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.

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.

scholarly journals Dosimetric Characterization of Small Radiotherapy Electron Beams Collimated by Circular Applicators with the New Microsilicon Detector

2022 ◽  
Vol 12 (2) ◽  
pp. 600
Author(s):  
Serenella Russo ◽  
Silvia Bettarini ◽  
Barbara Grilli Leonulli ◽  
Marco Esposito ◽  
Paolo Alpi ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Electron Beams ◽  
High Energy ◽  
Field Size ◽  
The Novel ◽  
Linear Accelerators ◽  
Depth Dose ◽  
Dosimetric Data ◽  
Output Factors ◽  
Dose Measurements

High-energy small electron beams, generated by linear accelerators, are used for radiotherapy of localized superficial tumours. The aim of the present study is to assess the dosimetric performance under small radiation therapy electron beams of the novel PTW microSilicon detector compared to other available dosimeters. Relative dose measurements of circular fields with 20, 30, 40, and 50 mm aperture diameters were performed for electron beams generated by an Elekta Synergy linac, with energy between 4 and 12 MeV. Percentage depth dose, transverse profiles, and output factors, normalized to the 10 × 10 cm2 reference field, were measured. All dosimetric data were collected in a PTW MP3 motorized water phantom, at SSD of 100 cm, by using the novel PTW microSilicon detector. The PTW diode E and the PTW microDiamond were also used in all beam apertures for benchmarking. Data for the biggest field size were also measured by the PTW Advanced Markus ionization chamber. Measurements performed by the microSilicon are in good agreement with the reference values for all the tubular applicators and beam energies within the stated uncertainties. This confirms the reliability of the microSilicon detector for relative dosimetry of small radiation therapy electron beams collimated by circular applicators.

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.

Surface dose measurements in chest wall postmastectomy radiotherapy to achieve optimal dose delivery with 6 MV photon beam

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Challapalli Srinivas ◽  
Dilson Lobo ◽  
Sourjya Banerjee ◽  
MS Athiyamaan ◽  
Shreyas Reddy ◽  
...  
Keyword(s):  
Chest Wall ◽  
Optimal Dose ◽  
Photon Beam ◽  
Surface Dose ◽  
Dose Delivery ◽  
Postmastectomy Radiotherapy ◽  
Dose Measurements

Evaluation of thermoplastic Klarity mask use during intensity-modulated radiation therapy for head and neck carcinoma

2018 ◽  
Vol 17 (2) ◽  
pp. 171-178 ◽  
Author(s):  
Khaldoon Radaideh
Keyword(s):  
Radiation Therapy ◽  
Head And Neck ◽  
Intensity Modulated Radiation Therapy ◽  
Planning System ◽  
Skin Dose ◽  
Surface Dose ◽  
Thermoluminescent Dosimeters ◽  
Intensity Modulated ◽  
Skin Doses ◽  
Dose Measurements

AbstractAimTo evaluate the Klarity® Mask with respect to skin doses and toxicity secondary to head and neck cancer radiation treatment.Materials and methodsThis prospective study included five nasopharyngeal cancer patients who underwent intensity-modulated radiation therapy and monitored for skin toxicity. An anatomical Perspex head and neck phantom was designed and used. All patients’ treatment plans were separately transferred to the phantom. Dosimetric measurements were performed using chip-shaped thermoluminescent dosimeters (LiF:Mg,Ti TLDs) which were distributed at certain target points on the phantom. Phantom was irradiated twicely with and without a Klarity® Mask. Three fractions for each patient plan were obtained and compared with treatment planning system (TPS) doses as guided by computed tomography.ResultsThe Klarity mask used for patient immobilisation increased the surface dose by 10·83% more than that without the mask. The average variations between skin dose measurements with and without the Klarity mask for all patients’ plans ranged from 10·26 to 11·83%. TPS overestimated the surface dose by 19·13% when compared with thermoluminescent dosimeters that measured the direct skin dose.ConclusionsKlarity immobilisation mask increases skin doses, as a consequence, surface dose measurements should be monitored and must be taken into account.

scholarly journals Electron Beam Measurements Employing Electron Montecarlo Algorithm on TrueBeam STx® and Clinac iX® Linear Accelerators

2021 ◽  
Vol 9 (B) ◽  
pp. 1730-1738
Author(s):  
Kamal Saidi ◽  
Othmane Kaanouch ◽  
Hanae El Gouach ◽  
Mohamed Reda Mesradi ◽  
Mounir Mkimel ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Beams ◽  
Measured Data ◽  
Field Size ◽  
Large Field ◽  
Linear Accelerators ◽  
Tolerance Intervals ◽  
Depth Dose ◽  
Large Water ◽  
Good Agreement

Electron beam measurement comparison between TrueBeam STx® and Clinac iX® established. Data evaluation of eMC-calculated and measured for TrueBeam STx® performed. Dosimetric parameters measured including depth dose curves for each applicator, percentage depth dose (PDDs) curves without applicator, the profile in-air for a large field size 40×40 cm2, and the Absolute Dose (cGy/MU) for each applicator using a large water phantom (PTW, Freiburg, Germany), employing Roos and Markus plane-parallel ionization chambers. The data were examined for five electron beams of Varian’s TrueBeam STx® and Clinac iX® machines. A comparison between measurement PDDs and calculated by the Eclipse electron Monte Carlo (eMC) algorithm was performed to validate Truebeam STx® commissioning. The measured data indicated that electron beam PDDs from the TrueBeam STx® machine are well matched to those from Clinac iX® machine. The quality index R50 for applicator 15×15 cm2 was in the tolerance intervals. However, Surface dose (Ds) increases with increasing energy for both accelerators. Comparisons between the measured and eMC-calculated values revealed that the R100, R90, R80, and R50 values mostly agree within 5 mm. Measured and calculated bremsstrahlung tail Rp correlates well statistically. Ds agrees mostly within 2%. Electron beams were successfully validated for TrueBeam STx®, a good agreement between modeled and measured data was observed.

scholarly journals Grid Monte Carlo Simulation of a Medical Linear Accelerator

2018 ◽  
Vol 3 (12) ◽  
pp. 40-43 ◽  
Author(s):  
Didi Samir ◽  
Mustapha Zerfaoui ◽  
Abdelilah Moussa ◽  
Yassine Benkhouya ◽  
Mehdi El Ouartiti
Keyword(s):  
Monte Carlo ◽  
Linear Accelerator ◽  
Field Size ◽  
Dose Profile ◽  
Depth Dose ◽  
Grid Simulation ◽  
Medical Linear Accelerator ◽  
Measured Dose ◽  
Better Than ◽  
Good Agreement

A full grid simulation of the head of an Elekta Synergy Platform medical linear accelerator is performed using the Geant4 Monte Carlo platform. The simulation includes all components of the accelerator head and a homogeneous water phantom. Results in terms of depth doses and lateral dose profiles are presented for 6 MV photon beam with the 10x10 cm2 reference field size at 100 cm distance from the source. Overall, a good agreement with the measured dose data is achieved with a precision better than 0.93% and 2.63% for the depth dose profile and lateral dose profiles respectively.

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 Review of surface dose detectors in radiotherapy

2003 ◽  
Vol 3 (2) ◽  
pp. 69-76 ◽  
Author(s):  
E. O'Shea ◽  
P. McCavana
Keyword(s):  
Absorbed Dose ◽  
High Energy ◽  
Skin Dose ◽  
Surface Dose ◽  
Radiographic Film ◽  
Equilibrium Conditions ◽  
Diamond Detector ◽  
Thermoluminescent Dosimeters ◽  
Absorbed Radiation Dose ◽  
Dose Measurements

Several instruments have been used to measure absorbed radiation dose under non-electronic equilibrium conditions, such as in the build-up region or near the interface between two different media, including the surface. Many of these detectors are discussed in this paper. A common method of measuring the absorbed dose distribution and electron contamination in the build-up region of high-energy beams for radiation therapy is by means of parallel-plate ionisation chambers. Thermoluminescent dosimeters (TLDs), diodes and radiographic film have also been used to obtain surface dose measurements. The diamond detector was used recently by the author in an investigation on the effects of beam-modifying devices on skin dose and it is also described in this report.

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