Dosimetric comparison of photon beam profile characteristics for different treatment parameters

2017 ◽  
Vol 16 (4) ◽  
pp. 444-450 ◽  
Author(s):  
Qurat-ul-ain Shamsi ◽  
Maria Atiq ◽  
Atia Atiq ◽  
Saeed Ahmad Buzdar ◽  
Khalid Iqbal ◽  
...  
Keyword(s):  
Linear Accelerator ◽  
Radiation Treatment ◽  
Beam Profile ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Linear Accelerators ◽  
Water Phantom ◽  
Treatment Plans ◽  
Profile Characteristics

AbstractPurposeTo deliver radiation doses with higher accuracy, radiation treatment through megavoltage photon beams from linear accelerators, is accepted widely for treating malignancies. Before calibrating the linear accelerators, it is essential to make a complete analysis of all photon beam profile parameters. The main objective of this exploration was to investigate the 6 and 15 MV photon beam profile characteristics to improve the accuracy of radiation treatment plans.MethodsIn this exploration, treatment parameters like depth, field size and beam energy were varied to observe their effect on dosimetric characteristics of beam profiles in a water phantom, generated by linear accelerator Varian Clinac.ResultsThe results revealed thatDmaxandDmindecreased with increasing depth but increased with increasing field sizes. Both left and right penumbras increased with increasing depth, field size and energy. Homogeneity increased with field size but decreased with depth. Symmetry had no dependence on depth, energy and field size.ConclusionAll the characteristics of photon beam dosimetry were analysed and the characteristics like homogeneity and symmetry measured by an ion chamber in a water phantom came within clinically acceptable level of 3 and 103%, respectively, thus fulfilled the requirements of standard linear accelerator specifications. This exploration can be extended to the determination of beam profile characteristics of electron and photon beams of other energies at various depths and field sizes for designing optimum treatment plans.

Wedge angle confirmation in computer controlled wedge field

2020 ◽  
Vol 7 (3) ◽  
pp. 81-86
Author(s):  
Salman Farrukh
Keyword(s):  
Linear Accelerator ◽  
Beam Energy ◽  
Wedge Angle ◽  
Target Volume ◽  
Field Size ◽  
Published Data ◽  
Linear Accelerators ◽  
Water Phantom ◽  
Ion Chamber ◽  
Computer Controlled

Aim: The use of computer controlled wedge system is an important segment of radiotherapy and increases the uniformity of dose in the target volume. The aim of this study is to verify the virtual wedge angles from the machine setup angles in Siemens ONCOR Linear accelerator (Linac) and compare with published data of different linear accelerators as a function of beam energy and field sizes. Method and material: This experiment was carried out on Siemens ONCOR impression linear accelerator (Linac). The doses at different depth were measured by using CC13 ion chamber. During our work the source to surface distance was kept 100 cm. The square field sizes on which we worked were 10 cm2, 15cm2 and 20 cm2.The selected Virtual wedge angles for our study are 15°, 30°, 45° and 60°.This work is carried out for both photon energies 15 MV and 6 MV, tissue equivalent water phantom IBA blue water phantom inside which all the observations were taken. The LDA 99 detector for virtual wedge profile was used. The wedge angle were calculated for the Siemen’s given formula. The variation in wedge angle from machine setup angle and published data as a function of beam energy and field sizes were analyzed. Results: The variation increases with field size and wedge angle but decreases with beam energy. Conclusion: Deviations are under 3% which are acceptable before treatment planning.

scholarly journals COLLIMATOR EXCHANGE EFFECT OF MEGAVOLTAGE PHOTON BEAMS AND ITS IMPACT ON CLINICAL DOSIMETRY

2020 ◽  
pp. 1-4
Author(s):  
Shachindra Goswami ◽  
Bhaveshwar Yadav ◽  
Shashi Bhushan Sharma ◽  
Mithu Barthakur ◽  
Pranjal Goswami ◽  
...  
Keyword(s):  
Linear Accelerator ◽  
High Energy ◽  
Field Size ◽  
Data Sets ◽  
Photon Beams ◽  
Linear Accelerators ◽  
Exchange Effect ◽  
Maximum Percentage ◽  
Percentage Difference ◽  
Collimator Scatter Factor

AIM To determine the Collimator Exchange Effect (CEE) for telecobalt unit (Bhabhatron -II TAW) and Linear accelerator unit (Varian Trilogy). MATERIALS AND METHOD The study was carried out in Bhabhatron-II TAW Telecobalt machine and Varian Trilogy Linear Accelerator. The study was done to find the collimator scatter factor (S¬c) for rectangular fields at 5 and 10gm/cm2 depths using indigenously designed mini phantom. Three sets of electrometer reading were noted for the irradiation of each field size and the average was taken for calculation. Sc values for different rectangular fields were then calculated from these data sets and the CEE at two depths (5 and 10 gm/cm2) for the 6MV and 15MV photon and Co-60 gamma beam were calculated. RESULTS The values of Sc obtained for the rectangular fields as alternatively defined by X & Y jaws are different for high energy photon beams indicating CEE. The maximum percentage difference between the Sc of the corresponding collimator settings for the Bhabhatron-II TAW unit for depths 5 and 10gm/cm2 were found to be 0.42% and 0.5% respectively. Sc values for 6MV and 15MV photon beams were found to be higher when Y-jaw (upper jaw) acts as the longer side of the rectangular field. The maximum percentage difference between the Sc values of the corresponding collimator settings for 6MV at depths 5 and 10gm/cm2 were 2.74% and 2.87% respectively whereas for 15 MV the differences were 3% and 2.99%. CONCLUSION The CEE of Cobalt Teletherapy units can be ignored in clinical dosimetry. However, the CEE of Linear Accelerators having energies 6MV & 15MV should be taken into consideration. A two dimensional table of Sc should be generated for rectangular fields during MU calculations in Linear Accelerators. For TPS based calculations, the generated data should be incorporated during beam modeling for accurate dose delivery in clinical dosimetry.

scholarly journals Surface Dose for Five Telecobalt Machines, 6MV Photon Beam from Four Linear Accelerators and a Hi-Art TomoTherapy

2008 ◽  
Vol 7 (5) ◽  
pp. 381-384 ◽  
Author(s):  
Rajesh A. Kinhikar
Keyword(s):  
Linear Accelerator ◽  
Photon Beam ◽  
Field Size ◽  
Surface Dose ◽  
Linear Accelerators ◽  
Thermoluminescent Dosimeters ◽  
Medical Technologies ◽  
Dose Measurements ◽  
Good Agreement

The purpose of this study was to estimate the surface dose for five telecobalt machines (four from Best Theratronics Limited, Canada, one from Panacea Medical Technologies, India), 6 MV photon beam (static) from four linear accelerators (three Varian linear accelerators and one Siemens) and Hi-Art Tomotherapy unit. The surface dose was measured with Thermoluminescent dosimeters in phantom slabs. For Tomotherapy 6 MV beam the surface dose was estimated as 32% while it was 35%, 33%, and 36% for Clinac 6EX, Clinac 2100CD, and Clinac 2100C linear accelerators, respectively. Similarly, the surface dose for 6 MV photon beam from Primus linear accelerator was estimated as 35%. Surface doses from telecobalt machines Equinox-80, Elite-80, Th-780C, Th-780, and Bhabhatron-II was found to be 30%, 29.1%, 27.8%, 29.3%, and 29.9% for 10 cm × 10 field size, respectively. Measured surface dose from all four linear accelerators were in good agreement with that of the Tomotherapy. The surface dose measurements were useful for Tomotherapy to predict the superficial dose during helical IMRT treatments.

scholarly journals Dosimetric characterization of medical linear accelerator Photon and Electron beams for the treatment accuracy of cancer patients

2021 ◽  
Vol 3 (1) ◽  
pp. 041-059
Author(s):  
Motiur Rahman ◽  
M Shamsuzzaman ◽  
Manoshi Sarker ◽  
Abdul Jobber ◽  
Mohsin Mia ◽  
...  
Keyword(s):  
Linear Accelerator ◽  
Planning Process ◽  
Electron Beams ◽  
Small Deviation ◽  
Beam Profile ◽  
Field Size ◽  
Photon Beams ◽  
Depth Dose ◽  
Medical Linear Accelerator

In radiotherapy treatment planning process, quality assessment (QA) is indispensable for achieving accuracy and avoidance of treatment errors. In this perspective, present study focused on the Photon and Electron beams characterization of a medical linear accelerator (LINAC) to ascertain dosimetric QA in Absolute and Reference dosimetry. In this connection, the beam outputs were investigated in terms of Dmax and Dw,max (dose at depth dmax) in absolute dosimetry for Photon and Electron beams, respectively. In accordance with the measured Dmax and Dw,max parameters, Photon and Electron beam outputs were standardized to ensure standard output of 1 cGy/MU. In reference dosimetry, the parametric evaluation was performed for dosimetric QA in terms of percent depth dose (PDD), beam profile flatness and symmetry, output factors: Scp, Sc, Sp with varying field size (FS) ranging from 4´4 cm2 to 40´40 cm2 normalized at FS 10´10 cm2 for the 6 MV and 10 MV Photon beams. The measured PDDs at 10 cm depth (D10) were found to be 66.8% and 73.6% for 6 MV and 10 MV Photon beams, respectively, with significantly small deviation of 1% and 0.8% in comparison with an international PDD protocol of British Journal of Radiology-25 (BJR -25). In the case of Electron beams characterization, PDD was verified with 10´10 cm2 cone/applicator, beam profile flatness and symmetry were analyzed at the field sizes ranging from 6´6 cm2 to 25´25 cm2 normalized at 10´10 cm2 cone/applicator, and Electron cone ratios were investigated for a given cone/applicator relative to the 15´15 cm2 one for the 6, 9, 12, 15 MeV Electron energies. The PDDs of all the Electron beams revealed reasonable consistency with manufacturer’s estimations of 90%, 80%, and 50% PDDs at various depths of ionization.

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 Improving Clinical dosimetric Accuracy of cancer treatment using a special quality of Electron and Photon Beam

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Ayesha Ikhlaq ◽  
Saeed Ahmad Buzdar ◽  
Muhammad Usman Mustafa ◽  
Sana Salahuddin ◽  
Mehr-Un-Nisa ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Electron Beam ◽  
Electron Beams ◽  
Photon Beam ◽  
Field Size ◽  
External Beam Radiation ◽  
Photon Beams ◽  
Depth Dose ◽  
Electron And Photon

In external beam radiation therapy, electron and photon beams have extraordinary characteristics in the treatment of cancer. The electron and photon beam characteristic are essential to study before calibration of machine. This study focused on the dosimetric characteristics of different energies of electron beams for different field size. The basic objective of this work is, to calculate dosimetric parameters and characteristics of electron beam, specially depth dose characteristics along central axis. In this work, 6 MeV, 9 MeV, 12 MeV, 15 MeV and 18 MeV of electron beam and 6 MV and 15 MV of photon beam with different field size is used. Characteristics of depth dose of electron and photon beam in water have analyzed to provide better quality of radiation therapy treatment planning. The different beam characteristics are due to different interactions that occurs between electron beams giving them a definite range whereas photon beams are attenuated leading to dose deposition and much larger range with no definite end. Depth dose characteristics of electron and photon beams do not show same characteristics as interaction of beam with matter depends on the quality of beam. Attenuation and penetration factors change with changing dosimetric parameters. Complete analysis of dosimetric characteristics of electron and photon beam help to choose more accurate beam for the treatment of cancer. This work will help to increase accuracy in treatment of cancer with radiotherapy.

scholarly journals Factor 10 Expedience of Monthly Linac Quality Assurance via an Ion Chamber Array and Automation Scripts

2019 ◽  
Vol 18 ◽  
pp. 153303381987689
Author(s):  
Lawrie B. Skinner ◽  
Yong Yang ◽  
Annie Hsu ◽  
Lei Xing ◽  
Amy S. Yu ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Standard Deviation ◽  
Linear Accelerator ◽  
Data File ◽  
Field Size ◽  
Linear Accelerators ◽  
Ion Chamber ◽  
Medical Linear Accelerators ◽  
Jaw Position ◽  
Dosimetric Leaf Gap

Purpose: While critical for safe and accurate radiotherapy, monthly quality assurance of medical linear accelerators is time-consuming and takes physics resources away from other valuable tasks. The previous methods at our institution required 5 hours to perform the mechanical and dosimetric monthly linear accelerator quality assurance tests. An improved workflow was developed to perform these tests with higher accuracy, with fewer error pathways, in significantly less time. Methods: A commercial ion chamber array (IC profiler, Sun Nuclear, Melbourne, Florida) is combined with automation scripts to consolidate monthly linear accelerator QA. The array was used to measure output, flatness, symmetry, jaw positions, gated dose constancy, energy constancy, collimator walkout, crosshair centering, and dosimetric leaf gap constancy. Treatment plans were combined with automation scripts that interface with Sun Nuclear’s graphical user interface. This workflow was implemented on a standard Varian clinac, with no special adaptations, and can be easily applied to other C-arm linear accelerators. Results: These methods enable, in 30 minutes, measurement and analysis of 20 of the 26 dosimetric and mechanical monthly tests recommended by TG-142. This method also reduces uncertainties in the measured beam profile constancy, beam energy constancy, field size, and jaw position tests, compared to our previous methods. One drawback is the increased uncertainty associated with output constancy. Output differences between IC profiler and farmer chamber in plastic water measurements over a 6-month period, across 4 machines, were found to have a 0.3% standard deviation for photons and a 0.5% standard deviation for electrons, which is sufficient for verifying output accuracy according to TG-142 guidelines. To minimize error pathways, automation scripts which apply the required settings, as well as check the exported data file integrity were employed. Conclusions: The equipment, procedure, and scripts used here reduce the time burden of routine quality assurance tests and in most instances improve precision over our previous methods.

Study of unflattened photon beams shaped by multileaf collimator using BEAMnrc code

2016 ◽  
Vol 15 (4) ◽  
pp. 392-401
Author(s):  
Ankit kajaria ◽  
Neeraj Sharma ◽  
Shiru Sharma ◽  
Satyajit Pradhan ◽  
Abhijit Mandal ◽  
...  
Keyword(s):  
Beam Line ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Multileaf Collimators ◽  
Depth Dose ◽  
Beamnrc Code ◽  
Flattening Filter Free ◽  
Flattening Filter ◽  
Beam Delivery

AbstractPurposeIn our study basic dosimetric properties of a flattening filter free 6 MV photon beam shaped by multileaf collimators (MLC) is examined using the Monte Carlo (MC) method.Methods and MaterialsBEAMnrc code was used to make a MC simulation model for 6 MV photon beam based on Varian Clinic 600 unique performance linac, operated with and without a flattening filter in beam line. Dosimetric features including central axis depth dose, beam profiles, photon and electron spectra were calculated and compared for flattened and unflattened cases.ResultsDosimetric field size and penumbra were found to be smaller for unflattened beam, and the decrease in field size was less for MLC shaped in comparison with jaw-shaped unflattened beam. Increase in dose rate of >2·4 times was observed for unflattened beam indicating a shorter beam delivery time for treatment. MLC leakage was found to decrease significantly when the flattening filter was removed from the beam line. The total scatter factor showed slower deviation with field sizes for unflattened beam indicating a reduced head scatter.ConclusionsOur study demonstrated that improved accelerator characteristics can be achieved by removing flattening filter from beam line.

Reconstruction of Bremsstrahlung Spectrum of Medical Electron Linear Accelerators from Deep Dose Distributions in Water Phantom

2017 ◽  
Vol 62 (5) ◽  
pp. 47-51
Author(s):  
В. Климанов ◽  
V. Klimanov ◽  
Ж. Галяутдинова ◽  
Zh. Galyautdinova ◽  
Н. Могиленец ◽  
...  
Keyword(s):  
Dose Distribution ◽  
Average Energy ◽  
Field Size ◽  
Bremsstrahlung Spectrum ◽  
Reconstruction Method ◽  
Electron Linear Accelerator ◽  
Linear Accelerators ◽  
Dose Distributions ◽  
Water Phantom ◽  
Dose Kernels

Purpose: Development of the bremsstrahlung spectrum reconstruction method of medical electron linear accelerators (ELA) with different field sizes on the base of the deep dose distributions in a water phantom and determination of photon spectra for Varian Trilogy accelerator 6 MV. Material and methods: The proposed methodology is based on the use of dose kernels algorithm of point monoenergetic monodirectional source (pencil beam (PB)) for the deep dose distribution calculation, created different cross-section beams of in a water phantom, and experimental measurements of these distributions. For solving the inverse problem is applied Toolbox routines 'ptimtool knowing mathematical package MATLAB to solve. Results: Bremsstrahlung energy spectrum generated medical accelerator Varian Triology with different sizes of square fields from 3×3 up to 40×40 cm and average energy photons, depending on the size of the fields were received. Dose kernels for a set of defined energies PB were calculated. Depth dose distribution in a water phantom, calculated using the obtained spectra and dose kernels agree well with measurement dose distributions. Conclusion: The proposed technique reconstruction of bremsstrahlung spectrum of electron linear accelerator is adequate. Average energy spectra of bremsstrahlung photons for Varian Trilogy Accelerator in regime 6 MV varies from 1.71 to 1.43 MeV depending on the field size.

scholarly journals Studies of Dosimetry Protocols for Accelerated Photons and Electrons Delivered from Medical Linear Accelerator

2021 ◽  
Keyword(s):  
Comparative Study ◽  
Linear Accelerator ◽  
Electron Beams ◽  
Absorbed Dose ◽  
Photon Beam ◽  
Photon Beams ◽  
Medical Linear Accelerator ◽  
The Comparative Study ◽  
Electron And Photon ◽  
Medical Linac

We focus on the comparative study of dosimetry protocols in radiotherapy for accelerated photon and electron delivered from medical linear accelerator (LINAC). In this study, a comparison between the protocols (TRS 398, DIN 6800-2 and TG 51) for both the electron and photon delivered from Clinac 2300CD and Clinac DHX 3186 were performed. We used photon beams with energies of 6 and 15 MV and electron beams of 4, 6, 9, 12, 15 and 18 MeV for both Medical Linac. In case of Clinac the maximum deviations for the relative dose at Dmax for the photon beam (15 MV) among the protocols was observed to be 1.18% between TRS-398 and TG-51, 1.56% between TG-51 and DIN 6800-2; and 0.41% between TRS-398 and DIN 6800-2. Conversely, these deviations were 3.67% between TRS-398 and TG-51, 3.92% between TG-51 and DIN 6800-2 for 4 MeV and 0.95% between TRS-398 and DIN 6800-2 in the case of Clinac 2300 CD for the PTW Markus and Exradin A10. For the measurement of the maximum absorbed dose depth to water using three protocols, the maximum deviations were observed between TRS 398 and TG-51 as well as TG51 and DIN 6800-2.

Sign in / Sign up

Export Citation Format

Share Document