Erratum: New National Air-Kerma-Strength Standards for (125)I and (103)Pd Brachytherapy Seeds.

[This corrects the article on p. 337 in vol. 108.

New National Air-Kerma-Strength Standards for (125)I and (103)Pd Brachytherapy Seeds.

The new U.S. measurement standard for the air-kerma strength from low-energy photon-emitting brachytherapy seed sources is formally described in detail.

The Graphite Calorimeter as a Standard of Absorbed Dose for Cobalt-60 Gamma Radiation.

Absorbed dose to water in a cobalt-60 gamma-ray beam has been determined using a thick-walled graphite ionization chamber. The chamber was calibrated in a graphite phantom against a graphite calorimeter, and the graphite calibration factor was converted to a water calibration factor using published energy absorption coefficient ratios and a measured replacement factor. Comparisons between the graphite and water measurements were made at pairs of points that were scaled in position according to the ratio of electron densities, so that the photon spectra were the same for the two points in a given pair.