Factors affecting the diagnostic quality of bitewing radiographs: a review

The bitewing radiograph (BWR) has been used in dental practice for over 90 years and is a widely used technique. This paper outlines the ideal technique for producing reproducible BWR of good diagnostic quality. In particular, it reviews the technical errors that may occur while exposing and processing BWR and the psychological errors that may result when radiographs are viewed. The consequences of these errors, (unnecessary patient exposure to radiation, poor diagnosis and potentially inappropriate treatment) are outlined in detail. Steps to improve the quality of BWR and decrease patient exposure to radiation are given in line with recent recommendations.     

Day time wheel running activity in laboratory rats following geomagnetic event of 5-6 July 1974

The Nationwide Evaluation of X-ray Trends (NEXT) program has obtained data from various states on the physical factors related to patient radiation exposure from several common radiographs. Data from two years were examined for exposure, beam area/film area and exposure area product delivered to a "standard patient." The data were examined for differences as a function of operator training.     

Hodgkin''s disease in the thyroid gland

Gaining a sufficient exposure for aortic valve surgery after previous coronary artery bypass grafting (CABG) has been a problem due to the patent saphenous vein grafts. Although a patient had had CABG twice we performed aortic valve replacement (AVR) with almost the usual exposure. We attached the proximal anastomosis in a more distal position of the ascending aorta than usual, at the first CABG, as he was diagnosed to have mild aortic valve stenosis prior to surgery. We consider this method allows easier AVR after previous CABG when the patient is diagnosed with mild aortic valve stenosis before CABG.     

Reversal by desferrioxamine of tau protein aggregates following two days of treatment in aluminum-induced neurofibrillary degeneration in rabbit: implications for clinical trials in Alzheimer''s disease

Concern about possible transmission of bloodborne pathogens during medical procedures is growing among patients and healthcare workers alike. This fear has primarily been focused on nosocomial transmission of human immunodeficiency virus (HIV), but other bloodborne infectious agents may also be transmitted during procedures. Chief among these are the hepatitis viruses, particularly hepatitis B virus (HBV) and hepatitis C virus (HCV), both of which are significantly more widespread than HIV. Although radiology is not traditionally thought of as a field with significant risk for exposure to or transmission of pathogens, the expanding role of interventional procedures in recent years belies that perception. The potential for exposure to blood or other possibly infectious material exists in virtually any invasive radiological procedure, from arteriography to image-guided biopsy. Fortunately, the risk of such exposure is low, and the risk of actual transmission of a bloodborne pathogen, whether from patient to healthcare worker or vice versa, is even lower. Nevertheless, it is important for all radiologists who perform invasive procedures to be aware of these risks and to observe pertinent safety and infection control recommendations. This article will review these topics.     

Chronic hypersensitivity pneumonitis due to isocyanate in a patient presenting with acute symptoms 1 month after environmental exposure

A 51-year-old man who had been working for 10 years with polyurethane paint containing isocyanate (MDI) was admitted to our hospital with complaints of fever and exertional dyspnea. Fine crackles were heard in both bases, and the patient had clubbed fingers. A chest X-ray film and computed tomograms of the lungs revealed patchy infiltrative shadows in both lung fields and subpleural honeycombing associated with irregular linear areas. Examination of bronchoalveolar lavage fluid showed increased T lymphocytes and a decreased CD 4/8 ratio. Specimens obtained by transbronchial lung biopsy revealed lymphoplasmacytic infiltration into the thickened alveolar walls, macrophage accumulation, and micro-epithelioid cell granulomas in the alveolar sacs. Hypersensitivity pneumonitis was suspected although the causative antigen was not identified because the results of short-term environmental provocation tests were negative in the patient's home and workplace. After discharge, the patient continued working as a paint sprayer. His acute symptoms recurred 1 month after exposure to isocyanate. Similar episodes occurred on two separate occasions. In addition, the patient tested positive for antibody to MDI-HSA in bronchoalveolar fluid. From the above observations, the patient was given a diagnosis of chronic hypersensitivity pneumonitis due to isocyanate (MDI). This condition is extremely rare. Furthermore, it is interesting that acute symptoms recurred 1 month after environmental exposure to the causative antigen.     

Chronic beryllium disease: uncommon disease, less common diagnosis

Chronic beryllium disease (CBD) is typically considered only when occupational exposure to beryllium is a certainty; however, CBD has also occurred in occupational and environmental settings where exposure was unexpected. When the etiology of a case of granulomatous pulmonary disease is not determined, sarcoidosis is the "diagnosis of exclusion." This diagnosis does not communicate much information about the patient's prognosis, the disease's etiology, or even what disease etiologies were specifically excluded. Some cases of CBD have been called sarcoidosis, allowing exposure to continue for the patient and (at times) other individuals. The granulomatous changes of sarcoidosis are thought to result from an abnormal immune response. While the etiologic agents that can initiate this response are largely unknown, the immunopathogenesis of CBD has been well described, and laboratory methods are available in a few centers that can (if used) identify beryllium hypersensitivity. The potential for exposure and disease to be widely separated in time and location makes it important for health-care and environmental health professionals to be aware of these new diagnostic methods.     

Effects of x-ray tube-voltage ripple and current mode on patient dose

This paper proposes a radiographic sensitivity attenuation curve for screen-films systems. This curve expresses the relative inverse value of mAs value needed to give the same photographic density. This curve decreases more slowly with increasing object thickness than the exposure attenuation curve generally used hitherto. By using the radiographic sensitivity attenuation curve and the exposure attenuation curve, the voltage-ripple dependence of mAs values and patient dose for the same photographic density was obtained. As predicted theoretically in a previous paper [Med. Phys. 18, 921 (1991)], it was verified quantitatively the reverse order that larger ripple values resulted in lower patient dose and lower mAs value for the unsaturating current mode at large ripple. This reverse order clearly appeared in two-pulse units. These phenomena were experimentally verified. As a result it was found that in radiographing with a two-pulse unit, larger mA value results in lower patient dose.     

Review of applying implant-magnetic attachments to oral and maxillofacial prostheses]

The Postanesthesia Care Unit (PACU) is an area of high risk for the transmission of Mycobacterium tuberculosis. The Centers for Disease Control (CDC) have recommended administrative controls, engineering controls, and personal protection devices to reduce the risks; nevertheless, perianesthesia nurses inhale airborne pathogens. The CDC guidelines are enforced by the Occupational Safety and Health Administration (OSHA). If an exposure occurs, the health-care facility has an OSHA-mandated course of action. The cost of follow-up of exposed persons can be high, depending on the patient census of the PACU at the time of unprotected exposure. This report presents the CDC guidelines for follow-up of exposure and costs based on typical surgical volumes and admission patterns for a large hospital with 10 thousand or more annual surgical procedures.     

Evolutionary anomalies among the aminoacyl-tRNA synthetases

This study demonstrates that acute mainstream cigarette smoke exposure is deleterious to dorsal random-pattern skin flap survival in the rat. Three vasodilators were also studied for their ability to mediate flap survival after smoke exposure. Sprague-Dawley rats (10 per group) were exposed to two cigarettes per day over a 14-day period. This is an exposure equivalent to that of an average cigarette smoker. Dorsal McFarlane caudally based random-pattern skin flaps (4 x 10 cm) were created on day 7 of the smoke exposure. Enteral phenoxybenzamine (0.56 mg per kilogram per day), enteral nifedipine (10 mg per kilogram per day), and topical nitroglycerin (1.3 cm or 7.5 mg per day) were administered after creation of the dorsal skin flaps in two doses daily during smoke exposure. Fluorescein was used to delineate areas of viability accurately. A pad digitizer was utilized to calculate designated skin flap areas to +/-1.0 mm2. Experimental animals demonstrated a 23% decrease (p < 0.01) in skin flap area survival compared with the control animals. The phenoxybenzamine group demonstrated a 5.5% increase in flap area survival (p=0.068), the nifedipine group demonstrated a 4.1% increase in flap area survival (p=0.049), and the nitroglycerin group demonstrated an 8.9% increase in flap area survival (p=0.049). These data suggest that phenoxybenzamine appears to affect skin flap survival marginally after smoke exposure. However, nifedipine and nitroglycerin improve random-pattern skin flap survival significantly after mainstream cigarette smoke exposure in the rat. These results imply that pharmacological intervention with vasodilators may ultimately prove clinically useful for random-pattern skin flap salvage in the cigarette-smoking patient.     

Association between somatic symptoms and 24-hour ambulatory blood pressure levels

A wide variety of irritants can lead to respiratory failure after inhalation injuries. We present a case of adult respiratory distress syndrome after exposure to a fluorocarbon resin (PFF 1020) used as ski wax. The patient sustained a mild but prolonged exposure to this substance, which subsequently led to symptoms of severe respiratory failure over the next 24 hours. Except for hypocalcemia, there were no systemic manifestations and recovery was uneventful. Ski wax is considered to be nontoxic and there are no reported side effects of these products. Injury was related to the heated fluorocarbon particles. This case report of a severe lung inhalation injury points out the increasing risk of environmental hazards associated with the use of synthetic substances.     

The technical design and performance of ultrafast computed tomography

The ultrafast radiograph CT scanner utilizes a scanning electron beam and semicircular tungsten targets to produce a moving radiograph source about the patient, thus eliminating mechanical motion within the gantry. This design allows scan times as short as 50 or 100 ms, as well as two levels of image resolution. The short scan time reduces the effects of motion blurring and artifacts and provides the ability to obtain high-quality images of dynamic processes and rapidly moving organs. When utilized in the SS (high-resolution) mode, the UFCT scanner provides contiguous image acquisition through a patient volume at rapid speeds, yet maintains image quality comparable with conventional CT scanners. This technology provides extremely short exposure times, rapid acquisition of multiple slices, continuous scanning without concern for anode heat storage and dissipation, and the ability to image moving organs or flowing contrast media. Many clinical applications exist that exploit these unique features.     

Effect of in vivo exposure to iodine-131 on the frequency and persistence of micronuclei in human lymphocytes

The validity of the micronucleus test as a biomarker of chromosome damage in dividing mammalian cells is well established. This assay was used to study the response of peripheral lymphocytes of a 34-yr-old male patient following treatment with 131I ablative radiation therapy following a total thyroidectomy. Coincidentally, 8 mo before diagnosis, the patient had provided a blood sample for an in vitro study of micronucleus induction following exposure to graded doses of x-rays. The background frequency in the unexposed culture showed a mean count of 6.0 micronuclei per 1000 binucleated (first division) lymphocytes, while mean values of 18.5, 29.0, 41.0, 61.0 and 75.5 micronuclei/1000 cells were observed following x-ray doses of 5, 10, 15, 20, and 25 cGy, respectively. These data fit a nonthreshold, linear dose-response function (y = 2.78x + 3.71; r = .99). Eight months after the in vitro x-ray study, the subject was diagnosed with thyroid cancer. Surgery was performed, and 5 wk later the patient received 1.78 GBq (48 mCi) of 131I as adjuvant radiation therapy. Blood was drawn 11 d after the radiation treatment and at monthly intervals thereafter to analyze the frequency and persistence of micronuclei. The first posttreatment sample showed 35.5 micronuclei per 1000 binucleate cells. Based on the linear dose-response equation from the earlier study, the sixfold increase in micronucleus frequency suggests a dose to the peripheral blood of approximately 11 cGy. The cytogenetic dose estimate compares to approximately 30 cGy using a new model based on external whole-body counting data. Nine consecutive monthly samples have been analyzed to date. Although the micronucleus count has fluctuated (four- to sixfold above background), the frequency after 8 mo is equivalent to the first posttreatment sample. Data show that radiation-induced cellular lesions persist for months following relatively brief radiation exposure to a medical isotope. Results of this study support the conclusion that the lymphocyte micronucleus test is a rapid, sensitive, and perhaps quantitative biomarker of low-dose (< 25 cGy) radiation exposure.     

Increase in non-specific bronchial hyperresponsiveness without specific response to isocyanate in isocyanate-induced asthma: a pilot study

Increased non-specific bronchial hyperresponsiveness (BHR) has been reported after positive reaction to isocyanates in patients with isocyanate-sensitive asthma. The increased responsiveness may, however, also precede the asthma attack. We therefore compared non-specific BHR to a cholinergic agent before and after exposure to toluene-diisocyanate (TDI) that induced no asthma symptoms in 11 workers with isocyanate-related asthma. Patients were exposed for 3 consecutive days to progressively increasing doses of TDI (5, 10, and 20 ppb min-1 for 20 min) in an exposure chamber with continuous TDI monitoring. No immediate nor late asthmatic bronchial reaction was observed in any patient after any dose of TDI during or after challenge. A significant increase in non-specific BHR was noted 24 h after the last dose of TDI challenge, however. This increase was at least one doubling dose for seven of 11 patients. In conclusion, our study shows that, in patients with isocyanate-induced asthma, exposure to TDI induces a slight but significant increase in non-specific BHR in the absence of any immediate or late bronchial response to isocyanate. This result, which requires further confirmation, may justify a proposal to measure non-specific BHR, even after a negative specific inhalation test to TDI, as an additional diagnostic element for TDI-induced occupational asthma, to help lower the percentage of the undetected occupational asthma cases.     

Fate of occupational asthma. A follow-up study of patients with occupational asthma due to Western Red Cedar (Thuja plicata)

Thirty-eight patients with red cedar asthma proved by inhalation provocation test were studied after they had left exposure for more than 6 months. Twenty-seven patients became asymptomatic, with normal lung function (group A). Three patients had persistent chronic bronchitis with a moderate degree of airway obstruction, probably as a result of cigarette smoking (group B1). Eight patients continued to have recurrent attacks of asthma that decreased in severity after cessation of exposure, and their symptoms were probably due to previous exposure (group B2). The effect of breathing helium on maximal expiratory flow at 50 per cent of the vital capacity was studied. All except one patient in group A were responders (change in maximal expiratory flow at 50 per cent of vital capacity greater than 30 per cent). Two patients in group B1 and 2 in group B2 were nonresponders, suggesting obstruction in the small airways. All patients with red cedar asthma demonstrated bronchial hyperreactivity to methacholine to the same extent as patients with nonoccupational asthma. This hyperreactivity persisted after they left exposure, irrespective of symptoms. It is not known at present whether bronchial hyperreactivity is the predisposing factor in occupational asthma or is the result of the disease.     

A patient with parkinsonism presenting hyperintensity in the globus pallidus on T1-weighted MR images: the correlation with manganese poisoning

We report a 55-year-old woman who developed symptoms resembling parkinsonism. Her psychiatric symptoms in the early stage, cervical dystonia and tremor increasing on movement were consistent with manganese poisoning. Manganese levels were elevated to 1.5 micrograms/l in the serum (normal; 0.3-1.1 micrograms/l) and to 1.4 micrograms/l in the urine (normal; less than 1.2 micrograms/l). Intravenous infusion of calcium disodium editate (CaEDTA; chelating agent) was followed by the marked excretion of manganese (27.3 micrograms/l) in the urine. These findings support manganese poisoning. Manganese poisoning is a disease which results from chronic exposure to manganese, but the source of manganese exposure remained obscure in this patient. T1-weighted MRI of the brain showed symmetric high signal intensity in the globus pallidus without any abnormality on T2-weighted images. There is a report that manganese induced brain lesions in Macaca fascicularis as revealed by MRI and the fascicularis developed signs of unsteady gait and hypoactivity. The patient responded to treatment with CaEDTA and the second MRI demonstrated regression of abnormal signal intensity. This may be due to enhanced manganese excretion. To our knowledge, this is the first case of probable manganese-induced human parkinsonism whom changes in MRI were noted after treatment with CaEDTA.     

Endotracheal suctioning: a literature review

Endotracheal suctioning (ETS) is a necessary practice carried out in intensive care units. In involves the removal of pulmonary secretions from a patient with an artificial airway in place. All intensive care nurses should be aware when performing this intervention of the potential hazards a patient is exposed to, and should endeavour to prevent or minimize these. This literature review explores the criteria available to indicate a need for ETS and discusses the potential adverse effects of ETS and how these can be avoided during the procedure. The question is raised as to the frequency with which the procedure should be performed. The current dilemma facing nurses is the overwhelming view that ETS should be performed only when indicated as necessary by assessment, to minimize the exposure of the patient to the hazards of ETS, but also recognition that ETS is a necessary procedure to maintain a patent airway and clear secretions. As nurses are accountable for all aspects of their practice, they need to be able to make an informed choice about the frequency with which ETS is performed. It is hoped that this review will increase nurses' awareness of the potential hazards surrounding ETS, and enable them to question their practices regarding their ability to assess individual patient needs and determine the frequency with which ETS should be performed.     

When amnesic patients perform well on recognition memory tests.

Extended exposure to study material can markedly improve subsequent recognition memory performance in amnesic patients, even the densely amnesic patient H.M. To understand this phenomenon, the severely amnesic patient E.P., 3 other amnesic patients, and controls studied pictorial material and then were given either a yes–no (Experiment 1) or a 2-alternative, forced-choice (Experiment 2) recognition test. The amnesic patients and controls benefited substantially from extended exposure, but patient E.P. consistently performed at chance. Furthermore, confidence ratings corresponded to recognition accuracy. The results do not support the idea that the benefit of extended study time is due to some kind of familiarity process made available through nondeclarative memory. It is likely that amnesic patients benefit from extended study time to the extent that they have residual capacity for declarative memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exposure influences expressive timing judgments in music.

This study is concerned with the question whether, and to what extent, listeners' previous exposure to music in everyday life, and expertise as a result of formal musical training, play a role in making expressive timing judgments in music. This was investigated by using a Web-based listening experiment in which listeners with a wide range of musical backgrounds were asked to compare 2 recordings of the same composition (15 pairs, grouped in 3 musical genres), 1 of which was tempo-transformed (manipulating the expressive timing). The results show that expressive timing judgments are not so much influenced by expertise levels, as is suggested by the expertise hypothesis, but by exposure to a certain musical idiom, as is suggested by the exposure hypothesis. As such, the current study provides evidence for the idea that some musical capabilities are acquired through mere exposure to music, and that these abilities are more likely enhanced by active listening (exposure) than by formal musical training (expertise). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A quantitative definition of exposure and related concepts

This paper develops a unified theoretical framework for understanding exposure to environmental pollutants and other agents. It reviews the scientific literature to describe the many diverse and often confusing ways in which the term "exposure" is being used. Using six criteria proposed for a useful framework, a set of quantitative definitions, which encompass and expand upon existing definitions, is developed. After "agent" (e.g., a pollutant) and "target" (e.g., a person's hand) are defined, "exposure" is defined as the contact between an agent and a target. An "instantaneous point exposure" is defined as the joint occurrence of two events: 1) point i of a target is located at (xi, yi, zi) at time t, and 2) an agent of concentration Ci is present at location (xi, yi, zi) at time t. It is shown that the definition of instantaneous point exposure is fundamental in that all other functions of exposure with respect to space or time-such as the average exposure and the integrated exposure-can be derived from it. Because exposure and dose are closely related and often confused, our framework also includes a general definition of dose that is consistent with common usage. Finally, the definitions in this unified theoretical framework are shown to apply to inhalation exposure, dermal exposure, and ingestion exposure. In addition to the literature review and the quantitative definitions of exposure, this paper includes a glossary of terms that are proposed to help establish a common language for the exposure sciences.     

Low-dose spiral computed tomography for measuring abdominal fat volume and distribution in a clinical setting

OBJECTIVES: Computed tomography (CT) has been used to measure body composition, however, a technique with reduced radiation exposure has not yet been introduced. This study tested a low-dose spiral CT technique on a phantom to determine its validity and reproducibility. The method was then applied for volume and distribution measurements in patients. DESIGN: Construction and measurement of a phantom followed by measurement of patients referred to CT for clinical indications. SETTING: Radiology Department, University Hospital. SUBJECTS: Twenty-four post-gastrectomy patients. INTERVENTION: A 22 cm phantom with a known amount of water and fat was scanned using high- and low-dose technique, standard and double table speed during a volumetric scan. The low-dose technique was implemented in the patient group. Total volume, total fat and four defined compartmental fat volumes in the truncal area were measured. RESULTS: The mean fat volume measured using the low-dose CT technique in the phantom was 0.2% above the actual fat content. The coefficient of variation for this method was 5%. By using low-dose, double speed instead of standard-dose technique, radiation exposure to the skin was decreased by more than 90% (equivalent to 4 mGy) of what is used in diagnostic imaging. The patient scans showed that no significant differences in BMI and total measured volume existed between female and male patients, but percent fat and percent subcutaneous fat were significantly larger in women (P = 0.006 and 0.002, respectively), as were percent intraabdominal and mediastinal fat in men (P = 0.002 and 0.003 respectively). CONCLUSIONS: Low-dose spiral CT accurately measures fat volume in vitro, and can be used in vivo for compartmental fat measurements.