Data are presented for the first use of novel DNA-barcoded aerosol test particles that have been developed to track the fate of airborne contaminants in populated environments. Until DNATrax (DNA Tagged Reagents for Aerosol eXperiments) particles were developed, there was no way to rapidly validate air transport models with realistic particles in the respirable range of 1-10 mm in diameter. The DNATrax particles, developed at Lawrence Livermore National Laboratory (LLNL) and tested with the assistance of the Pentagon Force Protection Agency, are the first safe and effective materials for aerosol transport studies that are identified by DNA molecules. The use of unique synthetic DNA barcodes overcomes the challenges of discerning the test material from pre-existing environmental or background contaminants (either naturally occurring or previously released). The DNATrax particle properties are demonstrated to have appropriate size range (approximately 1-4.5 mm in diameter) to accurately simulate bacterial spore transport. Here, we describe details of the first field test of the DNATrax aerosol test particles in a large indoor facility.

Robustness analysis is a critical part of plan evaluation when comparing IMRT plans with spot scanned proton therapy plans.

The European Radiation Dosimetry Group (EURADOS), in collaboration with Lawrence Livermore National Laboratory's (LLNL's) Thyroid Intercomparison Program (TRIP), conducted an intercomparison exercise consistent with the goals of EURADOS. In total, 35 in vivo radiobioassay facilities from 18 countries participated to evaluate the differences between the neck and thyroid phantoms specified in two standards issued by the American National Standards Institute. Radioiodine (125I and 131I) measurement results were compared to the traceable standard activity levels added to each phantom. Measurement data showed no statistically significant differences between normalized activity measurements of the thyroid phantom types (20 and 30 ml). Differences were noted between the laboratories that routinely participate in the radioiodine thyroid intercomparison program (TRIP participants) and laboratories that have not previously participated in TRIP. Evaluation of the reasons for these differences will require additional EURADOS-LLNL collaborations. Finally, the measurement data from this intercomparison was used with a designed intake scenario for intercomparison of dose evaluations. Results from the dose intercomparison will be presented in a subsequent article.

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