Field Size ◽  
Vertical Position ◽  
Dose Measurement ◽  
High Similarity ◽  
X Ray ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Different Depths

The purpose of this study is to measure doses delivered at different depths in water phantom at vertical position in comparison with the actual planning in order to verify the dose delivered to the tumor in addition to the measurement of the effect penumbra dose to assess the dose leaking to the healthy soft tissue.      Percentage depth dose (PDD) values was measured at field sizes (5×5,10×10,15×15, and 20×20) cm2, and the depth dose was measured between (0-16) cm deep at 4cm intervals, for both energies 6 MeV and 10 MeV X-ray beam. Other readings were taken at different distances 1cm and 2cm outside of the actual beam in orthogonal directions at depth of 4 cm. These measurements were designed to measure the penumbra dose produced outside the central beam.      Results show that the high similarity between water phantom and actual tissue for this reason water is taken as phantom for Quality Assurance (QA) and calculation the depth dose. The similar results may appear strange as the actual planning depth dose is taken in the chest wall where there is bone and soft tissue. The increase in the field size, increases the percentage of surface dose, this could be caused by an increase in the amount of scattering in the larger fields. There is almost no difference in depth dose between homogenous and non homogenous planning also similar to the water phantom. Because of higher photon energy 6MeV and 10MeV the bone has no influence in absorption from the soft tissue. A slight change in the depth dose with increase in the field size may be caused by the scattered radiation.

scholarly journals Measurement of Percentage Depth Dose (PDD) for 6 MeV in water phantom and homogenous actual planning

2018 ◽  
Vol 16 (37) ◽  
pp. 1-6
Author(s):  
Samar I. Essa
Keyword(s):  
Ionizing Radiation ◽  
Clinical Medicine ◽  
Absorbed Dose ◽  
Field Size ◽  
X Ray ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Different Depths ◽  
The Relationship

Radiotherapy is the branch of clinical medicine concerned with the application of ionizing radiation in the treatment of disease. And it is used to killing of cancer cells in a tissue using ionizing radiation while keeping the sparing of healthy cells at acceptable level. X-ray beams are used to deposit absorbed dose at depth within a patient at the site of the tumor. The aim of this work is studying the relationship between the depth dose and the field size in water phantom and homogenous actual planning. In our work, the dose distribution at different depths (zero-18 cm) deep at1cm interval treated with field size (10×10 and 20×20) cm2 were studied.Results show that high similarity between water phantom and actual planning for this reason water is taken as phantom for Quality Assurance (QA) and calculation the depth dose. When increasing the field size, the percentage of surface dose increases that this could be caused by an increase of the amount of scattering in the larger fields.Conclusion: There is almost no difference in depth dose between homogenous planning and water phantom.

Experimental measurements and Monte Carlo modelling of the XSTRAHL 150 superficial X-ray therapy unit

2014 ◽  
Vol 14 (1) ◽  
pp. 43-55
Author(s):  
Fayez H. H. Al-Ghorabie
Keyword(s):  
Monte Carlo ◽  
Theoretical Calculations ◽  
Beam Quality ◽  
Patient Treatment ◽  
Experimental Measurements ◽  
Monte Carlo Code ◽  
X Ray ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Good Agreement

AbstractBackgroundSuperficial X-ray therapy units are used for the treatment of certain types of skin cancer and some severe dermatological conditions. The performance assessment and beam characteristics of the superficial unit are very important to ensure accurate dose delivery during patient treatment. Both experimental measurements and Monte Carlo calculations can be used for this purpose.PurposeThis study aims to investigate whether it is possible to reproduce experimentally measured data for the XSTRAHL 150 superficial X-ray unit with simulations using the BEAMnrc Monte Carlo code.Materials and MethodsThe experimental procedure applied in this study included the following: experimental measurements of different X-ray spectra, half-value layers, percentage depth dose and beam profiles. Monte Carlo modelling of the XSTRAHL 150 unit was performed with the BEAMnrc code. The validity of the model was checked by comparing the theoretical calculations with experimental measurements.ResultsThere was good agreement (∼1%) between experimentally measured and simulated X-ray spectra. Results of half-value layers obtained from simulated and measured spectra showed that there was a maximum of 3·6% difference between BEAMnrc and measurements and a minimum of 2·3%. In addition, simulated percentage depth dose and profile curves have been compared against experimental measurements and show good agreement (within 2% for the depth dose curves and 3–5% for beam profile curves, depending on the applicator size).ConclusionThe results of this study provide information about particles’ interaction in different kilovoltage and filter combinations. This information is useful for X-ray tube design and development of new target/filter combinations to improve beam quality in superficial X-ray radiotherapy. The data presented here may provide a base for comparison and a reference for other or potential new users of the XSTRAHL 150 X-ray unit.

SU-G-TeP1-10: Predicting Photon Percentage Depth Dose From Profile Due to Changes in Beam Quality

2016 ◽  
Vol 43 (6Part26) ◽  
pp. 3654-3654
Author(s):  
S Lebron ◽  
D Kahler ◽  
C Liu
Keyword(s):  
Beam Quality ◽  
Percentage Depth Dose ◽  
Depth Dose

PERCENTAGE DEPTH DOSE FOR HIGH ENERGY X-RAY BEAMS IN RADIOTHERAPY

1973 ◽  
Vol 118 (4) ◽  
pp. 919-922 ◽  
Author(s):  
J. A. RAWLINSON ◽  
H. E. JOHNS
Keyword(s):  
High Energy ◽  
X Ray ◽  
Percentage Depth Dose ◽  
Depth Dose

scholarly journals Dosimetric Characterizations of Megavoltage Therapeutic Photon Beam

2020 ◽  
pp. 83-88
Author(s):  
Md. Abdullah Al Mashud ◽  
M. Jahangir Alam
Keyword(s):  
Photon Beam ◽  
Treatment System ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Dose Variation

This paper presents the dosimetric parameters characterizations of a megavoltage therapeutic photon beam. The main focus of this study is to investigate and analyze the parameters of percentage depth dose (PDD) and tissue maximum ratio (TMR) due to the importance of treatment system. The depth dose characteristics of 6MV photon beam for different field sizes in water phantom has been measured, analyzed and found a robustness results. The results revealed that the depth dose variation from 0.067% to 1.812% and the TMR values varies from 0.501% to 2.111%. It seems the measured dosimetric quantities are clinically relevant for different field sizes and depths.

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