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.

This paper aims to show that the indwelling intrauterine tube (IIUT) is safe and can abolish repeated anaesthetics and large doses per fraction (Joslin et al, 1972) typical of high-dose-rate afterloading intracavitary treatment of carcinoma of the cervix. Highdose-rate schedules for Stage IB disease require as many as 12 (Liversage, 1969) to 17 (Dale, 1985) fractions for radiobiological equivalence with low-dose-rate schedules. The purpose of the IIUT is to act as a semipermanent channel for the applicator tube of the afterloading unit. We use the Gammamed II with a single high-activity 192Ir source (Busch et al, 1977), but the IIUT could probably be adapted for use with any brachytherapy machine or even manual afterloading systems.

Background The burgeoning usage and complexity of fluoroscopically guided procedures (FGPs) contribute to extended examination times and increased risk of adverse radiation effects. Diagnostic reference levels (DRLs) play a pivotal role in dose optimization. There are limited DRL data for FGPs in low- and middle-income countries (LMICs). Purpose To determine local DRLs (LDRLs) for common FGPs in the South African (SA) context and compare these with published international data. Material and Methods A three-year, retrospective study of the 15 most frequently performed FGPs at a SA institution. For each procedure, the 50th and 75th percentiles of kerma area product (KAP), reference point air kerma (Ka,r), and fluoroscopy time data were derived. Published international FGP DRL data were collated and compared with the 75th percentiles of local institutional dosage parameters. Results The commonest FGPs were aorto-bifemoral diagnostic angiography (n = 590), aorto-bifemoral interventional angiography (n = 287), nephrostomy (n = 265), and bronchial arterial embolization (BAE) (n = 208). Selective abdominal vessel interventional angiography (KAP = 170 Gy . cm2; Ka,r = 877 mGy) recorded the highest LDRL dosages; BAE was the longest procedure (LDRL = 38 min). Nephrostomies achieved the lowest LDRLs across all parameters (KAP = 10 Gy . cm2; Ka,r = 63 mGy, fluoroscopy time = 4.3 min). All Tygerberg Hospital LDRLs with comprehensive comparable data were within or below published ranges. Conclusion This study advances international radiation protection initiatives, addresses the paucity of LMIC DRL data, demonstrates broad alignment of Tygerberg Hospital FGP practice with international norms and highlights areas for optimization of institutional practice.

The present study was undertaken to evaluate the effectiveness of cyclosporine (CYA) and total body irradiation (TBI) or total lymphoid irradiation (TLI) in suppressing segmental pancreatic allograft rejection in totally pancreatectomized outbred Chacma baboons. In addition, the study includes our preliminary results with subcapsular renal autotransplantation of dispersed autologous pancreas in the primate.CYA in doses of 25-50 mg/kg per day produced a slight but significant prolongation of graft survival. There was a wide variation of daily CYA serum trough levels exhibited between primates on the same daily oral dose, and there was no clear correlation between absolute CYA serum trough levels and rejection. Although heterotopic auto-or allotransplantation of the tail of the pancreas in the baboon was capable of maintaining normoglycemia in pancreatectomized baboons until rejection of the graft, glucose intolerance, reduced K-values, and hypoinsulinemia were consistent findings during glucose tolerance tests, suggesting transplantation of an insufficient islet cell mass.Animals that received 76 rad (TBI) remained normoglycemic between 14 and 36 days with a median of 22 days, which indicated a modest but significant prolongation of graft survival. Animals treated with TLI (600 rad) sustained graft function between 7 and 31 days with a median of 17 days. The optimal regimen of irradiation in terms of cumulative dose, dose per fraction, number of fractions, and frequency of irradiation still requires refinement in this model.