Space Radiation Physics

Simulation

The space radiation environment is complex and different from anything typically experienced at the surface of the Earth. This radiation poses a risk to astronauts and NASA has an extensive research program to assess the details of the risks of such exposures. One important physics issue is the determination of the exact radiation field that astronauts bodies will experience in a variety of environments from inside interplanetary spacecraft to habitats on the surface of the Moon and Mars. The primary external radiation will be fragmented and moderated by its traversal through the intervening shielding material of spacecraft and spacesuit structures as well as from the interactions within the astronaut's own bodies. The mechanism to predict the relevant environments is to employ computer simulations. Prof. Pinsky is member of the FLUKA Collaboration, based at CERN and INFN Milan, Italy. FLUKA is a "Monte Carlo" transport code, and it can be used to evaluate dosimetric values for exposures in space radiation situations.

Dosimetry

The University of Houston is a member of the Medipix2 Collaboration, which is based at CERN. Medipix is a pixel-based detector technology that is useful for both x-ray imaging and for charge particle detection. Prof. Pinsky is working on the development of a version of this technology that can be used as a dosimeter in the space radiation environment. Such a device can be made as small as the conventional radiation "film badges" and can even be made "wireless" to allow remote real-time monitoring of the radiation field. Versions that might be built into the space suits as well as mounted as area monitors in spacecraft and habitats are being developed.

Cancer Radiotherapy

Planning

The advent of the use of accelerated beams of charged particles to treat cancer tumors has become more widespread in recent years, including the use of heavy ion beams such as carbon in place of protons. In each case, the patient is given a CT-Scan to identify the tumor location and to assess the normal surrounding tissue that the beams must pass through to reach the tumor. Particle transport calculations are then used to simulate the beams and to determine the beam energies necessary to reach the tumor from several different directions. The FLUKA transport code is one of the programs used to simulate the treatment and to make up the treatment plans. Dr. Pinsky is a member of the FLUKA Collaboration, which is based at CERN and at INFN in Milan, Italy. The FLUKA code is capable of predicting the detailed interactions of the beam as it passes through the patient's body and to provide a map of the expected production of radioactive isotopes along its path, such as Carbon-11 and Oxygen-15, which are positron emitters, and which can be observed directly with a PET camera.

Monitoring

Once the treatment planning has predicted the location of the positron emitters that will be produced along the beam's path through the body, the actual treatment can be monitored to verify that the dose is being delivered to the desired regions of tissue. The beams can be actively monitored as well using the Medipix2 technology, which is being developed by the University of Houston Medipix group. The University of Houston is a member of the Medipix2 Collaboration, which is based at CERN. Medipix is a pixel-based detector technology that is useful for both x-ray imaging and for charge particle detection. Prof. Pinsky is working on the development of a version of this technology that can be used to monitor cancer radiotherapy beams.