Advertisement

Clinical Electron Beam Physics

  • Francis J. Bova
Chapter
Part of the Medical Radiology book series (MEDRAD)

Abstract

As in all treatment planning, the aim of the procedure is to derive a plan for irradiating the target tissues while ensuring optimum sparing of nontarget tissues. With photon beam planning, the beam is exponen­tially absorbed by the tissues beyond the target depth, whereas the finite range of electrons provides a powerful tool for limiting the dose to deep-seated tissues. As always, with any advantage comes disad­vantage. With electrons, these disadvantages involve the rapid decrease in field uniformity as one moves farther away from the point of final collimation. With electrons, one also experiences rapid and significant changes in the depth-dose curves for very small field sizes, and the rapid change in depth of dose penetration when traversing inhomogeneities. There are also difficulties in accurately predicting a virtual source position and subsequently predicting output at extended source-to-surface distances (SSDs). Furthermore, output for irregularly shaped fields is difficult to predict.

Keywords

Electron Beam Dose Distribution Field Size Output Factor Surface Dose 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Abolghassem J, Kuchnir FT, Reft CS (1986) Determination of the source position for the electron beams from a high-energy linear accelerator. Med Phys 13: 942–948CrossRefGoogle Scholar
  2. Abou Mandour M, Harder D (1978) Systematic optimization of the double-scatter system for electrons beam field-flattening. Strahlentherapie 154: 328–332Google Scholar
  3. Berger MJ, Seltzer SM (1981) Fundamental aspects of ab­sorbed dose measurement. Proceedings of the Symposium on Electron Dosimetry and Arc Therapy.pp 1–19Google Scholar
  4. Biggs P (1984) The effect of beam angulation on central axis percent depth dose for 4–29 MeV electrons. Phys Med Biol 29:1089–1096PubMedCrossRefGoogle Scholar
  5. Biggs PJ, Boyer AL, Doppke KP (1979) Electron dosimetry of irregular fields on the Clinac 18. Int J Radiat Oncol Biol Phys 5:433–440PubMedCrossRefGoogle Scholar
  6. Bjarngard BF, Piontek RW, Svensson GK (1976) Electron scattering and collimation system for a 12 MeV linear accel­erator. MedPhys 3:153–158Google Scholar
  7. Boag JW (1972) Surface ionization ratio for electrons in the energy range 3 to 11 MeV. Br J Radiol 45:229PubMedCrossRefGoogle Scholar
  8. Bova FJ (1990) A film phanton for routine film dosimetry in the clinical environment. Med Dosim 15:83–85PubMedGoogle Scholar
  9. Bova FJ (1994) Treatment planning for irradiation of head and neck cancer. In Million RR, Cassisi NJ (eds) Cancer of the head and neck : a multidisciplinary approach. Philadelphia, Lippincott, pp 209–230Google Scholar
  10. Bruinvis IAD, Mathol WAF (1988) Calculation of election beam depth-dose curves and output factors for arbitrary field shapes. Radiother Oncol 11:395–404PubMedCrossRefGoogle Scholar
  11. Dutreix J, Dutreix A (1969) Film dosimetry of high energy electrons. Ann NY Acad Sci 161:33–42PubMedCrossRefGoogle Scholar
  12. Galbraith DM , Rawlinson JA, Munro P (1984) Dose errors due to charge storage in electron irradiated plastic phan­toms. Med Phys 11:197–203PubMedCrossRefGoogle Scholar
  13. Giarratano JC, Duerkes RJ, Almond PR (1975) Lead shield­ing thickness for dose reduction of 7- to 28-MeV electrons. Med Phys 2:336–338PubMedCrossRefGoogle Scholar
  14. Hogstrom KR, Almond PR (1983) Comparison of experi­mental and calculated dose distributions. Acta Radiol Supl (Stockh) 364:89–99Google Scholar
  15. International Commission on Radiation Units and Measurements: ICRU Report 21 (1972) Radiation dosime­try: electrons with initial energies between 1–50 MeV. Washington, DCGoogle Scholar
  16. Kerst DW (1943) The betatron. Radiology 40:115–119Google Scholar
  17. Khan FM (1984) The physics of radiation therapy. Williams & Wilkins, Baltimore, pp 320 and 322Google Scholar
  18. Khan FM, Werner BL, Deibel FC Jr (1981) Lead shielding for electrons. Med Phys 8:712–713PubMedCrossRefGoogle Scholar
  19. Khan FM, Doppke KP, Hogstrom KR et al. (1991) Clinical elec­tron-beam dosimetry: Report of AAPM Radiation The­rapy Committee Task Group No. 25. Med Phys 18:73–109PubMedCrossRefGoogle Scholar
  20. Klevenhagen SC, Lambert GD, Arbabi A (1982) Back-scattering in electron beam therapy for energies between 3 and 35 MeV. Phys Med Biol 27:363–373PubMedCrossRefGoogle Scholar
  21. Lax I, Brahme A (1980) Collimation of high energy electron beams. Acta Radiol (Oncol) 19:119–207Google Scholar
  22. McGinley PH, McLaren JR, Barnett BR (1979) Small electron beams in radiation therapy. Radiology 131: 231–234PubMedGoogle Scholar
  23. McParland BJ (1987) A parametrization of the electron beam output factors of a 25-MeV linear accelerator. Med Phys 14: 665–669PubMedCrossRefGoogle Scholar
  24. Meyer JA, Palta JR, Hogstrom KR (1984) Demonstration of relatively new electron dosimetry measurement techniques on the Mevatron 80. Med Phys 11:670–677PubMedCrossRefGoogle Scholar
  25. Miller CW (1954) An 8 MeV linear accelerator for x-ray thera­py. Proc IEE 101:207–222Google Scholar
  26. Mills MD, Hogstrom KR, Almond PR (1982) Prediction of electron beam output factors. Med Phys 9:60–68PubMedCrossRefGoogle Scholar
  27. Palta JR, Daftari IK, Ayyangar KM, Suntharalingam N (1990) Electron beam characteristics on a Philips SC25. Med Phys 17:27–34PubMedCrossRefGoogle Scholar
  28. Skaggs LS, Almy GM, Kerst DW, LanzlLH (1948) Development of the betatron for electron therapy. Radiology 50:167–173PubMedGoogle Scholar
  29. Sternick E (1978) Algorithms for computerized treatment planning. In: Orton CG, Bagne F (eds) Practical aspects of electron beam treatment planning. Medical physics monograph No.2, p 52. American Institute of Physics, New YorkGoogle Scholar
  30. Sweeney LE, Gur D, Bukovitz AG (1981) Scatter component and its effect on virtual source and electron beam quality. Int J Radiat Oncol Biol Phys 7:967–971PubMedCrossRefGoogle Scholar
  31. Task Group 21, Radiation Therapy Committee, American Association of Physicists in Medicine (1983) A protocol for the determination of absorbed dose from high-energy photon and electron beams. Med Phys 10:741–771CrossRefGoogle Scholar
  32. Turner AP (1980) Surface dose measurements clinac 18 electron beams. Proceedings Eight Varian Clinac Users Meeting, January 31-February 2Google Scholar
  33. Udale M (1988) A Monte Carlo investigation of surface doses for broad electron beams. Phys Med Biol 33:939–954CrossRefGoogle Scholar
  34. van der Laarse R, Bruinvis IAD, Nooman MF (1978) Wall-scattering effects in electron beam collimation. Acta Radiol Oncol 17:113–124CrossRefGoogle Scholar
  35. White DR, Martin RJ, Darlison R (1977) Epoxy resin based tissue substitutes. Br J Radiol 50:814–821PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1995

Authors and Affiliations

  • Francis J. Bova
    • 1
  1. 1.Department of Radiation OncologyUniversity of FloridaGainesvilleUSA

Personalised recommendations