[en] Uncertainty provides opportunities for differences in perception, and radiation risks at low level of exposures involved in few computed tomography scans fall in this category. While there is good agreement among national and international organisations on risk probability of cancer, risk perception has barely been dealt with by these organisations. Risk perception is commonly defined as the subjective judgment that people make about the characteristics and severity of a risk. Severity and latency are important factors in perception. There is a need to connect all these. Leaving risk perception purely as a subjective judgement provides opportunities for people to amplifying risk. The author postulates a risk perception index as severity divided by latency that becomes determining factor for risk perception. It is hoped that this index will bring rationality in risk perception. (authors)

[en] Some publications have shown that Hp(_0.07) or even Hp(₁₀) can be used as good operational quantities for X-rays in view of difficulties with Hp(₃). With increasing awareness, there is tendency to use whatever dosimeter is available with correction factor to estimate eye lens dose. The best position for an eye lens dosimeter has been reported to be at the side of the head nearest to the radiation source, close to the eye. Recent studies have reported eye doses with cone beam CT (CBCT) both for patients and staff, and there are many papers reporting eye lens doses to staff in nuclear medicine. To minimise the dose to eyes, the user can take advantage of a feature of CBCT of projections acquired over an angular span of 1808 plus cone angle of the X-ray tube and with tube under scan arcs. (authors)

[en] The increasing interest in the use of Tc-99m-labeled red blood cells encourages exploration into the site and mechanism of binding of Tc-99m to the RBC components. The components isolated from the labeled red cells were the lipid and protein of the membrane, heme, and the α and β chains of the globin. The binding occurs mainly to the protein moiety, and preferentially to the β chain of the globin, where the specific activity was found to be 28 +- 6 times that of the α chain. The mechanism of binding is discussed. The role of heme in the binding is not clear

[en] Radiation protection in medicine is becoming more and more important with increasing wider use of X-rays, documentation of effects besides the potential for long-term carcinogenic effects. With computed tomography (CT) likely to become sub-mSv in coming years, positron emission tomography (PET), single photon emission computed tomography (SPECT) and some of the nuclear medical examination will become focus of attraction as high-dose examinations, even though they are less-frequent ones. Clarity will be needed on radiation effects at levels of radiation doses encountered in a couple of CT scans and if effects are really cumulative. There is challenge to develop radiation metrics that can be used as easily as units of temperature and length and avoidance of multiple meaning of a single dose metric. Other challenges include development of biological indicators of radiation dose, transition from dose to a representative phantom to dose to individual patient, system for tracking of radiation exposure history of patient, avoidance of radiation-induced skin injury in patients and radiation cataract in staff, cutting down inappropriate referrals for radiological examinations, confidence building in patient and patient safety in radiotherapy. (authors)

No abstract available

[en] During the 100 years since the discovery of x-rays, the x-ray tube has undergone significant improvements to meet the demand of shorter exposure time and frequent exposures as in angiography. This has been achieved by multiple focal spots, rotating anodes, design consideration of the anode and the tube assembly. While physical improvements have resulted in improved performance, the principle has remained the same, as also has the problem of massive heat generation which consumes almost 99% of the energy. This article traces the history of tubes and current perspectives. (author). 3 refs., 3 figs., 2 tabs

[en] The use of radiological investigations is an accepted part of medical practice, but there is no known safe radiation dose. Some spontaneous genetic mutations and some malignant diseases are attributable to background radiation. In diagnostic radiology, chest examinations are the most common at all levels, chest fluoroscopy is infrequently done at level I (4% of total), as against 39% at level II. The frequency of CT examinations is 4% of the total at level I and 0.3% at level II. In the case of diagnostic nuclear medicine investigations, the major differences between level I and the other levels are the high frequency for cardiovascular examinations at level I and thyroid uptakes at the other levels

[en] Because of mechanical displacements of certain components in the treatment head of the linear accelerator during transportation of the equipment, certain unusual corrective procedures were required for getting acceptable beam characteristics. Experiences in handling certain problems in checking of mechanical isocentre, field flatness and symmetry, optical checks for coincidence of light and radiation field are described. (author)

[en] The distribution kinetics of the ³H-labelled p-phenylene diamine (a hair dye compound), was studied when administered iv and when applied percutaneously. The tracer experiments in rabbits after iv administration showed a biphasic blood clearance with half life values of 24 min and 43.5 h and quick-percutaneous absorption. The tissue distribution pattern investigated after iv and percutaneous administration in 16 different tissues and also in blood did not demonstrate any target organ for selective localisation of the dye. Not more than 0.06 percent of the iv administered radioactivity was measured per 10 mg of any tissue at 12th day. (author)

[en] The hepatobiliary imaging has been used for study of gallbladder and cystic duct disorders but its utility in evaluating dynamics of flow through common bile duct has not been explored. The pattern of curves over CBD and liver in patients with or without patent cystic duct has been studied. Normally the CBD curve shows a steady rise till peak (in 13.7 ± 3.6 min) in ^99mTc-EHIDA study followed by the steady fall. The time to peak for CBD curve, transit time from liver to CBD and the pattern of falling portion of the curve provide information about biliary dyskinesia. Moreover, comparison of the rate of fall of the liver curve with pattern of CBD curve further gives diagnostic information about dynamics in CBD. (author)