Biomedical subjects

K Faulkner

Publications and source records attributed to K Faulkner.

128 records · Page 8Linked to original sources

PubMedDate not supplied

Radiation dose and somatic risk from computed tomography.

Lithium fluoride (LiF) thermoluminescent dosimeters (TLD) have been employed to measure the radiation dose distribution within a phantom and the central axis dose in air. Results are presented for seven (four EMI CT1010, one EMI CT5005, one EMI CT7070 and one Siemens DR2) different machines. Organ doses for four different computed tomography (CT) investigations (head, lung, liver and pelvis) have been estimated from previously published tables and the central axis dose in air in 3 CT units. These estimated organ doses were used in turn to deduce the somatic and genetic risks for the four types of CT examination. These calculations indicate that for an 'average' male patient undergoing a CT examination corresponding to the average conditions encountered, the total somatic risks are 3.15 10(-4), 1.98 10(-4), 2.31 10(-4), and 1.38 10(-4) for head, lung, liver and pelvis scans, respectively. The corresponding figures for female patients are 3.39 10(-4), 3.95 10(-4), 2.73 10(-4), and 1.60 10(-4). The risk from head scanning is approximately 250 times that of a dental pantomograph. Somatic and genetic risks will be approximately twice as high for contrast examinations.

Female↗

PubMedDate not supplied

Variations in measured computed tomography number values.

Computed Tomography (CT) scans of a water phantom have been performed on a number of different CT scanners, and variations in the measured mean pixel value for a central region have been observed. In addition, a positional variation of mean CT number was noted. In particular, the head rest on an EMI CT1010 scanner had a significant effect on the pixel values. To stimulate head scanning, a phantom with a Teflon annulus surrounding a water bath was used. This annulus affected both the mean and standard deviation of the pixels in a central area of the scan. Both an mAS and beam width dependence on CT numbers was noted. The effect of calibration on the measured CT numbers for each reconstruction filter was examined on one machine. The variation of CT number with reconstruction matrix and compensation filter was also investigated. These measurements suggest caution must be exercised when interpreting actual CT number values. This will be particularly relevant when the numbers are used to differentiate between tissue types for diagnostic or therapeutic purposes.

Equipment Design↗