Galactic Dosimetry and Ground-based Health
Stephen B. Guetersloh
Practical Physics Solutions, LLC
Increases in the duration of crewed space missions, and the likelihood of missions outside Low-Earth Orbit (LEO), are driving the need for a deeper understanding of the health effects of space radiation so that the risks to personnel can be better managed. The highly energetic ions of the Galactic Cosmic Ray (GCR) environment can penetrate many g/cm2 of matter, but because of payload constrains shielding is, and will be, limited. A better understanding of the long-term risk associated with these highly penetrating particles, once thought to be a focus only of NASA, is also becoming necessary for ground based applications. The beneficial medical use of highly energetic heavy charged particles was first proposed in the mid 1940’s but studies did not start until the late 1980’s at LBL’s Bevalac, where heavy ions were studied as a tumor treatment modality. Clinical therapy using beams of protons was undertaken by Loma Linda University in the early 1990’s, and in 1994 Japan began clinical studies using carbon as a non-invasive tumor treatment modality, followed shortly at GSI in Germany. Still there remains little human exposure data and derived risk carries large uncertainties. Charged particle interactions in tissue, as well as tissue and organism response, must be fully understood for optimal treatment planning and treatment delivery. To gain a better understanding on the nature of the problem, the sources of these uncertainties are presented.