Beam generation and planar imaging at energies below 2.40 MeV with carbon and aluminum linear accelerator targets

Parsons, David; Robar, James L.

doi:10.1118/1.4730503

Cited by 20 publications

(34 citation statements)

References 21 publications

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“…For the 2.5 MV/IB, an energy spread of 0.3 MeV was used. As in previous work, 5 the carbon target beams were generated with a 2.35 MeV mono-energetic electron beam. As described by Sawkey et al, 19 the lateral profiles of the spot size were taken to be Gaussians, with sigmas of 0.6866 and 0.7615 mm (6 MV flattened), 0.6645 and 0.7274 mm (6 MV FFF), 0.72 and 0.76 mm (low-Z beams) in the crossplane and inplane directions, respectively.…”

Section: B Monte Carlo Photon Beam Simulationsmentioning

confidence: 99%

“…The target for the 2.35 MV/carbon beamline was a 6.7 mm thick disc of carbon (ρ = 2.00 g/cm 3 ) with a diameter of 5 cm. Target thickness was modified from previous work 5 to account for the change in material density specified according to the values in Geant4. The flattening filter and the brass plate were removed for both the 2.35 MV/carbon and 2.5 MV/IB beams.…”

Section: B Monte Carlo Photon Beam Simulationsmentioning

confidence: 99%

“…The 2.35 MV/carbon model was modified from previous work, 5 to account for changes present in the most recent High Energy Accelerator Monte Carlo Data Package provided by Varian Medical Systems under a non-disclosure agreement. These modifications largely consisted of the inclusion of the metal plating on the dielectric windows of the monitor chamber.…”

Section: B Monte Carlo Photon Beam Simulationsmentioning

confidence: 99%

“…Next, a carbon target operated at 2.35 MeV and a newly proposed 2.50 MeV commercial imaging target beam (Varian Medical Systems, Inc., Palo Alto, CA) were then modeled. The low-Z target beams were compared to a previously validated 5 Monte Carlo simulation of a carbon target operated at 2.35 MeV generated in a Varian 2100EX Clinac using BEAMnrc.…”

Section: Introductionmentioning

confidence: 99%

“…Monte Carlo simulation of low atomic number (Z) targets in conventional linear accelerators (Linacs), such as the Varian Clinac series [1][2][3][4][5][6] (Varian Medical Systems, Inc., Palo Alto, CA), Elekta SL25 and Precise Treatment Systems [7][8][9] (Elekta Oncology Systems, Crawley, UK) or Siemens Primus and Oncor Linacs [10][11][12] (Siemens Medical Solutions, Concord, CA), have all used geometric and material specifications of the Linac provided by the manufacturer to help construct accurate models in BEAMnrc. 13 However, this technical information for Varian's TrueBeam Linac platform (Varian Medical Systems, Inc., Palo Alto, CA) has not been made available to the research community for proprietary reasons.…”

Section: Introductionmentioning

confidence: 99%

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A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinac^a)

2014

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Purpose: The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. Methods: VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code, was used to model the Linac treatment head components. Particles were propagated through the lower portion of the treatment head using BEAMnrc. Dose distributions and spectral distributions were calculated using DOSXYZnrc and BEAMdp, respectively. For validation, 6 MV flattened and flattening filter free (FFF) photon beams were generated and compared to measurement for square fields, 10 and 40 cm wide and at d max for diagonal profiles. Two low-Z targets were investigated: a 2.35 MeV carbon target and the proposed 2.50 MeV commercial imaging target for the TrueBeam platform. A 2.35 MeV carbon target was also simulated in a 2100EX Clinac using BEAMnrc. Contrast simulations were made by scoring the dose in the phosphor layer of an IDU20 aSi detector after propagating through a 4 or 20 cm thick phantom composed of water and ICRP bone. Results: Measured and modeled depth dose curves for 6 MV flattened and FFF beams agree within 1% for 98.3% of points at depths greater than 0.85 cm. Ninety three percent or greater of points analyzed for the diagonal profiles had a gamma value less than one for the criteria of 1.5 mm and 1.5%. The two low-Z target photon spectra produced in TrueBeam are harder than that from the carbon target in the Clinac. Percent dose at depth 10 cm is greater by 3.6% and 8.9%; the fraction of photons in the diagnostic energy range (25-150 keV) is lower by 10% and 28%; and contrasts are lower by factors of 1.1 and 1.4 (4 cm thick phantom) and 1

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Section: B Monte Carlo Photon Beam Simulationsmentioning

confidence: 99%

Section: B Monte Carlo Photon Beam Simulationsmentioning

confidence: 99%

Section: B Monte Carlo Photon Beam Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinac^a)

2014

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Treatment planning with a 2.5 MV photon beam for radiation therapy

Khaledi

Hayes

Belshaw

et al. 2022

J Applied Clin Med Phys

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Purpose The shallow depth of maximum dose and higher dose fall‐off gradient of a 2.5 MV beam along the central axis that is available for imaging on linear accelerators is investigated for treatment of shallow tumors and sparing the organs at risk (OARs) beyond it. In addition, the 2.5 MV beam has an energy bridging the gap between kilo‐voltage (kV) and mega‐voltage (MV) beams for applications of dose enhancement with high atomic number (Z) nanoparticles. Methods We have commissioned and utilized a MATLAB‐based, open‐source treatment planning software (TPS), matRad, for intensity‐modulated radiation therapy (IMRT) dose calculations. Treatment plans for prostate, liver, and head and neck (H&N), nasal cavity, two orbit cases, and glioblastoma multiforme (GBM) were performed and compared to a conventional 6 MV beam. Additional Monte Carlo calculations were also used for benchmarking the central axis dose. Results Both beams had similar planning target volume (PTV) dose coverage for all cases. However, the 2.5 MV beam deposited 6%–19% less integral doses to the nasal cavity, orbit, and GBM cases than 6 MV photons. The mean dose to the heart in the liver plan was 10.5% lower for 2.5 MV beam. The difference between the doses to OARs of H&N for two beams was under 3%. Brain mean dose, brainstem, and optic chiasm max doses were, respectively, 7.5%–14.9%, 2.2%–8.1%, and 2.5%–19.0% lower for the 2.5 MV beam in the nasal cavity, orbit, and GBM plans. Conclusions This study demonstrates that the 2.5 MV beam can produce clinically relevant treatment plans, motivating future efforts for design of single‐energy LINACs. Such a machine will be capable of producing beams at this energy beneficial for low‐ and middle‐income countries, and investigations on dose enhancement from high‐Z nanoparticles.

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Stability and reproducibility comparisons between deep inspiration breath‐hold techniques for left‐sided breast cancer patients: A prospective study

Parsons

Joo

Iqbal

et al. 2023

J Applied Clin Med Phys

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Deep inspiration breath-hold (DIBH) is crucial in reducing the lung and cardiac dose for treatment of left-sided breast cancer.We compared the stability and reproducibility of two DIBH techniques: Active Breathing Coordinator (ABC) and VisionRT (VRT). Materials and Methods:We examined intra-and inter-fraction positional variation of the left lung. Eight left-sided breast cancer patients were monitored with electronic portal imaging during breath-hold (BH) at every fraction. For each patient, half of the fractions were treated using ABC and the other half with VRT, with an equal amount starting with either ABC or VRT. The lung in each portal image was delineated, and the variation of its area was evaluated. Intrafraction stability was evaluated as the mean coefficient of variation (CV) of the lung area for the supraclavicular (SCV) and left lateral (LLat) field over the course of treatment. Reproducibility was the CV for the first image of each fraction. Daily session time and total imaging monitor units (MU) used in patient positioning were recorded. Results: The mean intrafraction stability across all patients for the LLat field was 1.3 ± 0.7% and 1.5 ± 0.9% for VRT and ABC, respectively. Similarly, this was 1.5 ± 0.7% and 1.6 ± 0.8% for VRT and ABC, respectively, for the SCV field. The mean interfraction reproducibility for the LLat field was 11.0 ± 3.4% and 14.9 ± 6.0% for VRT and ABC, respectively. Similarly, this was 13.0 ± 2.5% and 14.8 ± 9% for VRT and ABC, respectively, for the SCV. No difference was observed in the number of verification images required for either technique. Conclusions: The stability and reproducibility were found to be comparable between ABC and VRT. ABC can have larger interfractional variation with less feedback to the treating therapist compared to VRT as shown in the increase in geometric misses at the matchline.

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Beam generation and planar imaging at energies below 2.40 MeV with carbon and aluminum linear accelerator targets

Cited by 20 publications

References 21 publications

A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinac^a)

A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinac^a)

Treatment planning with a 2.5 MV photon beam for radiation therapy

Stability and reproducibility comparisons between deep inspiration breath‐hold techniques for left‐sided breast cancer patients: A prospective study

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Beam generation and planar imaging at energies below 2.40 MeV with carbon and aluminum linear accelerator targets

Cited by 20 publications

References 21 publications

A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinaca)

A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinaca)

Treatment planning with a 2.5 MV photon beam for radiation therapy

Stability and reproducibility comparisons between deep inspiration breath‐hold techniques for left‐sided breast cancer patients: A prospective study

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A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinac^a)

A Monte Carlo investigation of low‐Z target image quality generated in a linear accelerator using Varianˈs VirtuaLinac^a)