The threshold energy of the Mg(p, n) Al reaction has been measured to be 5209.46+0.12 keV, using a 1 V standard as reference, and taking account of efFects due to 6nite beam energy spread, nonuniform proton energy loss in the target, and ionization of the magnesium atoms. The Q value derived for the Al beta decay then becomes 4232.17+0.12 keV, which is in clear disagreement with the most precise of the existing measurements. A further measurement is proposed.PACS number(s): 21.10. Dr, 23.40.s, 27.30.+t, 24.80.Dc

Entrance surface dose (ESD) and effective dose (E) to premature infants were estimated at three neonatal intensive care units in Kuwait for three standard X-ray examinations--abdominal, chest and skull X rays using a simple water phantom. The ESD was found to vary between 58 and 102 microGy for abdominal X rays, between 51 and 102 microGy for chest X rays and between 58 and 145 microGy for skull examinations. These doses are comparable to the entrance skin doses published elsewhere. The E-values were estimated using normalised organ dose dataset from the National Radiological Protection Board. The E-values for abdominal, chest and skull examinations were in the ranges of 30-46, 20-36 and 8-18 microSv per examination, respectively. The risk of developing childhood cancers from each of the three examinations was estimated to be in the range (9-117) x 10(-6) for infants undergoing 25 of these X-ray examinations during their stay in the NIC unit.

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Objectives: To investigate radiation exposure among the staff of departments of nuclear medicine (NM) and diagnostic radiology (DR) during 2008 and 2009 and to compare the mean doses received with the limit of 20 mSv/year of the International Commission of Radiological Protection (ICRP). Materials and Methods: The whole-body dose or effective dose, i.e. Hp(10), and the skin dose, i.e. Hp(0.07), of the staff of departments of NM and DR in Kuwait for the period of 2008 and 2009 were taken from the national thermoluminescent dosimetry database. A total of 1,780 radiation workers, grouped as NM physicians, radiologists, NM technologists, and DR technologists, from 7 departments of NM and 12 departments of DR were included. The annual average Hp(10) and Hp(0.07) were calculated for each group and comparisons were made between the groups and the years. A two-sided Mann-Whitney test was carried out, at the p = 0.05 level, to compare the means. The mean Hp(10) was compared with the limits of the ICRP. Results: Of the 16 distributions of Hp(10) and Hp(0.07), 10 were normal, with a mean annual Hp (10) in 2008 of 1.06, 1.03, 1.07, and 1.05 mSv for NM physicians, radiologists, NM technologists, and DR technologists, respectively. The corresponding Hp(0.07) values for 2008 were 1.03, 1.00, 1.05, and 1.03 mSv, respectively. Small but significant (p < 0.001) reductions in Hp(10) and Hp(0.07) were observed in 2009 for NM technologists and DR technologists. In all other cases, no significant (p > 0.072) differences were found. Conclusion: The annual average Hp(10) was well below the limit of the ICRP.

A study was conducted to investigate the effect of increasing x-ray tube voltage on patient dose and image quality during computed radiography (CR) examination of the lumbar spine. Images of a pelvis - lumbar spine phantom were obtained at three different tube voltages using two CR systems. The images were evaluated by image scores (IS) using the image quality criteria proposed by the Commission of the European Communities (CEC), by measuring the signal-to-noise ratio and the contrast-to-noise ratio. The entrance surface dose (ESD) to the phantom was also measured using ionisation chambers and the resulting gonad dose (G) and effective dose (E) were calculated. The CEC recommended tube voltages can be exceeded with CR systems for lumbar spine radiography. The ESD, G and E decreased by 25%-50% with both CR systems when tube voltage was increased. Although the decrease in IS was statistically significant (P < 0.05) the images obtained with the 3 tube voltages were diagnostically acceptable. The balance between image quality and patient dose can be optimised by using higher x-ray tube voltages for lumbar spine CR examinations.