摘要:

In kilovoltage X-ray treatment, beam shaping and shielding normal tissue are accomplished by thin sheets of lead cutout, the thickness of which is selected based upon either published data or measurements. Available broad beam attenuation (BBA) data are found to be unsatisfactory and are the subject of this investigation. BBA is defined as the ratio of intensity with (I) and without (I0) attenuating medium for a large field in a phantom. BBA = I(x,t,E)/I0(x,0,E), where x is the depth of measurement, t is the thickness of attenuator, and E is the beam energy. The depth x should be zero for kilovoltage beams and dmax for megavoltage beams. Unfortunately, x is limited by the window thickness which is the core of this study. A Farmer-type cylindrical ion chamber and three parallel plate ion chambers (Capintec, PS-033; Markus; and Holt) were used to measure BBA for kilovoltage beams from a Siemens Stabilipan unit. Results indicate that attenuation is strongly dependent on the window thickness. For the 240 kVp beam, the thickness of lead for 5% and 1% transmissions are 3.1 mm, and 5.2 mm, respectively, with the Capintec chamber. The corresponding values of lead thickness for the Markus chamber are 2.3 mm and 4.0 mm; for the Holt chamber the values are 1.1 mm and 2.2 mm; and for the cylindrical chambers the values are 1.1 mm and 2.3 mm, respectively. Similar variabilities in lead thickness with ion chambers were also noted for the other kilovoltage beams. The large differences in lead thicknesses produce enormous clinical errors, especially for shielding eye and other critical structures. For small thickness of lead (or = 0.3 mm) low atomic number medium. In such a situation, transmission measurements will be independent of the choice of an ion chamber.

DOI:10.1259/bjr.71.841.9534701

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

A new technique is described for evaluating trauma to the elbow. The modified radial head--capitellum view is an alternative radiological projection to that described by Greenspan and Norman (the radial head--capitellum view). This new projection is useful in demonstrating minimally displaced or non-displaced fractures of the radial head, capitellum and coronoid process.

DOI:10.1259/bjr.71.841.9534702

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

It has recently been observed using power Doppler that cerebral aneurysms appear to change size through the cardiac cycle. The purpose of this study was to develop a pulsatile flow model of cerebral aneurysm expansion and to investigate whether the observations of pulsation could be confirmed using the model. The model consisted of a latex bubble glued onto the side of a latex tube. A computer controlled pump was used to generate pulsatile flow. The degree of bubble expansion was adjusted by the use of flow restrictor placed in the downstream section of the flow rig. Ultrasound images were acquired using an Acuson 128 XP/10V colour flow scanner. True expansion (maximum area/minimum area) was measured from the B-scan image using a 7 MHz probe. Three observers measured expansion of the simulated aneurysm from the power Doppler images using a 2 MHz probe. Expansion measured with the power Doppler decreased as the colour gain setting increased, and decreased as the persistence increased. The true expansion of 1.43 was comparable with the colour gain set optimally for a persistence value of 3. The model allows simple investigations of the relationship between true aneurysm expansion and that measured from the power Doppler images. Colour gain and persistence settings must be standardized in clinical studies.

DOI:10.1259/bjr.71.841.9534703

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

Sarcoma of the thymus is exceedingly rare, especially in children. We report a case of thymic sarcoma in a child, including the imaging findings which have not been previously described.

DOI:10.1259/bjr.71.841.9534704

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

We report a 44-year-old male with generalized progressive scleromyxoedema treated by total skin electron beam therapy (TSEBT) which produced a marked improvement in the skin lesion. TSEBT can provide effective treatment for patients with widespread skin involvement in scleromyxoedema.

DOI:10.1259/bjr.71.841.9534705

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

A 68-year-old male with recurrence of malignant follicular carcinoma-oxyphilic cell type of the thyroid after surgery underwent whole body scintigraphy with 131I-sodium iodide and 99Tcm-tetrofosmin (Myoview). 131I scanning demonstrated local uptake most likely to be in the normal remnant, but 99Tcm-Myoview images delineated recurrence of the carcinoma in the neck, with more extensive involvement. We believe that a combination of 131I and 99Tcm-tetrofosmin imaging may be useful to assess the extent of disease in patients with recurrent Hürthle cell type carcinoma of the thyroid.

DOI:10.1259/bjr.71.841.9534706

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

Endometriosis is a relatively common condition in pre-menopausal women. Rarely, endometrial malignancy may arise in and co-exist with endometriosis. In this case report, the findings on CT and MRI which indicated this development are described. Multiple image-guided biopsies showed features consistent with endometriosis and the diagnosis was not confirmed histopathologically until formal laparotomy and open biopsy.

DOI:10.1259/bjr.71.841.9534707

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

摘要:

Ultrasound is useful in the assessment of patients with possible appendicitis. A diagnosis of appendicitis can be made in patients with persistent right lower quadrant pain when a non-compressible appendix greater than 6 mm in diameter is shown. When a normal appendix is affected by an adjacent lesion, reactive inflammation can cause secondary enlargement of the appendix. This article reviews ultrasound findings in conditions which can clinically mimic acute appendicitis. Examples of Crohn's disease, tuboovarian abscess, typhilitis, sigmoid diverticulitis, perforated sigmoid neoplasm, perforated peptic ulcer, perforated acute cholecystitis, caecal carcinoma and appendiceal tumours are included.

DOI:10.1259/bjr.71.841.9534708

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

DOI:10.1259/bjr.71.841.9534709

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY

DOI:10.1259/bjr.71.841.9534710

出版商:The British Institute of Radiology    

年代:1998

数据来源: WILEY