| Автор | J Peter Larsson |
| Автор | Jan Persliden |
| Автор | Michael Sandborg |
| Автор | Gudrun Alm Carlsson |
| Дата выпуска | 1996-11-01 |
| dc.description | Kerma - area product meters (KAP meters) are frequently used in diagnostic radiology to measure the integral of air-collision kerma over an area perpendicular to the x-ray beam. In this work, a precise method for calibrating a KAP meter to measure is described and calibration factors determined for a broad range of tube potentials (40 - 200 kV). The integral is determined using a large number of TL dosimeters spread over and outside the nominal field area defined as the area within 50% of maximum . The method is compared to a simplified calibration method which approximates the integral by multiplying the kerma in the centre of the field by the nominal field area . While the calibration factor using the precise method is independent of field area and distance from the source, that using the simplified method depends on both. This can be accounted for by field inhomogeneities caused by the heel effect, extrafocal radiation and scattered radiation from the KAP meter. The deviations between the calibration factors were as large as for collimator apertures of and distances from the source of 50 - 160 cm. The uncertainty in the calibration factor using the precise method was carefully evaluated and the expanded relative uncertainty estimated to be with a confidence level of 95%. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | Transmission ionization chambers for measurements of air collision kerma integrated over beam area. Factors limiting the accuracy of calibration |
| Тип | paper |
| DOI | 10.1088/0031-9155/41/11/010 |
| Electronic ISSN | 1361-6560 |
| Print ISSN | 0031-9155 |
| Журнал | Physics in Medicine and Biology |
| Том | 41 |
| Первая страница | 2381 |
| Последняя страница | 2398 |
| Аффилиация | J Peter Larsson; Department of Radiation Physics, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden |
| Аффилиация | Jan Persliden; Department of Radiation Physics, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden |
| Аффилиация | Michael Sandborg; Department of Radiation Physics, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden |
| Аффилиация | Gudrun Alm Carlsson; Department of Radiation Physics, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden |
| Выпуск | 11 |
