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A new Diamentor for measuring kerma‐area product and air‐kerma simultaneously
Author(s) -
Gfirtner Hans,
Stieve FriedrichErnst,
Wild Johannes
Publication year - 1997
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598109
Subject(s) - kerma , calibration , field size , dosimetry , field (mathematics) , nuclear medicine , physics , environmental science , nuclear engineering , optics , mathematics , statistics , engineering , medicine , pure mathematics
The new M4KDK Diamentor (PTW‐Freiburg) for measuring the air‐kerma‐area product (KAP) and air kerma (AK) simultaneously was evaluated. The special design of the Diamentor chamber influences the variation of the calibration factor with respect to the field size somewhat differently to what is the case with the classic Diamentor. It is therefore recommended that calibration be performed for a larger field size. If the M4KDK Diamentor is calibrated for a field size of 3.8 cm × 3.8 cm (at the chamber), an uncertainty in the KAP value of better than 15% for all field sizes used in practice, and an uncertainty in the AK value of better than 15% for a field size larger than the calibration field, can be expected. The influence of backscattered radiation on the calibration factor is equivalent to that for the classic Diamentor chamber. The variation in response in accordance with tube potential, is also comparable with that of the classic Diamentor. Dramatic changes in response have to be expected if additional filters are introduced in close proximity to the Diamentor chamber.