Evaluation of Uncertainty in Brachytherapy Dosimetry

NIST is participating in Task Group # 138 (TG-138) of the American Association of Physicists in Medicine (AAPM), AAPM Recommendations on Assessing Uncertainty of the Brachytherapy Clinical Dose Evaluation Process

The goal of TG-138 is to assess the birth-to-death process of brachytherapy source manufacture, dosimetry, calibrations, treatment planning, and clinical implementation by identifying sources of uncertainty towards quantifying realistic clinical evaluation of treatments. NIST is in a unique position to contribute to this effort by analyzing ionization chamber, source anisotropy, and x-ray spectrometry data collected on hundreds of prostate brachytherapy seeds over the past several years. Sources of uncertainty that influence the chain of traceability of the NIST primary air-kerma strength standard to the clinics via secondary calibration laboratories will be identified and quantified, including those due to batch-to-batch variability of the physical properties of seeds.