scholarly journals Feasibility studies of using thin entrance window photodiodes for clinical electron beam dosimetry

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Cristina R. Nascimento ◽  
Viviane K. Asfora ◽  
Vinicius R. M. Barros ◽  
Josemary A. C. Gonçalves ◽  
Luiza F. R. Andrade ◽  
...  
Keyword(s):  
Electron Beam ◽  
Ionization Chamber ◽  
Electron Beams ◽  
Beam Quality ◽  
Absorbed Dose ◽  
Feasibility Studies ◽  
Entrance Window ◽  
Sensitive Volume ◽  
Depth Dose ◽  
Beam Dosimetry

The response of the commercial XRA-24 PIN photodiode (5.76 mm2 active area) for clinical electron beam dosimetry covering the range of 8-12 MeV was investigated. Within this energy range, the charge generated in the diode’s sensitive volume is linearly dependent on the absorbed dose up to 320 cGy.  However, charge sensitivity coefficients evidenced that the dose response of the diode is slightly dependent on the electron beam energy. Indeed, the diode’s energy dependence was within 8.5% for 8-12MeV electron beams. On the other hand, it was also observed an excellent repeatability of these results with a variation coefficient (VC) lower than 0.4%, which is within the 1% tolerance limit recommended by the AAPM TG-62. Furthermore, the agreement between the percentage depth dose profiles (PDD) gathered with the diode and the ionization chamber allowed achieving the electron beam quality within 1% of that obtained with the ionization chamber. Based on these results, the photodiode XRA-24 can be a reliable and inexpensive alternative for electron beams dosimetry.

scholarly journals Evaluation of some dosimetric properties of a dedicated plane parallel ionization chamber for radiotherapy electron beams

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Jonas Oliveira da Silva ◽  
Fernanda Beatrice Conceição Nonato ◽  
Francisco Glaildo Almeida Sampaio ◽  
Linda V. Ehlin Caldas
Keyword(s):  
Electron Beam ◽  
Ionization Chamber ◽  
Electron Beams ◽  
International Standards ◽  
Field Size ◽  
Guard Ring ◽  
Sensitive Volume ◽  
Plane Parallel ◽  
Nail Polish ◽  
Beam Dosimetry

Ionization chambers are the reference detectors for electron beam dosimetry. In this paper a dedicated radiotherapy plane parallel ionization chamber manufactured with low cost materials is presented for dosimetry in electron beams. The ionization chamber tested has a sensitive volume of 0.4 cm³, and the collecting electrode and the guard ring were painted with a homogeneous mixture of nail polish and graphite. The dedicated ionization chamber presented linearity of the response with the absorbed dose in the range of 0.5 Gy to 8.0 Gy, an increase of the response with the field size increasing, an angular dependence within ±5°, as recommended by international standards, and a polarity effect of 0.78% with the field size. From the results obtained, it is possible to conclude that the plane parallel ionization chamber tested in this work presents potential use for electron beam dosimetry in clinical routine.

scholarly journals Commissioning Measurements of Electron Beam Using Montecarlo Algorithm on Truebeam STx® and Compariaon with Clinac iX Linear Accelerator

2021 ◽  
Vol 229 ◽  
pp. 01041
Author(s):  
Kamal Saidi ◽  
Redouane El Baydaoui ◽  
Hanae El Gouach ◽  
Othmane Kaanouch ◽  
Mohamed Reda Mesradi
Keyword(s):  
Electron Beam ◽  
Electron Beams ◽  
Measured Data ◽  
University Hospital ◽  
Field Size ◽  
Large Field ◽  
Water Phantom ◽  
Depth Dose ◽  
International University ◽  
The Absolute

TrueBeam STx latest generation linear accelerators (linacs) installed at Sheikh Khalifa International University Hospital in Casablanca, Morocco. The aim of this is to present and compare the result of the Electron commissioning measurement on TrueBeam Stx and clinac iX installed at Sheikh Khalifa International University Hospital in Casablanca, Morocco. A compariaon of eMC calculations and measurements for TrueBeam Stx were evaluated. Dosimetric parameters are systematically measured using a large water phantom 3D scanning system MP3 Water Phantom (PTW, Freiburg, Germany). The data of the electron beams commissioning including depth dose curves for each applicator, depth dose curves without applicator and the profile in air for a large field size 40x 40cm2, and the Absolute Dose (cGy/MU) for each applicator. All the data were examined and compared for five electron beams (E6MeV, E9MeV, E12MeV, E16MeV and E20MeV) of Varian’s TrueBeam STx and Clinac iX machines. A comparison, between measurement PDDs and calculated by the Eclipse electron Monte Carlo (eMC) algorithm were performed to validate Truebeam Stx commissioning. All this measurements were performed with a Roos and Markus plane parallel chamber. Our measured data indicated that electron beam PDDs from the TrueBeam Stx machine are well matched to those from our Varian Clinac iX machine. Significant differences between TrueBeam and Clinac iX were found in in‐air profiles and open field output. Maximum depth dose for the TrueBeam Stx and Clinac iX for the following energies (6, 9, 12, 16, 20 MeV) are respectively (1.15; 1.89; 2.6; 3.1; and 2.35) and (1.24; 1.95; 2.70; 2.99 and 2.4cm). For the TrueBeam Stx and Clinac iX the quality index R50 for applicator 15x15 cm2 are in the tolerance intervals. Surface dose increases by increasing energy for both machines. The Absolute Dose (cGy/MU) calibrated for both machine in Dmax at 1cGy/MU for the reference field size cone 15x15 cm2. Bremsstrahlung tail Rp per energy levels as follows for the TrueBeam Stx : 6 MeV – 2.85 cm, 9 MeV – 4.28 cm, 12 MeV – 5.97 cm, 16 MeV – 7.88 cm and 20 MeV – 9.86 cm. and for the Clinac iX : 6 MeV – 2.86 cm, 9 MeV – 4.32 cm, 12 MeV – 5.96 cm, 16 MeV – 7.93 cm and 20 MeV – 10.08 cm. A good agreement between modeled and measured data is observed.

High dose-per-pulse electron beam dosimetry - A model to correct for the ion recombination in the Advanced Markus ionization chamber

2017 ◽  
Vol 44 (3) ◽  
pp. 1157-1167 ◽  
Author(s):  
Kristoffer Petersson ◽  
Maud Jaccard ◽  
Jean-François Germond ◽  
Thierry Buchillier ◽  
François Bochud ◽  
...  
Keyword(s):  
Electron Beam ◽  
Ionization Chamber ◽  
Pulse Electron Beam ◽  
High Dose ◽  
Pulse Electron ◽  
Ion Recombination ◽  
Beam Dosimetry

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.

Estimating the absolute flux distribution for a synchrotron X-ray beam using ionization-chamber measurements with various filters

2017 ◽  
Vol 24 (5) ◽  
pp. 939-953 ◽  
Author(s):  
Andrew W. Stevenson ◽  
Francesca Di Lillo
Keyword(s):  
Ionization Chamber ◽  
Flux Distribution ◽  
Beam Quality ◽  
Absorbed Dose ◽  
Absorbed Dose Rate ◽  
X Ray ◽  
Absolute Flux ◽  
The Absolute ◽  
Using Data ◽  
Chamber Measurements

It is shown that an extensive set of accurate ionization-chamber measurements with a primary polychromatic synchrotron X-ray beam transmitted through various filter combinations/thicknesses can be used to quite effectively estimate the absolute flux distribution. The basic technique is simple but the `inversion' of the raw data to extract the flux distribution is a fundamentally ill-posed problem. It is demonstrated, using data collected at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron, that the absolute flux can be quickly and reliably estimated if a suitable choice of filters is made. Results are presented as a function of the magnetic field (from 1.40 to 4.00 T) of the superconducting multi-pole wiggler insertion device installed at IMBL. A non-linear least-squares refinement of the data is used to estimate the incident flux distribution and then comparison is made with calculations from the programsSPECTRA,XOPandspec.exe. The technique described is important not only in estimating flux itself but also for a variety of other, derived, X-ray properties such as beam quality, power density and absorbed-dose rate. The applicability of the technique with a monochromatic X-ray beam for which there is significant harmonic contamination is also demonstrated. Whilst absolute results can also be derived in this monochromatic beam case, relative (integrated) flux values are sufficient for our primary aim of establishing reliable determinations of the percentages of the various harmonic components.

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 Calibration of Therapy Level Ionization Chamber at 60Co Teletherapy Beam Used for Radiation Therapy

2018 ◽  
Vol 79 ◽  
pp. 1-8
Author(s):  
Md. Ali Reza ◽  
Md. Rakibul Islam ◽  
Md. Shakilur Rahman ◽  
Md. Shamsuzzaman ◽  
Md. Rashedur Rahman ◽  
...  
Keyword(s):  
Ionization Chamber ◽  
Absorbed Dose ◽  
Critical Issue ◽  
Calibration Factor ◽  
Ionization Chambers ◽  
Depth Dose ◽  
Output Factors ◽  
Absorbed Dose To Water ◽  
Radiotherapy Dosimetry ◽  
Water Measurement

The accuracy and traceability of absorbed dose to water measurement of radiotherapy beam is a critical issue to achieve the curative outcome of cancer patients. The current dosimetry protocols for radiotherapy beams TRS-398, TG-51 and DIN-6800-2 are based on the calibration factor of ionization chamber in terms of absorbed dose to water for 60Co beam. The accuracy of the calibration factor of ionization chamber as well as output of radiotherapy beam is the primary requirements of precisional dose deliver to the tumor which is the QA part of radiotherapy dosimetry. In the present study, we have calibrated 9 different ionization chambers (8 thimbles and 1 parallel plate) of various active volumes for 60Co beam against reference standard NE2571 and compared with manufacturer’s values. The Percentage Depth Dose (PDD) and Output Factors (OF) of two cobalt units were measured with standard calibration system by following IAEA dosimetry protocol TRS-398 and compare with 6 MV photon beam from medical linear accelerator. The traceability of the dosimetry was verified by the participation of postal dose IAEA/WHO intercomparison program. The aim of the participation was to investigate uncertainties involved in the calibration of Ionization Chamber (IC) and absorbed dose measurement. The percentage of deviation relative to IAEA mean dose was found to be -0.2% (traceable limit ±5%), which shows an excellent agreement of calibration of beam as well as ionization chamber with international standard. The deviation of factors of ionization chambers between the measured and manufacturer’s values were found within 0.07-2.81% with an uncertainty of ±1.5% (k=1).

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