Automatic Electron Dosimetry System for a Micro wave Linear Accelerator

Radiology ◽  
1966 ◽  
Vol 87 (2) ◽  
pp. 353-353
Author(s):  
Kenneth I. Cook ◽  
Joseph Mantel
Keyword(s):  
Linear Accelerator ◽  
Dosimetry System ◽  
Electron Dosimetry

Commissioning and evaluation of a radiochromic EBT3 film dosimetry system

2018 ◽  
Vol 18 (1) ◽  
pp. 55-62
Author(s):  
Muhammad Isa Khan ◽  
Muhammad Bilal Tahir ◽  
Muhammad Rafique ◽  
Tahir Iqbal ◽  
Sabiha Zulfiqar ◽  
...  
Keyword(s):  
Linear Accelerator ◽  
Cost Effective ◽  
World Health Organisation ◽  
Radiochromic Film ◽  
World Health ◽  
Film Dosimetry ◽  
Photon Beams ◽  
Output Measurement ◽  
Ionisation Chamber ◽  
Dosimetry System

AbstractPurposeThis work reports our study to commission a radiochromic film dosimetry system using the timely EBT3 film. We carried out dosimetric evaluations on different characteristics of photon beams (e.g., flatness, symmetry and penumbra) in radiation dose delivery.Materials and MethodsA Varian linear accelerator producing 6 and 15 MV photon beams with 120 multi-leaf collimator was used in this study. PTW ionisation chamber was used to measure the beam characteristics such as symmetry, flatness and penumbra and these measurements were used to commission the radiochormic EBT3 film dosimetry system. The results of irradiated films were analysed using the radiochromic film QA Pro software 2016.ResultsThe measured film doses were analysed at two different colour channels (green and red) using two scanning geometries (i.e., upper or lower side of film facing the scanner light source) at two dose levels (10 and 40 Gy). The difference between the ionisation chamber and film results was found insignificant and within the acceptable range as per the World Health Organisation standard.ConclusionResults of the comparison between the ionisation chamber and film measurements show that our radiochormic EBT3 film dosimetry system is reliable and cost-effective in the output measurement of a linear accelerator. Our measurements confirm that our EBT3 film dosimetry agreed well with the ionisation chamber, and can be used as a re-validation tool for linear accelerator quality control.

Shaped field electron dosimetry for a Philips SL75/10 linear accelerator

1983 ◽  
Vol 10 (3) ◽  
pp. 356-360 ◽  
Author(s):  
Ravi P. Nair ◽  
T. K. M. Nair ◽  
Don E. Wrede
Keyword(s):  
Linear Accelerator ◽  
Field Electron ◽  
Electron Dosimetry

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

2020 ◽  
Vol 26 (4) ◽  
pp. 235-242
Author(s):  
Mohamad Reza Bayatiani ◽  
Fatemeh Fallahi ◽  
Akbar Aliasgharzadeh ◽  
Mahdi Ghorbani ◽  
Benyamin Khajetash ◽  
...  
Keyword(s):  
Electron Beam ◽  
Linear Accelerator ◽  
Beam Energy ◽  
Field Size ◽  
Surface Distance ◽  
Small Fields ◽  
Dosimetry System ◽  
Electron Beam Radiotherapy ◽  
Effective Source

AbstractObjective: 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.

Small-field electron dosimetry for the Philips SL25 linear accelerator

1990 ◽  
Vol 17 (4) ◽  
pp. 710-714 ◽  
Author(s):  
H. Rashid ◽  
M. K. Islam ◽  
H. Gaballa ◽  
U. F. Rosenow ◽  
J. Y. Ting
Keyword(s):  
Linear Accelerator ◽  
Small Field ◽  
Field Electron ◽  
Electron Dosimetry

scholarly journals Dose non-linearity of the dosimetry system and possible monitor unit errors on medical linear accelerators used in conventional and intensity-modulated radiation therapy

2012 ◽  
Vol 27 (4) ◽  
pp. 368-373 ◽  
Author(s):  
Wazir Muhammad ◽  
Lee Hoon ◽  
Khan Alam ◽  
Muhammad Maqbool ◽  
Gulzar Khan
Keyword(s):  
Radiation Therapy ◽  
Dose Rate ◽  
Linear Accelerator ◽  
Intensity Modulated Radiation Therapy ◽  
Monitor Unit ◽  
Linear Accelerators ◽  
Intensity Modulated ◽  
Dynamic Wedge ◽  
Dosimetry System ◽  
Medical Linear Accelerators

The purpose of this work is to study dose non-linearity in medical linear accelerators used in conventional radiotherapy and intensity-modulated radiation therapy. Open fields, as well as the enhanced dynamic wedge ones, were used to collect data for 6 MV and 15 MV photon beams obtained from the VARIAN linear accelerator. Beam stability was checked and confirmed for different dose rates, energies, and application of enhanced dynamic wedge by calculating the charge per monitor unit. Monitor unit error was calculated by the two-exposure method for open and enhanced dynamic wedge beams of 6 MV and 15 MV photons. A significant monitor unit error with maximum values of ?2.05931 monitor unit and ?2.44787 monitor unit for open and enhanced dynamic wedge beams, respectively, both energy and dose rate dependent, was observed both in the open photon beam and enhanced dynamic wedge fields. However, it exhibited certain irregular patterns at enhanced dynamic wedge angles. Dose monitor unit error exists only because of the overshoot phenomena and electronic delay in dose coincident and integrated circuits with a dependency on the dose rate and photon energy. Monitor unit errors are independent of the application of enhanced dynamic wedge. The existence of monitor unit error demands that the dose non-linearity of the linear accelerator dosimetry system be periodically tested, so as to avoid significant dosimetric errors.

Injector for a 100-500 kV Linac Electron Microscopy Source

1967 ◽  
Vol 25 ◽  
pp. 274-275
Author(s):  
John W. Coleman
Keyword(s):  
Electron Microscopy ◽  
Linear Accelerator ◽  
Beam Current ◽  
Ion Trapping ◽  
University Of Virginia ◽  
Electron Injector ◽  
Illumination System ◽  
Radio Corporation Of America ◽  
The University ◽  
Optical Integration

The injector to be described is a component in the Electron Injector-Linear Accelerator—Condenser Module for illumination used on the variable 100-500kV electron microscope being built at the Radio Corporation of America for the University of Virginia.The injector is an independently powered, autonomous unit, operating at a constant 6kV positive with respect to accelerator potential, thereby making beam current independent of accelerator potential. The injector provides for on-axis ion trapping to prolong filament lifetime, and incorporates a derived Einzel lens for optical integration into the overall illumination system for microscopy. Electrostatic beam deflectors for alignment are an integral part of the apparatus. The entire injector unit is cantilevered off a door for side loading, and is topped with a 4-filament turret released electrically but driven by a self-contained Negator spring motor.

The measurement of photoneutron dose around an 18 MV Varian linear accelerator by TLD600 and TLD700 dosimeters inside the polyethylene sphere of neutron probe LB 6411

2014 ◽  
Vol 6 (1) ◽  
pp. 1049-1057
Author(s):  
Samiei F ◽  
Nedaie H A ◽  
Darestani H ◽  
Banaee N ◽  
Shagholi N ◽  
...  
Keyword(s):  
Linear Accelerator ◽  
Neutron Probe

Bremsstrahlung  X-rays  from  high-energy  linear    accelerators  (Linacs)  produce  neutrons  as  a  result  of  photonuclear  reactions  mainly  with  the  different  materials  constituting  the  accelerator  head.  The  neutrons  produced  during  high  energy  radiotherapy  should  be  considered  in  terms  of  protection  and  ose  escalation.  Due  to  the  very  intense  photon  component  in  the  Linac  field  causing  pulse  pile-up  and  dead-time  effects  in  detectors,  measurement  of  the  corresponding  neutron  dose  by  active  dosimeters  is  extremely  troublesome.  In  this  study,  the  neutron  probe  LB  6411,  which  active  detector  of  3He  proportional  counter  tube  was  replaced  with  the  passive  detectors  of  TLD600  and  TLD700,  has  been  used  to  perform  neutron  measurements  at  four  points  around  the  18  MV  Varian  2100C  Linac  facility.  The  neutron  dose  equivalent  at  the  distance  of  1  and  2  m  from  the  isocentre  on  the  patient  couch  was  obtained  2.2  and  0.75  mSv.Gy-1  respectively.  According  to  the  results,  the  dose  equivalent  from  emitted  photoneutrons  is  not  negligible  and  therefore  treatment  conditions  should  be  optimized.  The  results  of  this  study  emphasized  that  TLD600  and  TLD700  dosimeters  inside  the  polyethylene  sphere  of  neutron  probe  LB  6411  is  an  appropriate  choice  for  studying  photoneutron  production  in  the  vicinity  of  the  accelerator.

Sign in / Sign up

Export Citation Format

Share Document