ABSTRACT
Currently there are limited diagnostic reference level (DRL) data for South African (SA) public sector cardiac fluoroscopy-guided procedures (FGPs). A 4-y retrospective study of dosimetric data on 6265 patients determined typical values (50th percentile) of dosimetric data for the seven most frequent cardiac FGPs at a SA teaching hospital. Kerma-area-product (KAP), reference point air Kerma (Ka,r) and fluoroscopy time (FT) were, respectively, calculated for coronary angiography (CA) (n = 1935; 61Gy.cm2, 624 mGy, 5 min); CA with left ventriculography (n = 1687; 85Gy.cm2, 840 mGy, 3.9 min), valve screening (n = 129; 6Gy.cm2, 164 mGy, 2.3 min), percutaneous coronary intervention (n = 1922; 145Gy.cm2, 1569 mGy, 11.9 min), pacemaker implantation (n = 432; 9Gy.cm2, 100 mGy, 6.5 min), pericardial tap (n = 115; 1.9Gy.cm2, 18 mGy, 1.5 min) and transcatheter aortic valve implantation (n = 45; 65Gy.cm2, 658 mGy, 14.1 min). This work presents the largest SA public sector cardiac FGP dosimetric data to date and provides a key resource for future work in this domain.
Subject(s)
Hospitals, Teaching , Radiography, Interventional , Fluoroscopy , Humans , Radiation Dosage , Retrospective StudiesSubject(s)
Brachytherapy/instrumentation , Uterine Cervical Neoplasms/radiotherapy , Female , HumansABSTRACT
Conversion to SI units requires that the exposure rate constant which was usually quoted in R.h-1.mCi-1.cm2 be replaced by the air kerma rate constant with units m2.Gy.Bq-1.s-1. The conversion factor is derived and air kerma rate constants for 30 radionuclides used in nuclear medicine and brachytherapy are listed. A table for calculation of air kerma rates for other radionuclides is also given. To calculate absorbed dose to tissue, the air kerma rate has to be multiplied by approximately 1.1. A dose equivalent rate constant is thus listed which allows direct calculation of dose equivalent rate to soft tissue without resorting to exposure rate constants tabulated in the special units R.m2.mCi-1.h-1 which should no longer be used.
Subject(s)
Radioisotopes , Air , Energy Transfer , International System of Units , Radiation DosageABSTRACT
The relative biological effectiveness (RBE) of 100 kV X-rays compared with cobalt-60-gamma-irradiation was determined using a cell colony assay based on the survival of Chinese hamster V-79 lung fibroblasts. The 37% dose (Do) was found to range from 1.12 to 1.47 and from 1.33 to 1.63 Gy for X-rays and 60Co-gamma-irradiation respectively. The mean RBE value calculated from the Do values was found to be 1.13 +/- 0.04. This figure compares favourably with RBE values calculated from Do values using other endpoints.
Subject(s)
Radiotherapy Dosage , Animals , Cells, Cultured/radiation effects , Cobalt Radioisotopes , Colony-Forming Units Assay , Cricetinae , Fibroblasts/radiation effects , X-RaysABSTRACT
While high-energy photon radiation in radiotherapy of deeper tissues has a skin-sparing effect, contamination with electron and low-energy photon radiation can diminish and even abolish this effect. Experiments with perspex, aluminium and copper filters showed that a copper filter effectively diminished the skin dose owing to contaminated radiation.
