How air influences radiation dose deposition in multiwell culture plates: a Monte Carlo simulation of radiation geometry.
Bottom Line: Radiation of experimental culture cells on plates with various wells can cause a risk of underdosage as a result of the existence of multiple air-water interfaces.Radiation conditions were simulated with the GAMOS code, based on the GEANT4 code, and this was compared with a simulation performed with PENELOPE and measured data.We believe that this underdosage does not have a significant effect on the dose received by culture cells deposited in a monolayer and adhered to the base of the wells.
Affiliation: Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete (CHUA), C/ Hnos Falcó 37, 02006 Albacete, Spain email@example.com.Show MeSH
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Mentions: Next, a radiation geometry like that used in cellular radiation was simulated, but minus the culture plate, i.e. 5 cm of water, 2 cm of air, and another 5-cm thickness of water. We compared the results of the simulation with the experimental measurements obtained in the zone of interest for us (the first water–air interface). In order to evaluate the underdosage, we compared the problem geometry ‘water–air–water’ (5 + 2 + 5 cm) to ‘all water’ geometry (a thickness of 12 cm). Experimental measurements were performed using X6MV photons from a Siemens PRIMUS linear accelerator at a dose-rate of 200 UM/min. Radiation was delivered via a single field at 180°, which went through 5 cm of water-equivalent material (Plastic Water® from CIRS, Computerized Imaging Reference System Inc., Norfolk, VA, USA). A Ross plane-parallel ionization chamber (PTW-Freiburg, Freiburg, Germany) (Fig. 3b) was used to measure the dose in the interface between water and air. These measurements were done in order to validate the simulations results. The plane-parallel chamber is the recommended chamber for measuring percentage of depth doses (PDDs) in the build-up or build-down areas . The drawback is that the chamber used has a distance of 2 mm between the electrodes. It is very important to mention that the chamber was irradiated downside. We compared the chamber response in this situation with the irradiation in the standard situation and the difference was <1%.Fig. 3.
Affiliation: Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete (CHUA), C/ Hnos Falcó 37, 02006 Albacete, Spain firstname.lastname@example.org.