Discrepancy between C lambda and CE.

With the introduction of SI units in radiology the quantity exposure will probably be abandoned for therapy level dosemeters because of the inconvenient conversion factors which have, in SI units, to be applied for the change into absorbed dose. Instead of exposure, a quantity is envisaged which, like absorbed dose, is measured in the unit gray (= joule per kilogram). A difficulty lies in the fact that in the immediate future only primary standards of exposure will be available, necessitating the introduction of conversion factors at the interface between primary and secondary standards or field instruments. Expert opinion differs as to whether a kerma quantity, a half-way stage to the desired situation, should be used, or whether the full step should be taken involving the calibration of field instruments in terms of 'absorbed dose in water under specified conditions'. This paper discusses the problem and recommends the full step.

Radiometry↗

PubMed1978

An improved uptake probe designed for a large crystal rectilinear scanner.

Stationary probes are frequently used to estimate the uptake of radionuclides in particular organs such as the liver, spleen, heart or thyroid. Conventional probes have both a non-uniform response volume along the detector axis and a large diverging field of view. Therefore the sensitivity of these probes is strongly dependent on organ depth and the extent of the activity in the surrounding tissues. This paper describes a focused probe which can be used to give an improved response relative to organ depth and reduces the effect of the surrounding activity. Phantom measurements suggest that under suitable circumstances the probe could be used to measure absolute organ activity.

Radiometry↗