Journal of Medical Physics
 Home | Search | Ahead of print | Current Issue | Archives | Instructions | Subscription | Login  The official journal of AMPI, IOMP and AFOMP      
 Users online: 58  Home  EMail this page Print this page Decrease font size Default font size Increase font size 
Year : 2002  |  Volume : 27  |  Issue : 1  |  Page : 9-21

Characteristics Of Philips SL-20 Linear Accelerator Used For Stereotactic Radiosurgery/ Radiotherapy



Correspondence Address:
Hroid. D Souza


Login to access the Email id

Source of Support: None, Conflict of Interest: None


Rights and PermissionsRights and Permissions

Commissioning of a stereotactic radiosurgery/stereotactic radiotherapy (SRS/SRT) facility on a modified linear accelerator requires validation of mechanical parameters and establishment of parameters, such as tissue maximum ratio (TMR), relative output factors (OF), and off axis ratios (OAR). The mechanical and beam characteristics of Philips SL-20 linear accelerator modified for SRSISRT were evaluated and presented. The SRS/SRT procedure carried on Philips SL-20 linear accelerator with Brown-Robert-Wells (BRW) and relocatable Gill-Thomas-Cosman (GTC) head frames along with the Radionics planning system was evaluated. The tertiary collimator consists of the actual treatment cones and their sizes vary from 12.5 mm to 40 mm diameter. The alignment of the auxiliary collimator axis with mechanical axes and stability of the isocenter of Philips SL-20 machine was evaluated using Iso-Align device and mechanical isocenter standard (MIS). All the mechanical errors of the linear accelerator were within 1 mm, except the stability of the isocenter while rotating the couch. Alignment of auxiliary collimator axis with the central axis, gantry and couch axes were achieved. The TMR, OF and OAR for 6 MV x-rays from Philips SL-20 linear accelerator for different cone sizes were deduced using a Multidata water phantom with 0.015cc chamber. The difference between 50%width of profiles in two major axes (x and y) were within +0.4 mm. The cone dimensions were accurate upto 0.7 mm. The penumbra width for different cones varies from 3.1 mm to 3.5 mm, Dose linearity of the monitoring system was ≤1% above 5 MU. The mechanical and beam characteristics including dose linearity of the SL-20 machine are presented. The beam characteristics of this machine are comparable with the other modified linear accelerators for SRS/SRT. The shift of isocenter during rotation of couch can be nullified by fine adjusting laser target localizing frame to the laser position using micrometer screws along the three directions provided on the couch mount for each arc and hence the unit can be used for SRS/SRT effectively.


[PDF]*
Print this article     Email this article
 Next article
 Previous article
 Table of Contents

 Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Citation Manager
 Access Statistics
 Reader Comments
 Email Alert *
 Add to My List *
 * Requires registration (Free)
 

 Article Access Statistics
    Viewed1097    
    Printed73    
    Emailed2    
    PDF Downloaded154    
    Comments [Add]    

Recommend this journal