"Thorium-232, the most abundant thorium isotope, is highly radiopaque and produces excellent subject contrast due to its high atomic number (Z=90) relative to biological tissues, resulting in differential photoelectric absorption 7. It is an alpha emitter, decaying to radium-228, with a physical half-life of 1.405 x 1010 years and an estimated biological half-life of 400 years 8. Its distribution within the body varies according to administration route but when administered intravascularly, it is predominantly retained within the reticuloendothelial system (liver, spleen, bone marrow, and lymph nodes) 8. Its use is associated with an increased risk of malignancy but ironically, its initial popularity was in part due to its perceived safety 7,8."
"Thorotrast was the trade name of a radioactive thorium dioxide suspension radiographic contrast media widely used between the 1930s and 1940s. It was popular as an intravascular contrast agent, particularly for cerebral angiography. An estimated 2-10 million people have received it 8. Umbrathor was another thorium dioxide-based contrast medium that was principally used to assess the GI tract."
Expected headings
"Physics"
"History"
"Complications"