Patient doses in interventional cardiology procedures in Sudan.

Radiation doses delivered to 461 patients were measured during the period of 12 months in a hospital in Khartoum, Sudan. Kerma Area Product, Cumulative Kerma and fluoroscopy time were registered during four selected procedures, namely coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA), percutaneous transvenous mitral commissurotomy (PTMC) and pacemaker. For CA, PTCA, PTMC and pacemaker the mean and median kerma area product values in gray centimeter square were found to be (20, 17.9), (56.5, 50.3), (21.6, 19.6) and (15.3, 9.6), respectively. The obtained results for mean and median cumulative kerma in milli gray were (143.7, 120.5), (418.4, 371.4), (119.8, 102) and (88.7, 59.8) as measured for CA, PTCA, PTMC and pacemaker, respectively. The mean and median total fluoroscopy time in minutes were (5.2, 3.39), (17.6, 14.8), (18, 15) and (10.2, 7.16) as registered for CA, PTCA, PTMA and pacemaker, respectively. Maximum skin dose was estimated for 13 patients during PTCA and CA procedures. Dose exceeded 2 Gy in PTCA for one patient. In comparison with the guidelines for coronary examinations suggested by SENTINEL Consortium, a higher fluoroscopy time for PTCA procedure is reported in this study. It is realised that proper selection of irradiation area, technique modes, fluoroscopy time and conducting special training on radiation protection to the operators are the main factors for potential optimisation.

Doses to patients from photoneutrons emitted in a medical linear accelerator.

This study of doses to patients from emitted photoneutrons in a medical linear accelerator (Varian 2100C) was carried out. Dose calculation was performed using Monte Carlo Geant4 code. The model was used to calculate the neutron fluence, as a function of the neutron energy inside the treatment room to estimate the effective dose to patients. The ambient dose equivalent versus field size for patients is reported in this study. The ambient dose equivalent using 1 x 1 cm(2) field size, at isocentre and X-ray modes of 20, 18, 15 and 10 MV, was found to be 1.85, 1.79, 0.61 and 0.06 mSv Gy(-1), respectively. The mean energies of emitted photoneutrons were 0.48, 0.44, 0.40 and 0.16 MeV at X-ray modes of 20, 18, 15 and 10 MV, respectively. The results of ambient dose equivalent from emitted photoneutrons cannot be ignored and can represent a risk for healthy tissues. This study emphasised that Geant4 Monte Carlo code is an appropriate choice for studying photoneutron production and transport.

Entrance surface doses to patients undergoing selected diagnostic X-ray examinations in Sudan.

The aim of the study was to evaluate the entrance surface doses (ESDs) to patients undergoing selected diagnostic X-ray examinations in major Sudanese hospitals. ESD per examination was estimated from X-ray tube output parameters in four hospitals comprising eight X-ray units and a sample of 346 radiographs. Hospital mean ESDs estimated range from 0.17 to 0.27 mGy for chest AP, 1.04-2.26 mGy for Skull AP/PA, 0.83-1.32 mGy for Skull LAT, 1.31-1.89 mGy for Pelvis AP, 1.46-3.33 mGy for Lumbar Spine AP and 2.9-9.9 mGy for Lumbar Spine LAT. With exception of chest PA examination at two hospitals, mean ESDs were found to be within the established international reference doses. The results are useful to national and professional organisations and can be used as a baseline upon which future dose measurements may be compared.

Systematics for the cross-sections of the reactions (n, p), (n, alpha) and (n, 2n) at 14.5 MeV neutrons.

Systematics are proposed for the (n, p), (n, alpha) and (n, 2n) reactions cross-sections at 14.5 MeV neutron energy based on the statistical model, with consideration of the Q-value dependence and odd-even effects. The obtained relations are compared with other recently proposed systematics based on the statistical model as well as on the asymmetry parameter dependence.