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1

Determination of effective source to surface distance and cutout factor in small fields in electron beam radiotherapy: A comparison of different dosimeters

Bayatiani Mohamad Reza, Fallahi Fatemeh, Aliasgharzadeh Akbar, Ghorbani Mahdi, Khajetash Benyamin, Seif Fatemeh

Polish Journal of Medical Physics and Engineering

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2020

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Vol. 26, Iss. 4

235--242

EN

Objective: The main purpose of this study is to calculate the effective source to surface distance (SSDeff) of small and large electron fields in 10, 15, and 18 MeV energies, and to investigate the effect of SSD on the cutout factor for electron beams a linear accelerator. The accuracy of different dosimeters is also evaluated. Materials and methods: In the current study, Elekta Precise linear accelerator was used in electron beam energies of 10, 15, and 18 MeV. The measurements were performed in a PTW water phantom (model MP3-M). A Semiflex and Advanced Markus ionization chambers and a Diode E detector were used for dosimetry. SSDeff in 100, 105, 110, 115, and 120 cm SSDs for 1.5 × 1.5 cm2 to 5 × 5 cm2 (small fields) and 6 × 6 cm2 to 20 × 20 cm2 (large fields) field sizes were obtained. The cutout factor was measured for the small fields. Results: SSDeff in small fields is highly dependent on energy and field size and increases with increasing electron beam energy and field size. For large electron fields, with some exceptions for the 20 × 20 cm2 field, this quantity also increases with energy. The SSDeff was increased with increasing beam energy and field size for all three detectors. Conclusion: The SSDeff varies significantly for different field sizes or cutouts. It is recommended that SSDeff be determined for each electron beam size or cutout. Selecting an appropriate dosimetry system can have an effect in determining cutout factor.

2

The effect of external wedge on the photoneutron dose equivalent at a high energy medical linac

Hashemi , S. M., Raisali G., Taheri M., Majdabadi A., Ghafoori M.

Nukleonika

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2011

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Vol. 56, No. 1

49-51

EN

Medical linacs used in radiotherapy produce bremsstrahlung spectra. In the energy range from 8 to 25 MV medical linacs produce, besides the clinically useful electron and photon beams, secondary neutrons. The aim of this study was to investigate the effect of an external wedge filter on the photoneutron dose equivalent produced by a medical linac at patient plane. Polycarbonate (PC) films were used for the determination of photoneutron dose equivalent produced by a Varian 2100 C/D linac working at 18 MV photon mode. Neutron dose equivalent was measured at distances 0, 10, 20 and 50 cm from the center of the X-ray beam for open field and after inserting a wedge filter. It was noted that by inserting the external wedge in the path of the X-ray beam, the photoneutron dose equivalent was increased compared to open field. It can be concluded that an external wedge, made from heavy materials may act like the other components of linac head, producing undesired photoneutrons and thus increasing patient dose.

3

Monte Carlo modeling of electron beams from a NEPTUN 10PC medical linear accelerator

Jabbari N., Hashemi-Malayeri B.

Nukleonika

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2009

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Vol. 54, No. 4

233-238

EN

The Monte Carlo (MC) simulation of radiation transport is considered to be one of the most accurate methods of radiation therapy dose calculation. With the rapid development of computer technology, MC-based treatment planning for radiation therapy is becoming practical. A basic requirement for MC treatment planning is a detailed knowledge of radiation beams of medical linear accelerators (linacs). A practical approach to acquire this knowledge is to perform MC simulation of radiation transport for linacs. The aims of this study were: modeling of the electron beams from the NEPTUN 10PC linear accelerator (linac) with the MC method, obtaining of the energy spectra of electron beams, and providing the phase-space files for the electron beams of this linac at different field sizes. Electron beams produced by the linac were modeled using the BEAMnrc MC system. Central axis depth-dose curves and dose profiles of the electron beams were measured experimentally and also calculated with the MC system for different field sizes and energies. In order to benchmark the simulated models, the percent depth dose (PDD) and dose-profile curves calculated with the MC system were compared with those measured experimentally with diode detectors in an RFA 300 water phantom. The results of this study showed that the PDD and dose-profile curves calculated by the MC system using the phase-space data files matched well with the measured values. This study demonstrates that the MC phase-space data files can be used to generate accurate MC dose distributions for electron beams from NEPTUN 10PC medical linac.

4

Free Electron Laser in Poland

Romaniuk R. S.

Electronics and Telecommunications Quarterly

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2009

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Vol. 55, No 4

669-682

EN

The idea of building a new IVth generation of light sources of high luminosity, which use accelerators, arose in the 80ties of XXth century. Now, in a numerable synchrotron and laser laboratories in Europe, an intense applied research on free electron lasers has been carried out for a couple of years (FEL) [17,18]. Similarly, in this country, free electron laser in Poland - POLFEL [9] is in a design, a coherent light source of the IVth generation, characterized by very short pulses in the range of 10-100fs, of big power 0,2GW and UV wavelength of 27nm, of average power 1W, with effective high power third harmonic of 9nm. The laser consists of a linear superconducting accelerator 100m in length, undulator and experimental lines. It generates a monochromatic and coherent radiation and can be tuned from THz range via IR, visible to UV, and potentially to X-rays. The linac works in quasi-CW or real-CW mode. It is planned by IPJ [9,10] and XFEL-Poland Consortium [16] as a part of the ESFRI [1] priority Euro FEL infrastructure collaboration network [6], part of the European Research Area - ERA [2]. The paper discusses: FEL background in Poland as a part of EuroFEL infrastructure, FEL parameters and performance, FEL research and technical program and FEL networking in Europe and worldwide. Emphasis is put on the usage of superconducting RF TESLA technology and ties linking Polfel and the European X-Ray Free Electron Laser. The Polfel team of researchers is now dissipated worldwide among such projects as Flash and E-xfel in Desy, Cebaf in JLab, Alba in Barcelona, Elettra in Trieste, ILC in Fermilb, LCLS in SLAC. Polfel creates an unique, but quite transient chance to gather and solidly accumulate for a long time this expertise in this country again.

5

EuCARD i CARE : rozwój techniki akceleratorowej w Polsce

Romaniuk R.

Elektronika : konstrukcje, technologie, zastosowania

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2008

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Vol. 49, nr 10

12-17

PL

Rozwój techniki akceleratorowej w Polsce jest ściśle powiązany ze współpracą ze specjalistycznymi ośrodkami dysponującymi akceleratorami na świecie. gdzie jest generowana odpowiednia wiedza pozwalająca na budowę dużych i nowoczesnych maszyn. Są to przedsięwzięcia relatywnie kosztowne o charakterze interdyscyplinarnym. Znaczna część z nich jest finansowana lokalnie. Tylko największe maszyny są finansowane wspólnie przez wiele państw jak LHC w Cernie. ILC w Fermilabie i E-XFEL w Desy. Podobnie musi być w Polsce, gdzie trwa obecnie kampania naukowa i polityczna na rzecz budowy dwóch dużych maszyn: Polskiego Synchrotronu w Krakowie oraz Polskiego lasera na swobodnych elektronach POLFEL w Świerku. Wokół tych dwóch bardzo dużych projektów naukowo-technicznych realizowanych jest kilkadziesiąt mniejszych.

EN

The development of accelerator technology in Poland is strictly combined with the cooperation with specialised accelerator centers of global character, where the relevant knowledge is generated, allowing to build big and modern machines. These are relatively costly undertakings of interdisciplinary character. Most of them are financed by the local resources. Only the biggest machines are financed commonly by many nations like: LHC in Cern, ILC in Fermi Lab, E-XFEL in Desy. A similar financing solution has to be implemented in Poland, where a scientific and political campaign is underway in behalf of building two big machines, a Polish Synchrotron in Kraków and a Polish FEL in Świerk. Around these two projects, there are realized a dozen or so smaller ones.

6

Development of accelerator technology in Poland Impact of European CARE and EuCARD programs

Romaniuk R. S.

Electronics and Telecommunications Quarterly

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2008

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Vol. 54, No 3

239-251

EN

The development of accelerator technology in Poland is strictly combined with the cooperation with specialist accelerator centers of global character, where the relevant knowledge is generated, allowing to build big and modern machines. These are relatively costly undertakings of interdisciplinary character. Most of them are financed from the local resources. Only the biggest machines are financed commonly by many nations like: LHC in CERN, ILC in Fermi Lab, E-XFEL in DESY. A similar financing solution has to be implemented in Poland, where a scientific and political campaign is underway on behalf of building two big machines, a Polish Synchrotron in Kraków and a Polish FEL in Świerk. Around these two projects, there are realized a dozen or so smaller ones.

7

A study of the photoneutron dose equivalent resulting from a Saturne 20 medical linac using Monte Carlo method

Hashemi F., Hashemi-Malayeri B., Raisali G., Shokrani P., Sharafi A.

Nukleonika

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2007

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Vol. 52, nr 1

39-43

EN

High energy linacs have several advantages including lower skin dose and higher dose rate at deep sighted tumors. But, at higher energies photonuclear reactions produce neutron contamination. Photoneutron contamination has been investigated from the early days of modern linacs. However, more studies have become possible using Monte Carlo codes developed in recent years. The aim of this study was to investigate the photoneutron spectrum and dose equivalent produced by an 18 MV Saturne linac at different points of a treatment room and its maze. The MCNP4C code was used to simulate the transport of photoneutrons produced by a typical 18 MV Saturne linac. The treatment room of a radiotherapy facility in which a Saturne 20 linac is installed was modeled. Neutron dose equivalent was calculated and its variations at various distances from the center of the X-ray beam was studied. It was noted that by increasing the distance from the center of the beam, fast neutrons decrease rapidly, but thermal neutrons do not change significantly. In addition, the photoneutron dose equivalent was lower for smaller fields. The fast photoneutrons were not recorded in the maze. It can be concluded that the fast photoneutrons are highly attenuated by concrete barrier, while the slow photoneutrons are increased. In addition, increasing the X-ray field size increases the photoneutron dose equivalent around the treatment room and maze. It seems that the walls play an effective role in increasing the photoneutron dose equivalent.

8

Recent achievements at TRIUMF

Dutto G.

Nukleonika

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2003

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Vol. 48,suppl.2

159-163

EN

A new series of experiments (mainly in astrophysics) began at TRIUMF in July 2001 when the ISAC-I linear accelerator started delivering radioactive ion beams (RIB) of energy up to 1.5 MeV/u. Since then the linac has operated reliably. Required improvements demand care during scheduled maintenance. More difficult was the smooth production of RIB with a 500 MeV proton beam on different target materials, where state-of-the-art techniques are being learned. Targets of CaO, Ta, SiC, Nb, and CaZrO3 have been used in combination with a surface ion source and incident proton currents up to 40 žA. Record radioactive beam intensities were achieved. A second target station is now being commissioned and will become operational during the fall of 2002. A superconducting linear accelerator extending the RIB energy to 6.5 MeV/u has recently been approved and is now being constructed (ISAC-II). A new 3500 m2 experimental building is being erected. A charge state booster, which will extend the mass range of the accelerated ions from A ? 30 to A ? 150, is also being commissioned. The 500 MeV cyclotron is being refurbished for reliability and upgraded to higher currents. A suitable operational beam tune for a total H- accelerated beam current of 300 žA has been commissioned and is now available to supply beam to four separate extraction proton lines simultaneously.