Radiology, Nuclear Medicine and ImagingMedicine (miscellaneous)
Phân tích ảnh hưởng
Thông tin về tạp chí
BJR is the international research journal of the British Institute of Radiology and is the oldest scientific journal in the field of radiology and related sciences. Dating back to 1896, BJR’s history is radiology’s history, and the journal has featured some landmark papers such as the first description of CT "Computerized transverse axial tomography" by Godfrey Hounsfield in 1973. A valuable historical resource, the complete BJR archive has been digitized from 1896. BJR is an international, multi-disciplinary journal covering the clinical and technical aspects of medical imaging, radiotherapy, oncology, medical physics, radiobiology and the underpinning sciences. BJR is essential reading for radiologists, medical physicists, radiation oncologists, radiotherapists, radiographers and radiobiologists.
D. Neisius, H. U. Braedel, E. Schindler, E. Hoene, Sch. Alloussi
AbstractNine cases with histologically proven renal oncocytoma are presented. In all cases, ultrasonography gave the first indication of a tumour and intravenous urography was tumour-specific in only six, whilst angiography was so in only four of the cases with peripheral extension beyond the normal organ limits. Examination by computed tomography showed retrospectively, in the three cases with smaller oncocytomas up to 3 cm in diameter, findings that seemed promisingly characteristic: without contrast medium, the tumour appeared homogeneously hyperdense in comparison with normal renal parenchyma, but homogeneously hypodense after injection of contrast medium. One of the smaller oncocytomas, however, showed regions of heterogeneity both with aqd without contrast medium. Only one oncocytoma of 4 cm diameter presented the central stellate, low-attenuation “scar” described by Quinn et al. The angiographic criteria cited by Ambos were fulfilled in only three of the larger oncocytomas. In four of the cases, the tumour was enucleated and the organ left in situ on the basis of frozen section diagnosis. Those patients with tumours extending outside the organ or those of questionable diagnosis on frozen section were treated by nephrectomy. In one patient, the pathologist suspected metastasis from the thyroid; hemithyroidectomy confirmed on oncocytic adenoma of the left thyroid lobe.
When employing linear quadratic equations to calculate compensation for changes in overall treatment time, a potential confusion exists regarding use of the parameter commonly described as the dose equivalent of tumour repopulation. The more correct term for this factor is the biologically effective dose equivalent of tumour repopulation. The distinction between the two concepts is discussed and the potential errors arising from their confusion are illustrated by means of an example.
AbstractIt is now recognized that clonogenic tumour cells may repopulate vigorously during radiotherapy. Gaps in treatment schedules which lead to prolongation of overall treatment time may therefore cause sparing of tumour. Acute-responding normal tissues will also be spared if repopulation by surviving stem cells takes place. However, it is unlikely that stem cells in lateresponding normal tissues repopulate significantly over the time-scale of a conventional treatment regime; these tissues will therefore experience little or no sparing as a result of a gap. This poses a dilemma since tumour cell repopulation implies that an increased therapeutic effect in the post-gap phase of treatment may be necessary to compensate for any prolongation of treatment time, but it is difficult to achieve increased tumour effect without also increasing damage to late-responding normal tissues. Neither increased total dose nor increased fraction size is able to achieve this. A possible solution is provided if total treatment time can be held constant, with unchanged total dose and fraction size, by use of twice-daily conventionally sized dose fractions administered after the gap. Provided the twice-daily fractions are sufficiently spaced (not less than 6–8 h apart), the result will be to offset repopulation in tumour and acute-responding normal tissues without additional impairment of late-responding normal tissues. The feasibility of the approach depends on being able to complete treatment by the time originally intended; it is therefore more readily applicable to gaps occurring early rather than late in a treatment schedule. The strategy should be especially advantageous for tumours with rapid repopulative potential in sites where risk of damage to late-responding normal tissues imposes limitation of dose.
AbstractThere are, as yet, no standard radiobiological methods for devising compensation for unscheduled interruptions to fractionated radiotherapy. For the foreseeable future it is likely that the concept of biologically effective dose (BED) will play an important role in the intercomparison of treatment regimes, and in the examination of the options available for dealing with unscheduled treatment interruptions. However, comparison of the BEDs associated with different treatment options does not provide an intuitively obvious indication of the magnitude of any associated differences in biological effect—an important consideration in the case of those treatments which are designed to deliver near-tolerance doses. This article reviews the implications which derive from this complication, and discusses the desirable properties of possible “one-number” treatment scoring systems which could utilize the BEDs of both the tumour and the critical normal tissue. One possible form of such a scoring parameter is suggested, and applied to some clinical examples. No special “robustness” is claimed for the proposed scoring system, but the method nevertheless allows the ranking of treatment options such that the least satisfactory may be identified and rejected.