Physical Aspects of Eye Plaque Brachytherapy Using Photon Emitters
The current trend toward the use of 125I seed rather than 60Co applicators in the treatment of ocular tumors stems largely from the extent to which photons from the two radionuclides are attenuated differently by plaque material on the one hand and by intraocular tissue on the other. The much lower energies of 125I photons from seeds in a rimmed gold plaque not only permit near-total elimination of radiation dose in orbital tissue adjacent to the plaque but also allow significant dose reduction to critical structures within the eye, relative to either 60Co plaque or proton beam reatment (Fairchild 1984). Although other photon-emitting radionuclides have been used in ophthalmic applicators (Luxton et al. 1988a), we will focus attention here on the physical characteristics of 60Co and 125I applicators because they have been the most widely used and because they illustrate well the pertinent differences between “high energy” and “low energy” photons for this type of brachytherapy.
KeywordsAnisotropy Attenuation Platinum Cobalt Mold
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- Chiu-Tsao ST, Anderson LL, Stabile L (1988) TLD dosimetry for 125I eye plaque. Phys Med Biol 33 [Suppl 1]:128Google Scholar
- Innes G (1962) The application of physics in the treatment of ocular neoplasms. In: Boniuk M (ed) Ocular and adnexal tumors. CV Mosby, St. Louis, p 142Google Scholar
- Interstitial Collaborative Working Group: Anderson LL, Nath R, Weaver KA et al. (1990) Interstitial brachy-therapy: physical, biological and clinical considerations. Raven, New YorkGoogle Scholar
- Rassow J, Strüter H-D, Magnus L, Göbbeler T (1970) Isodosenmessungen an den Kobalt-60-Augenapplikatoren (nach Stallard): allgemeine Berechnung der Tiefendosis für kreisförmige Flächenaktivitäten und die Messung der Isodosen für die Applikatoren CKA 8–11. Radiol Clin Biol 39:32–46PubMedGoogle Scholar
- Schell MC, Weaver KA, Phillips TL, Char DH, Quivey JM, Barnett C, Ling CC (1989) Design of iodine-125 eye plaques for radiation therapy. Endocurietherapy/ Hyperthermia Oncology 5:83–90Google Scholar
- Task Group 32: Nath R, Anderson L, Jones D, Ling C, Loevinger R, Williamson J, Hanson W (1987) Specification of brachytherapy source strength, AAPM Report No. 21. American Institute of Physics, New YorkGoogle Scholar