Beam commissioning of the first compact proton therapy system with spot scanning and dynamic field collimation

Objectives: To describe the measurements and to present the results of the beam commissioning and the beam model validation of a compact, gantry-mounted, spot scanning proton accelerator system with dynamic layer-by-layer field collimation. Methods: We performed measurements of depth dose distributions in water, spot and scanned field size in air at different positions from the isocenter plane, spot position over the 20 × 20 cm2 scanned area, beam monitor calibration in terms of absorbed dose to water and specific field collimation measurements at different gantry angles to commission the system. To validate the beam model in the treatment planning system (TPS), we measured spot profiles in water at different depths, absolute dose in water of single energy layers of different field sizes and inversely optimised spread-out Bragg peaks (SOBP) under normal and oblique beam incidence, field size and penumbra in water of SOBPs, and patient treatment specific quality assurance in homogeneous and heterogeneous phantoms. Results: Energy range, spot size, spot position and dose output were consistent at all gantry angles with 0.3 mm, 0.4 mm, 0.6 mm and 0.5% maximum deviations, respectively. Uncollimated spot size (one sigma) in air with an air-gap of 10 cm ranged from 4.1 to 16.4 mm covering a range from 32.2 to 1.9 cm in water, respectively. Absolute dose measurements were within 3% when comparing TPS and experimental data. Gamma pass rates >98% and >96% at 3%/3 mm were obtained when performing 2D dose measurements in homogeneous and in heterogeneous media, respectively. Leaf position was within ±1 mm at all gantry angles and nozzle positions. Conclusions: Beam characterisation and machine commissioning results, and the exhaustive end-to-end tests performed to assess the proper functionality of the system, confirm that it is safe and accurate to treat patients. Advances in knowledge: This is the first paper addressing the beam commissioning and the beam validation of a compact, gantry-mounted, pencil beam scanning proton accelerator system with dynamic layer-by-layer multileaf collimation.

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

Applied Sciences ◽

10.3390/app12020600 ◽

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.

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Preparation of polyelectrolyte multilayer membranes by dynamic layer-by-layer process for pervaporation separation of alcohol/water mixtures

Journal of Membrane Science ◽

10.1016/j.memsci.2006.02.031 ◽

2006 ◽

Vol 280 (1-2) ◽

pp. 727-733 ◽

Cited By ~ 73

Author(s):

Guojun Zhang ◽

Weiliang Gu ◽

Shulan Ji ◽

Zhongzhou Liu ◽

Yuelian Peng ◽

...

Keyword(s):

Layer By Layer ◽

Polyelectrolyte Multilayer ◽

Alcohol Water ◽

Multilayer Membranes ◽

Pervaporation Separation ◽

Dynamic Layer

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Evaluations of polyelectrolyte multilayer membranes assembled by a dynamic layer-by-layer technique

Desalination ◽

10.1016/j.desal.2007.09.098 ◽

2008 ◽

Vol 234 (1-3) ◽

pp. 300-306 ◽

Cited By ~ 18

Author(s):

Shulan Ji ◽

Guojun Zhang ◽

Zhongzhou Liu ◽

Yuelian Peng ◽

Zhan Wang

Keyword(s):

Layer By Layer ◽

Polyelectrolyte Multilayer ◽

Layer Technique ◽

Multilayer Membranes ◽

Layer By Layer Technique ◽

Dynamic Layer

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Dynamic layer-by-layer films on nanofiber membrane: a platform for ultra-sensitive bacterial concentration detection

Chemical Communications ◽

10.1039/c8cc04187c ◽

2018 ◽

Vol 54 (57) ◽

pp. 7920-7923 ◽

Cited By ~ 2

Author(s):

Zhenguo Yu ◽

Zhentan Lu ◽

Yu Huang ◽

Mufang Li ◽

Wenwen Wang ◽

...

Keyword(s):

Layer By Layer ◽

Nanofiber Membrane ◽

Bacterial Concentration ◽

Dynamic Layer

A new platform was established for ultra-sensitive bacterial concentration detection within 5 min.

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Enhanced hollow fiber membrane performance via semi-dynamic layer-by-layer polyelectrolyte inner surface deposition for nanofiltration and forward osmosis applications

Reactive and Functional Polymers ◽

10.1016/j.reactfunctpolym.2014.07.018 ◽

2015 ◽

Vol 86 ◽

pp. 154-160 ◽

Cited By ~ 36

Author(s):

Chang Liu ◽

Lei Shi ◽

Rong Wang

Keyword(s):

Hollow Fiber ◽

Hollow Fiber Membrane ◽

Forward Osmosis ◽

Layer By Layer ◽

Fiber Membrane ◽

Surface Deposition ◽

Membrane Performance ◽

Inner Surface ◽

Dynamic Layer

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Three Dimensional Microstructures from Metal Carbonyls

MRS Proceedings ◽

10.1557/proc-542-31 ◽

1998 ◽

Vol 542 ◽

Author(s):

Jan-Erik Lind ◽

Olli Nyrhila ◽

Juha Kotila ◽

Tatu Syvanen

Keyword(s):

Laser Power ◽

Growth Parameters ◽

Three Dimensional ◽

Spot Size ◽

Layer By Layer ◽

Metal Carbonyls ◽

Power Laser ◽

Iron Carbonyls ◽

Scan Speed ◽

Gas Pressures

Abstract3D-LCVD of nickel and iron carbonyls was studied in order to grow 3-D metal forms under static or scanning Nd:YAG-laser beam. In addition to growth, emphasis was also placed on the prevention of the simultaneous decomposition of carbon monoxide, which interferes with the metal growth process. This was essential, because the fairly high precursor gas pressures of the metal carbonyls are very tempting for the 3D-LCVD. Parameters to be optimized included precursor pressure, laser power, laser scan speed and spot size. In order to optimize the growth parameters, the microstructures of the resulting forms were studied using SEM. Comparison between static and scanning growth is presented with the building philosophy in mind, e.g. whether to build structures layer by layer, from modules or in conjunction with another process to compensate for their shortcomings. The substrates used included steel, graphite and porous bronze.The results indicated different microstructures for iron and nickel, which were dependent on the total/precursor pressure. In the scanning experiments, nickel produced very thin films of high reflectivity, whereas iron produced a structure which could be described as a crystalline spider's web. The static experiments produced solid rods in the case of nickel, whereas with iron, the rods were hollow, even with same spot sizes. Moreover, an evident change in the microstructure of the nickel forms as a function of pressure was observed. The 3-D growth rate of the static experiments seemed very promising for the forthcoming scanning experiments.

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Shape Prediction for Laser Peen Forming of Fiber Metal Laminates by Experimentally Determined Eigenstrain

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4034891 ◽

2016 ◽

Vol 139 (4) ◽

Cited By ~ 4

Author(s):

Zhengyu Zhang ◽

Yongxiang Hu ◽

Zhenqiang Yao

Keyword(s):

Metal Layer ◽

Bending Moment ◽

Approximate Model ◽

Beam Model ◽

Finite Model ◽

Layer By Layer ◽

Fiber Metal Laminates ◽

Shape Prediction ◽

Peen Forming ◽

Fiber Metal

Laser peen forming (LPF) is a promising method to fabricate fiber metal laminates (FMLs) with its design flexibility to produce complex shapes. Eigenstrain-based modeling is a helpful method to predict deformation after LPF, while determining eigenstrain is very difficult because of its complex constituents and high-dynamic loading of process. An effective experiment-based method is proposed in this work to obtain eigenstrain induced by LPF in metal layers of FMLs. An analytical beam model is developed to relate the deflection profile generated by specific scanning strategy to equivalent bending moment. Based on the determined bending moment from the measured deflection profiles, the generated eigenstrain can be inversely calculated by the proposed beam model describing the relationship between the eigenstrain and the bending moment. Chemical etching to remove sheets layer by layer is used to obtain the relaxed deflection profile to calculate the eigenstrain in each metal layer. Furthermore, an approximate model of plate is established to predict deformation after LPF based on determined eigenstrain. The results show that the predictive deformed shape agrees very well with both experiments and finite model prediction.

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