摘要:

In common with other radiations the actual distribution of dose produced in a patient by high energy electron irradiation is strongly dependent on the composition of the body in the path of the beam. A system in use for the modification of unit density isodose distributions is briefly described. Since the absorption of electrons is determined by quite different processes from those applicable to X rays this system was based on the specific characteristics of electron absorption. Correction in this system starts with the representation of an isodose distribution by several depth dose distributions along axes emanating from a virtual source. Segments of these unit density depth dose distributions are translated sequentially by amounts dependent on the location, extent, and electron density of the inhomogeneous region. The various steps in this system have been briefly presented and lead to the corrected dose in and beyond a region of lower density, such as lung, and correct for the effects of both attenuation and scatter. In the case of limited regions of higher density and higher atomic number, such as bone, this method provides for the systematic correction of the dose beyond the inhomogeneity. The enhancement of dose in bone with electrons is rarely large enough to be clinically significant and is separately computed on the basis of experimental measurements made with different amounts of bone equivalent material. The differences between the corrected actual distribution of dose in the patient and that indicated by uncorrected unit density distributions are so significant that such corrections would appear to be essential if the physical advantages of high energy radiation therapy are to be realised in practice.

DOI:10.1259/0007-1285-38-446-143

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

In oestrone-pretreated rats the administration of posterior pituitary extract (Piton) evokes renal cortical necrosis. As the changes are attributed to hypoxia the authors assumed that renal vasospasm is responsible for the renal impairment.In order to confirm this hypothesis the renal vessels of living rats pretreated with oestrone were studied with angiorenographic methods after Piton injection.The studies gave direct evidence that in oestrone-pretreated rats, following Piton administration, considerable renal vasospasm, localised on the larger renal vessels, developed.Two conclusions can be drawn from the present studies.(1) Oestrone sensitises the renal vessels to the vasoconstrictive effect of posterior pituitary extract (Piton).(2) The renal cortical necrosis observed following pretreatment with oestrone and subsequent Piton administration, is the consequence of renal vasospasm. As a result of the prolonged vasoconstriction the kidney becomes hypoxic and tubular necrosis ensues.

DOI:10.1259/0007-1285-38-446-148

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

The third Postgraduate Seminar sponsored by the Department of Radiology of the University of Miami School of Medicine and Jackson Memorial Hospital is to be held on March 17–20, 1965, and is entitledGastrointestinal Roentgenology.Programmes and all necessary information may be obtained on application to Professor Raymond E. Parks, Department of Radiology, Jackson Memorial Hospital, Miami, Florida 33136, U.S.A.

DOI:10.1259/0007-1285-38-446-151

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

The meningeal arterial anastomoses are believed to be of limited importance in the normal circulatory balance (Vander Eecken and Adams, 1953), and this remains true while the pressure inside the larger arterial vessels which they connect is roughly equal (Rosegay and Welch, 1954; Symon, Ishikawa and Meyer, 1963).It cannot, however, be excluded that they will participate even under normal conditions in the blood supply to the demarcation areas between different arterial territories.Their patency (depending on their anatomic order, on the systemic arterial tension, on the possible presence of vascular lesions, etc.) largely influences the clinico-anatomical features of the cerebro-vascular disorders (Cobb, 1931).

DOI:10.1259/0007-1285-38-446-152

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

It is with great regret that we record the death of Dr. R. F. Sethna, Emeritus Professor of Radiology, Grant Medical College, Bombay, and Fellow of the Indian Academy of Medical Sciences, on November 9, 1964. He had been a member of the British Institute of Radiology since 1929.

DOI:10.1259/0007-1285-38-446-153-a

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

Though it may be unnecessary to attempt to record routinely the radiation exposure in every radiodiagnostic examination it may be desirable from time to time to estimate the exposure in a particular procedure or patient. This may be done by calibrating the output of the X-ray unit and by knowing the field irradiated and the spatial relationships of any particular organ of interest. The results may be expressed as an internal exposure in röntgens × cm2or as an integral dose in gram/rads either to the field irradiated or to a particular organ: this latter requires a knowledge of the depth dose characteristics of the X-ray beam in tissue.

DOI:10.1259/0007-1285-38-446-154

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

Treatment planning for moving field therapy using X and γ rays has been greatly simplified by the use of the tissue-air ratio, sometimes designated the tumour-air ratio (Johns, Whitmore, Watson, and Umberg, 1953; Johns, 1961). The tissue-air ratio, TAR, is defined (Brit. J. Radiol., Suppl. 10, 1961) as the ratio of the dose (or dose-rate) at a point in tissue to the dose (or dose-rate) at the same spatial point in air, where both measurements are made under conditions of electronic equilibrium. However, the ICRU has recently recommended (Report lOd, 1963, p. 8) that calibrations be made at a standard point in a phantom rather than in air. Such phantom measurements are less likely to be influenced by electron contamination or by soft radiation from collimating systems and are particularly relevant to megavoltage radiations where exposure measurements are invalid. Meredith (1963) has shown that a phantom calibration procedure can improve the accuracy of dosimetry at therapeutically important depths, particularly for lower energy radiations.

DOI:10.1259/0007-1285-38-446-158

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

Supplementary to the paper “Osteosclerosis in myelomatosis” I wish to refer to some earlier descriptions of osteosclerosis in cases of myelomatosis. The authors (Fairley, Jackson and McDonald, 1964) are misled to suppose that there were no descriptions of osteosclerotic lesions in myelomatosis before 1959 (Odelberg-Johnson). the following may illustrate this:(1) Krainin, P., d'Angii, C. J., and Gmelin, A., 1949,Arch, intern. Med., 84, 976.

DOI:10.1259/0007-1285-38-446-159-a

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY

摘要:

Communications should ordinarily be addressed to the Honorary Editors, The British Journal of Radiology, 23 Welbeck Street, London, W.1.Communications from overseas should preferably be submitted to the most appropriate of the following Associate Editors:Dr. A. C. Begg, Public Hospital, Dunedin, New Zealand.Professor H. E. Johns, The Ontario Cancer Institute, 500 Sherbourne Street, Toronto, Ontario, Canada.Dr. H. A. Luke, The Alfred Hospital, Prahran, S.1, Victoria, Australia.

DOI:10.1259/0007-1285-38-446-160

出版商:The British Institute of Radiology    

年代:1965

数据来源: WILEY