 There he discovered treatments for leukemia and polycythemia by injecting infected mice with radioactive phosphorus derived from the cyclotron invented by his brother, the Nobel Laureate Ernest O. Lawrence.Lawrence pioneered the usage of radioactive tracer techniques to study the impact of disease on metabolic processes.He also demonstrated that neutron beams were potentially more effective at battling cancerous cells than X-rays, and, in 1949, became the first physician to use a radioactively labelled noble gas for diagnostic purposes in humans.