Detection of the focal spot motion relative to the collimator axis of a linear accelerator under gantry rotation

2019 ◽  
Vol 64 (3) ◽  
pp. 03NT02
Author(s):  
Hans L Riis ◽  
Martin A Ebert ◽  
Pejman Rowshanfarzad
Keyword(s):  
Linear Accelerator ◽  
Focal Spot ◽  
Spot Motion

Focal spot motion of linear accelerators and its effect on portal image analysis

2003 ◽  
Vol 30 (6) ◽  
pp. 1067-1075 ◽  
Author(s):  
Jan-Jakob Sonke ◽  
Bob Brand ◽  
Marcel van Herk
Keyword(s):  
Image Analysis ◽  
Focal Spot ◽  
Linear Accelerators ◽  
Spot Motion

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.

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

Computational Technique for the Qualification of Focal Spot Size and Shape of Industrial Radioscopy Equipment Using Star Patterns

2020 ◽  
Vol 78 (4) ◽  
pp. 479-486
Author(s):  
Marcela Tatiana Fernandes Beserra ◽  
◽  
Ricardo Tadeu Lopes ◽  
Davi Ferreira de Oliveira ◽  
Claudio Carvalho Conti ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Computational Technique ◽  
Focal Spot Size ◽  
Size And Shape

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