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.

Physical approach to depth dose distributions in a water phantom irradiated by a teleisotope photon beam

1980 ◽  
Vol 7 (2) ◽  
pp. 120-126 ◽  
Author(s):  
Sain D. Ahuja ◽  
Steven L. Stroup ◽  
Marion G. Bolin ◽  
S. Julian Gibbs
Keyword(s):  
Photon Beam ◽  
Dose Distributions ◽  
Water Phantom ◽  
Depth Dose ◽  
Physical Approach

Erratum: Physical approach to depth dose distributions in a water phantom irradiated by a teleisotope photon beam [Med. Phys. 7 , 120 (1980)]

1980 ◽  
Vol 7 (5) ◽  
pp. 550-550
Author(s):  
Sain D. Ahuja ◽  
Steven L. Stroup ◽  
Marion G. Bolin ◽  
S. Julian Gibbs
Keyword(s):  
Photon Beam ◽  
Dose Distributions ◽  
Water Phantom ◽  
Depth Dose ◽  
Physical Approach

Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality

2018 ◽  
Vol 18 (03) ◽  
pp. 280-284 ◽  
Author(s):  
Mohamed Bencheikh ◽  
Abdelmajid Maghnouj ◽  
Jaouad Tajmouati
Keyword(s):  
Exponential Decay ◽  
Target Volume ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Energy Agency ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Beam Dosimetry

AbstractAimThe purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality.Materials and methodsFor the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations.Results and discussionThe 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions.ConclusionThe dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.

scholarly journals Design and Analysis Effect of Gantry Angle Photon Beam 4 MV on Dose Distributions using Monte Carlo Method EGSnrc Code System

2016 ◽  
Vol 27 (1) ◽  
pp. 18-20
Author(s):  
Uum Yuliani ◽  
Ridwan Ramdani ◽  
Freddy Haryanto ◽  
Yudha Satya Perkasa ◽  
Mada Sanjaya
Keyword(s):  
Monte Carlo ◽  
Vertical Axis ◽  
Photon Beam ◽  
Field Size ◽  
Dose Calculations ◽  
Dose Distributions ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Surface Field ◽  
Gantry Angle

Varian linac modeling has been carried out to obtain Percentage Depth Dose (PDD) and profiles using variations gantry angle 0o, 15o, 30o , 45o in the vertical axis of the surface, field size 10x10 cm2, photon beam 4 MV and Monte Carlo simulations. Percentage Depth Dose and profile illustrates dose distributions in a phantom water measuring 40x40x40 cm3, changes gantry is one of the factors that determine the distribution of the dose to the patient research shows changes in Dmax in the Percentage Depth Dose is affected by changes in the angle gantry resulted in the addition of the area build up so it can be used for therapy in the region and produce skin sparing effects that can be used to protect the skin from exposure to radiation. The graph result is profiles obtained show lack simetrisan in areas positive quadrant has a distribution of fewer doses than the quadrant of negative as well as the slope of the surface so that it can be used for some cases treatments that require a depth and a certain slope, dose calculations are more accurate and can minimize side effects.

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.

Lateral scatter correction algorithm for percentage depth dose in a large-field photon beam

1997 ◽  
Vol 22 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Beatriz Sánchez-Nieto ◽  
Francisco Sánchez-Doblado ◽  
JoséAntonio Terrón ◽  
Rafael Arráns ◽  
L. Errazquin
Keyword(s):  
Scatter Correction ◽  
Photon Beam ◽  
Large Field ◽  
Correction Algorithm ◽  
Percentage Depth Dose ◽  
Depth Dose

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.

scholarly journals Dosimetric Algorithm to Reproduce Isodose Curves Obtained from a LINAC

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Julio Cesar Estrada Espinosa ◽  
Segundo Agustín Martínez Ovalle ◽  
Cinthia Kotzian Pereira Benavides
Keyword(s):  
Monte Carlo ◽  
Absorbed Dose ◽  
Numerical Data ◽  
Radiation Beam ◽  
Calculation Time ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Dose Profile ◽  
Depth Dose ◽  
Mcnpx Code

In this work isodose curves are obtained by the use of a new dosimetric algorithm using numerical data from percentage depth dose (PDD) and the maximum absorbed dose profile, calculated by Monte Carlo in a 18 MV LINAC. The software allows reproducing the absorbed dose percentage in the whole irradiated volume quickly and with a good approximation. To validate results an 18 MV LINAC with a whole geometry and a water phantom were constructed. On this construction, the distinct simulations were processed by the MCNPX code and then obtained the PDD and profiles for the whole depths of the radiation beam. The results data were used by the code to produce the dose percentages in any point of the irradiated volume. The absorbed dose for any voxel’s size was also reproduced at any point of the irradiated volume, even when the voxels are considered to be of a pixel’s size. The dosimetric algorithm is able to reproduce the absorbed dose induced by a radiation beam over a water phantom, considering PDD and profiles, whose maximum percent value is in the build-up region. Calculation time for the algorithm is only a few seconds, compared with the days taken when it is carried out by Monte Carlo.

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.

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