Electron beam characteristics at extended source to surface distance for a Clinac-DHX linear accelerator

• Authors: T. Arunkumar , Sanjay Supe , M. Ravikumar , S. Sathiyan , K. Ganesh , C. Varatharaj
• Languages of publication: EN

Abstracts

EN

A uniform dose to the target site is required with a knowledge of delivered dose, central axis depth dose and beam flatness for successful electron treatment at an extended source to surface distance (SSD). In an extended SSD treatment under dosage of the lateral tissue may occur due to reduced beam flatness. To study the changes in beam characteristics, the depth dose curves, beam flatness and isodose distributions were measured at different SSDs from 100 to 120 cm for clinically used field sizes from (4×4) to (25×25) cm2 and beam energies ranging from 6 MeV to 20 MeV. Our results suggest that the change in depth dose is minimal except in the buildup region for most energy. In general surface dose is decreased as the SSD increased moderately. It was observed that the loss in beam flatness is significant for smaller fields, higher isodose lines, and lower energies. The penumbra enlarged and the uniformity index reduced with increasing SSD.

Keywords

EN

electron beam; beam flatness; uniformity index; beam penumbra; isodose

• Publisher: Versita
• Journal: Polish Journal of Medical Physics And Engineering
• Year: 2009
• Volume: 15
• Issue: 3
• Pages: 121-133

Dates

published

1 - 1 - 2009

online

22 - 9 - 2010

Contributors

author

T. Arunkumar

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

Sanjay Supe

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

M. Ravikumar

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

S. Sathiyan

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

K. Ganesh

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

author

C. Varatharaj

• Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India

References

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• International Electro technical Commission, Report 35-I and 35-II. Medical electrical equipment, Medical Electron Accelerator, Section IV: Functional performance characteristics and report 1984.
• Khan FM, Doppke KP, Hogstrom KR, Kutcher GJ, Nath R, Prasad SC, et al. Clinical electron-beam dosimetry: report of AAPM Radiation Therapy Committee Task Group No. 25. Med Phys. 1991; 18: 73-109.[Crossref]
• Saw CB, Ayyangar KM, et al. Dose distribution considerations of medium electron beams at extended source to surface distance. Int J Radiat Oncol Biol Phys 1995; 32: 159-164.[PubMed]
• Saw CB, Pawlicki T, Korb LJ, Wu A. Effects of extended SSD on electron beam depth-dose curves. Med Dosim. 1994; 19: 77-81.[PubMed]

Identifiers

DOI

10.2478/v10013-009-0012-x