A solar flare simulation and dosimetry facility at a proton therapy cyclotron

Abstract

During extravehicular activities (EVA) astronauts are exposed to intense radiation from solar flare events (SFE). Hence, the radiation shielding efficacy of space suits, in particular the helmets and extra vehicular visor assembly (EVVA) are imperative to safety of astronauts and ultimate success of the space mission. At West German Proton Therapy Centre Essen (WPE) we have replicated the historical solar flare spectra by manipulating the treatment planning system (TPS) of the 230 MeV proton-therapy cyclotron and developed novel proton irradiation and dosimetry methods for the testing of space borne devices as mentioned above. We have used a single foil of radiochromic film (type EBT 2) to estimate the proton depth dose distribution in the human eye. The optimal thickness of EVVA (acryl glass) for the protection from solar flares was estimated to be 2.35 cm. A maximum SFE proton dose up to 20 Gy found to be well assessed using the EBT 2 films.

Feasibility study of a proton fluence monitor for LEO-Nanosatellite missions based on displacement damage induced in GaAs-LED

“…Table 1. Showing the lower and upper proton energy steps (figure 3), non-ionising energy loss (NIEL GaAs ) in Gallium Arsenide (GaAs) [19] and normalised proton fluence φ E relevant to 180 MeV mono energetic protons from medical cyclotron [20] and AP8-Max and AP8-Min proton models adopted from NASA database [23,24].…”

“…The selected GAL pieces with similar optoelectronic properties (±5% standard deviation) were irradiated with 180 MeV mono-energy proton beam from space radiation simulation and testing facility [20] of West German Proton Therapy Centre Essen (WPE) operating a 235 MeV roomtemperature proton cyclotron as follows: (a) Six GAL samples were individually packed in small light-tight (dark) PVC pouches. (b) The seventh GAL was kept as control.…”

“…Proton depth dose distribution (figure 5) was calculated using the stopping power data tables [22] and presented equation (2.6). The technique of proton dose delivery equation (2.6) and resulting fluence calculation equation (2.7) formulae are embedded in the TPS software routinely used at WPE [20]. Proton beam was monitored in real-time by the ion-chamber (MU counter) integrated to beam delivery nozzle (figure 4a) [21].…”

“…Figure 5. Depth dose distribution of 180 MeV protons in polystyrene[20] calculated using the SRIM code[22].…”