A Comparison of Cs-137 γ Rays and 320-kV X-Rays in a Mouse BoneMarrow Transplantation Model

摘要

US homeland security concerns regarding the potential misuse of some radiationsources used in radiobiological research, for example, cesium-137( Cs), have resulted in recommendations by the NationalResearch Council to conduct studies into replacing these sources with suitableX-ray instruments. The objective of this research is to compare theeffectiveness of an X-RAD 320 irradiator (PXINC 2010) with a Csirradiator (Gammacell-1000 Unit) using an established bone marrow chimericmodel. Using measured radiation doses for each instrument, we characterized thedose–response relationships for bone marrow and splenocyte ablation, using acytotoxicity-hazard model. Our results show that the X-RAD 320 photon energyspectrum was suitable for ablating bone marrow at the 3 exposure levels used,similar to that of Cs photons. However, the 320-kV X-rays were notas effective as the much higher energy γ rays at depleting mouse splenocytes.Furthermore, the 3 X-ray levels used were less effective than the higher energyγ rays in allowing the successful engraftment of donor bone marrow, potentiallyas a result of the incomplete depletion of the spleen cells. More definedstudies are warranted for determining whether bone marrow transplantation inmice can be successfully achieved using 320-kV X-rays. A higher X-ray dose thenused is likely needed for transplantation success.