PubMed · 5572492
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H Eto. 1971. [Radioactive substances].. https://pubmed.ncbi.nlm.nih.gov/5572492/
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From time to time newspapers bring reports on "earth rays" and their alleged damaging effects on health. There is, however, no objective evidence which suggests the existence of earth rays. In spite of this, dowsers claim that earth rays are a main cause of disease, also in children. In this study we wanted to evaluate, using a double-blind design, the alleged effects of earth rays on young children. A total of 44 children in four nursery schools in the Bergen area were recruited. Two dowsers and one interviewer visited the homes of all the children. The dowsers evaluated the presence of earth rays over the child's bed while the parents were interviewed in an independent procedure about the child's medical history over the past 12 months. Whether or not earth rays where found over the child's bed, there where no differences in the reported health of the child with regard to upper and lower respiratory tract infections, stomach aches, allergies or sleeping habits. Parents' report on restlessness and hyperactivity were also the same. The study failed to find any health effects, adverse or not, of earth rays.
MR image nonuniformity can vary significantly with the spin-echo pulse sequence repetition time. When MR images with different nonuniformity shapes are used in a T1-calculation the resulting T1-image becomes nonuniform. As shown in this work the uniformity TR-dependence of the spin-echo pulse sequence is a critical property for T1 measurements in general and for ferrous sulfate dosimeter gel (FeGel) applications in particular. The purpose was to study the characteristics of the MR image plane nonuniformity in FeGel evaluation. This included studies of the possibility of decreasing nonuniformities by selecting uniformity optimized repetition times, studies of the transmitted and received RF-fields and studies of the effectiveness of the correction methods background subtraction and quotient correction. A pronounced MR image nonuniformity variation with repetition and T1 relaxation time was observed, and was found to originate from nonuniform RF-transmission in combination with the inherent differences in T1 relaxation for different repetition times. The T1 calculation itself, the uniformity optimized repetition times, nor none of the correction methods studied could sufficiently correct the nonuniformities observed in the T1 images. The nonuniformities were found to vary considerably less with inversion time for the inversion-recovery pulse sequence, than with repetition time for the spin-echo pulse sequence, resulting in considerably lower T1 image nonuniformity levels.