[Gonadal dosage in thoracic radiography. Significance of precise field blending and of the lumbar lead apron for gonadal dosage in thoracic radiography].
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PURPOSE: Assessment of the additional morbidity risk due to repeated bedside chest radiography according to ICRP 60 during intensive care. MATERIAL AND METHODS: Ventral surface doses were recorded by thermoluminescence dosimetry in 2 man and 7 women, mean age 36 +/- 12 years, mean height 169 +/- 5 cm, mean weight 74 +/- 8 kg, receiving long-term ventilation therapy due to Adult Respiratory Distress Syndrome (ARDS). RESULTS: From 18 to 126 days duration of therapy 9 patients received a total of 348 bedside chest radiographs, mean 39 +/- 22 radiographs per patient. 217 chest radiographs yielded 217 surface doses and 217 gonadal doses. Patient's mean surface dose varies between at least 0.31 +/- 0.12 mGy and at most 0.56 +/- 0.09 mGy. The surface dose representing gonadal exposure is less than 0.03 mGy per exposure. The mean effective dose is about 0.15 mSv per exposure. The cumulative effective dose Heff ranges between 2.49 mSv and 14.09 mSv, thus estimating the additional individual cancer risk ranges between 0.01% and 0.07%. CONCLUSION: In comparison with the decreased prognosis of severely ill long-term ventilated patients the additional morbidity risk due to chest radiographs is a negligible quantity.
All three currently commercially available systems for digital radiography of the chest such as the selenium drum, storage phosphor plates and the flat panel direct detector systems provide an excellent image quality that is at least equivalent or superior to that of conventional film. Reasons for that are the continuously improved detective or dose efficiency of the detector systems and an improved image processing. The new direct detector systems have the largest potential for dose reduction while storage phosphor and selenium radiographs are usually obtained with a dose comparable to that of a 400 speed system. Improved image processing algorithms allow for the production of digital images that are adapted to the conventional image characteristics within the lung regions combined with an increased transparency of the high absorption areas such as the retrocardial and retrodiaphragmatic regions.
This paper outlines how objective measurements of both image quality, in terms of signal-to-noise ratio, and effective dose may be used as tools to find the optimum kVp range for a digital chest radiography system. Measurements were made with Thoravision, an amorphous selenium-based digital chest X-ray system. The entrance surface dose and the effective dose to an anthropomorphic chest phantom were determined demonstrating how effective dose is related to beam quality. The image quality was measured using detective quantum efficiency, threshold contrast and a radiologist preference trial involving 100 patients. The results show that, despite the fact that the entrance surface dose decreases as the kVp increases, the effective dose, a better measure of the risk, reaches a minimum value between 90 and 110 kVp; however, the image quality decreases as the kVp increases. In this study the optimum kVp for chest radiography, using a selenium-based radiography system, is in the range 90-110 kVp. This is contrary to the 120- to 150-kVp range that is commonly used. Also, this study shows how objective measurements can be used to optimise radiographic technique without prolonged patient trials.
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A special technique giving good quality front and lateral chest roentgenograms in emergencies with no danger for the critically ill patient is described. The system consisted of a double-drawer plate-holder: one was passed at the back of the thorax, the other then being perpendicular to it. Placing the patient on an X-ray transparent stretcher made the technique easier. Several people were required to gently move the patient while the plate-holder was put in place.
PURPOSE: Evaluation of digitized chest x-ray for the detection of pulmonary infiltrations in bone marrow transplant patients during aplasia. METHODS: Digitized chest x-rays of 40 patients (21 female, 19 male) with "Fever of unknown origin" (FUO) were evaluated concerning radiological signs of pulmonary infiltrations and correlated to clinical findings, blood chemistry, microbiology and bronchoscopy. Additionally, an individual risk profile was established. RESULTS: In 11/40 patients pulmonary infiltrations were detected in digitized chest x-rays (group 1). 10/11 developed an infectious pulmonary infiltration. 29/40 patients developed no pulmonary infiltration (group 2). When fever increased for the first time (initial chest x-ray) a sensitivity, specificity, positive and negative predictive value of 46%, 86%, 56%, 81% and for the chest x-rays in progress of 61%, 79% 68% and 73% was found. C-reactive protein and temperature increase occurred statistically significantly earlier (p < 0.05) in group 1 compared to group 2. The average latency of digital chest x-rays in comparison to c-reactive protein and temperature increase was 6 days. The incidence of risk factors was significantly higher in group 1 in comparison to group 2 (p < 0.05). CONCLUSION: Digitized chest x-rays are not a reliable method for primary detection of pulmonary infiltrations after bone marrow transplantation. Individual risk factors have to be taken into consideration to indicate further diagnostic methods such as computed tomography at an earlier time.
PURPOSE: Determination of incidence and mortality of pulmonary pathologies arising after gastroscopy for acute bleeding, of left to right ratio of pulmonary findings in postgastroscopic chest films, and determination of a possible relationship between bleeding activity and frequency of aspiration. METHODS: 174 patients with emergency gastroscopies for upper gastrointestinal haemorrhage with pre-/postendoscopy chest films, retrospective analysis. Of the pulmonary findings, infiltrates and atelectases were considered. RESULTS: After emergency gastroscopy, 16% of patients had infiltrates or atelectases at chest radiography. Mortality within 30 days in the study group was 18%, and 39% among the subgroup with radiologically proven pulmonary complications. The distribution of chest findings between left and right side was 1:1,3. In the subgroup with gastroscopic signs of bleeding the share of postgastroscopic pulmonary findings was slightly superior to that of patients without direct signs of bleeding; however, the difference was statistically not significant. CONCLUSION: Endoscopy-related aspirations do not seem to account for an increased rate of pulmonary complications after emergency gastroscopy.