Radiotoxicity of Gadolinium-148 and Radium-223 in Mouse Testes: Relative Biological Effectiveness of Alpha-Particle Emitters In Vivo

• Published in: Radiation research Vol. 147; no. 3; pp. 342 - 348
• Main Authors: Howell, Roger W., Goddu, S. Murty, Narra, Venkat R., Fisher, Darrell R., Schenter, Robert E., Rao, Dandamudi V.
• Format: Journal Article
• Language: English
• Published: Oak Brook, Il Radiation Research Society 01-03-1997
• Subjects: Alpha Particles; Animals; Augers; Biological and medical sciences; Biological effects of radiation; Dose response relationship; Dose-Response Relationship, Radiation; Dosimetry; Fundamental and applied biological sciences. Psychology; Gadolinium - toxicity; Ionizing radiations; Male; Mice; Radiation dosage; Radioactive decay; Radioisotopes - toxicity; Radionuclides; Radium - toxicity; Relative biological effectiveness; Solar X rays; Sperm Head - radiation effects; Spermatogenesis - radiation effects; Spermatozoa; Testes; Testis - radiation effects; Tissues, organs and organisms biophysics; Spermatogenesis; Toxicity; Rodentia; Relative biological effectiveness; Gadolinium; Radioisotope; Experimental study; Radiotherapy; Testicle; Alpha emitter; Energy level; Linear energy transfer; In vivo; Vertebrata; Mammalia; Treatment; Mouse; Animal; Immunotherapy; Dosimetry; Survival curve; Radium
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3579342

The biological effects of radionuclides that emit α particles are of considerable interest in view of their potential for therapy and their presence in the environment. The present work is a continuation of our ongoing effort to study the radiotoxicity of α-particle emitters in vivo using the survival of murine testicular sperm heads as the biological end point. Specifically, the relative biological effectiveness (RBE) of very low-energy α particles (3.2 MeV) emitted by ^{148}{\rm Gd}$ is investigated and determined to be 7.4 ± 2.4 when compared to the effects of acute external 120 kVp X rays. This datum, in conjunction with our earlier results for 210 Po and ^{212}{\rm Pb}$ in equilibrium with its daughters, is used to revise and extend the range of validity of our previous RBE-energy relationship for α particles emitted by tissue-incorporated radionuclides. The new empirical relationship is given by ${\rm RBE}_{\alpha}=9.14-0.510\ {\rm E}_{\alpha}$, where $3<{\rm E}_{\alpha}<9\ {\rm MeV}$. The validity of this empirical relationship is tested by determining the RBE of the prolific α-particle emitter ^{223}{\rm Ra}$ (in equilibrium with its daughters) experimentally in the same biological model and comparing the value obtained experimentally with the predicted value. The resulting RBE values are 5.4 ± 0.9 and 5.6, respectively. This close agreement strongly supports the adequacy of the empirical ${\rm RBE}\text{-}{\rm E}_{\alpha}$ relationship to predict the biological effects of α-particle emitters in vivo.