Computational phantom for red bone marrow dosimetry from incorporated beta emitters in a newborn baby

Abstract

Active (red) bone marrow (AM) exposure due to ingested bone-seeking radionuclides can lead to grave medical consequences. For example, a radioactive contamination of the Techa River in the 1950s caused exposure to AM for riverside residents and led to chronic radioactive exposure syndrome in some of them, with higher risk of leukemia. The main sources of the marrow exposure were the bone-seeking beta emitters 89,90Sr. Improving the dosimetry of AM internal exposure is an important step in clarifying the risks of chronic radiation exposure for riverside residents. To evaluate the energy absorbed by AM from incorporated 90Sr it is customary to use computational phantoms where radiation transport can be emulated. A phantom is a representative digital representation of skeletal bone geometry and AM The goal of this work was to develop a computational phantom of a newborn skeleton for dosimetry of AM from incorporated 90Sr. The researchers have used the Stochastic Parametric Skeletal Dosimetry method (SPSD), where hematopoietic sites were modeled as a set of phantoms of simple geometric shape describing individual skeletal bone areas. The AM content in the skeleton as well as the phantom parameters were evaluated on the basis of published measurements of real bones. As a result, a computational phantom of the main skeletal hematopoietic sites was generated for a newborn baby, including 34 phantoms of bone areas. The simulated phantom simulates the bone structure as well as the variability of skeletal parameters within the population and corresponds well to measurements of real bones.