By K. Osmund. California State University, Bakersfield.
This could lead to other discount cialis 20mg line, probably unnecessary imaging tests or even interventional procedures buy cheap cialis 20mg. Access to previous imaging is one of the most important issues to reduce unnecessary imaging due to repeated studies purchase cialis 10mg on-line. Teleradiology will be part of this effective cialis 2.5 mg, but it should be considered that especially international and/or anonymous teleradiology could be a risk for lower quality. Proper imaging is a complex procedure requiring optimal equipment and choice of optimized protocols [14]. These challenges are not so difficult to meet and easy measures, such as the use of simple lead screens, allow for sufficient protection of the personnel. Whether extra precautions will be needed for newer applications, such as breast tomosynthesis, is currently being investigated at the level of the International Electrotechnical Commission. Radiation protection in a wider sense is discussed and the focus is on the appropriate use of X rays in patients undergoing X ray imaging of the breast and populations being screened for breast cancer by means of X ray mammography. We will first explain how doses to the breast are estimated and how they are used to ensure the best compromise in image quality and detriment from X rays. Only the glandular tissue is known to be sensitive to X rays and it is, therefore, the tissue of interest in dosimetry. In addition to the impact on the difficulty in reading of the mammogram, the distribution and amount of glandular tissue will also determine the absorbed doses in the glandular tissue from a mammographic examination. The first models of the breast for dosimetric calculations used a simple approximation, with the breast being a semicylinder with a layer of skin and a homogeneous mixture of glandular tissue and fat. The relative amount of glandular tissue was then a parameter that could be varied to a value between 0 and 100%. Monte Carlo techniques were applied to estimate the dose to the glandular tissue for given situations of beam quality and compressed breast thickness of the models. There are two groups of methods being used today: Dance’s approach [1, 2] and Wu’s approach [3]. For each woman, exposure parameters along with some patient related parameters (compressed breast thickness, fraction of glandular tissue, projection view) are to be collected. A large number of data can be used to construct dose histograms for further analysis. A practical difficulty is associated with the estimation of the glandular fraction. They obtained a glandularity distribution that depends on the thickness of the compressed breast. This curve was applied in the early United Kingdom population dose studies [6] and is still applied in most dose survey studies today. An example of dose distribution using these averaged glandularity coefficients is shown in Fig. The analysis was performed separately for Europe, Asia and North America, and showed that the glandularity estimate of Dance et al. An example of how these data can be used for creating awareness is shown in Figs 2 and 3. In our local network of mammography systems, we control the mammography systems following the European Guidelines for Quality Assurance [8] and the Belgian obligations of (3 yearly) patient dosimetry. Part of a feedback document as sent to centre 78 after a dose survey in 78 centres. Centre 78 is coloured in green and can, therefore, easily be compared to all the other centres. In the case of high doses, the feedback document can motivate a centre to start dose optimization studies. In medical imaging, this translates into doses should be as low as possible, while images should be suitable for the radiological task. Breast imaging is well studied in this respect and should be considered an example for other imaging applications. In Europe, the common approach to studying the suitability for the radiological task is translated into the measurements of the threshold gold thickness of discs with a diameter of 100 µm.
The resultant lipid-laden macrophages are 34 Chapter 2: Cardiovascular system termed foam cells purchase cialis 10 mg overnight delivery, an accumulation of which causes a four patterns of plaque depending on its position and visible pale bulge called a fatty streak cheap 2.5 mg cialis with visa. This suggests that the initiation of fatty Concentric lipid rich: 28% of plaques streak may not be due to the risk factors for atheroscle- Eccentric lipid rich: 12% of plaques rosis buy cialis 2.5mg fast delivery. They contain varying amounts of free lipid buy cialis 5mg with visa, collagen tains free lipid as well as foam cells with an overlying and foam cells. A grading system exists based on (dobutamine) may show abnormal ventricular wall the level of activity provoking pain (see Table 2. Risk factor modification is crucial, in particularstoppingsmoking,treatmentofhypertension, Grade I Pain as a result of strenuous physical activity only improving diabetic control and lowering cholesterol. The figure shows a cardiac cycle from each lead taken at rest (left) and during exercise (right). Symptomatic treatment may involve one or a combi- careinconjunctionwithβ-blockersorinpatientswith nation of the following: heart failure. They are particularly useful after a my- If symptoms cannot be controlled by medication, the ocardial infarction to reduce the risk of a subsequent main choices for coronary intervention are between cardiac event. In patients with triple vessel disease or verapamil also reduce the heart rate and the force of left main stem coronary artery disease, surgery im- ventricular contraction resulting in a decreased my- proves outcome. A bal- plaques with a lipid-rich morphology are at greatest risk loon is inflated in the coronary artery to reduce the of fissuring. It includes the follow- or is provoked more easily, persists for longer and often ing: fails to respond to medical treatment. Patients require r Unstable angina describes clinical states between sta- emergency assessment and investigation to allow rapid ble angina and acute myocardial infarction. Pathophysiology As with stable angina, the underlying pathological lesion Clinical features istheatheromatousplaque. There may also be signs of r High-risk patients may benefit from a glycoprotein hypertrophy or previous infarction (Q waves). If the level is normal patients venousheparininplaceoflow-molecular-weighthep- are defined as having unstable angina. Artery occluded Pattern of infarction r 24–72 hours: Cellular inflammation visible. If the atrioventricu- Acute myocardial infarction is caused by the occlusion lar node is involved bradyarrhythmias are common, of a coronary artery, usually as the result of rupture of although any arrhythmia is possible. The myocardium supplied by that artery eas of infarction, which cause contractile dysfunction. Myocardial infarctions due to extensive myocardial damage, rupture of the occur more commonly in the early morning possibly ventricular septum or papillary muscle leading to mi- due to increased coronary artery tone, increased platelet tral regurgitation. The latter present with worsening aggregatability and decreased fibrinolytic activity. The refractory heart failure and a loud pansystolic mur- extent and distribution of the infarct is dependent on the mur. If left untreated this has a very poor prognosis, coronary artery affected, but also on individual variation and early surgical correction should be considered. A haemopericardium develops due to exsanguination into the pericardial cavity resulting in tamponade and rapid death. This Clinical features complication tends to affect older hypertensive pa- Patients typically present with central crushing chest tients, females more than males and the left ventricle pain worse than stable angina, radiating to the jaw and more than the right. It may provoke fear of imminent death over the infarction with resulting risk of embolism. It is often associated with restlessness, breath- r Recurrent ischaemia or myocardial infarction may oc- lessness, sweating, nausea and vomiting. Signs may in- cur due to thrombus formation within the same or clude pallor, sweating, hypotension, tachycardia, raised other coronary arteries.
It is characterised by impaired insulin is converted to insulin) and detection of autoan- insulin secretion and insulin resistance cialis 2.5mg lowest price. These tests are useful in distinguishing patients r Type 2 diabetes used to be called non-insulin depen- with type 1 from type 2 diabetes buy cialis 2.5 mg low price. Diabetes requires a combination of education purchase cialis 20mg otc, dietary advice cheap cialis 20 mg free shipping, insulin regimens and careful monitoring and Incidence/prevalence follow-up. Normally the liver immediately takes up 50% of Sex insulin output of the pancreas. Most patients are man- M = F aged on a twice-daily regimen or basal bolus regimen (see page 454). Geography Good control of blood glucose reduces small ves- Wide geographic variation. Trial has shown that only 12% of intensively monitored and treated patients developed retinopathy after 9 years, compared to >50% of the conventionally treated pa- Aetiology tients. Acombination of genetic and environmental factors Monitoring: both in the development of insulin resistance and im- r Regular capillary blood glucose measurement often paired insulin secretion. The overall concordance in pre-meals, two hours post meals and during the night monozygotic twins is up to 90%. Once include diet both in relation to obesity, lack of exercise a patient is stabilised on a particular regimen moni- andtheepidemiologicalevidencethatonce‘westernised’ toring may be less frequent. Loss of weight by an obese patient can lead to normal- Pathophysiology isation of blood glucose levels and resolution of symp- r Insulin resistance in the liver, skeletal muscle and adi- toms. However,thereissufficient biguanides in patients with moderate renal or hepatic insulin to suppress lipolysis and ketogenesis, so that failure. These increase Clinical features levels of plasma insulin and may result in more weight Type 2 diabetes may be diagnosed on routine blood test- gain, insulin resistance and a higher risk of compli- ing (this may follow detection of glycosuria). Symp- cations, they are often avoided in the early treatment, tomatic patients have an insidious onset of polyuria, unless symptoms are severe. Diabetes causes an in- r Thiazolidinediones (glitazones) increase peripheral creased predisposition to infections, such as abscesses, insulin sensitivity. Complications r α−glucosidaseinhibitors(acarbose)whichreducethe r Acute complications: Hyperglycaemic coma which is activity of the enzyme responsible for digesting carbo- usually hyperosmolar non-ketotic coma and com- hydrates in the intestine, thus delaying and reducing plications of therapy such as hypoglycaemia due to postprandial blood glucose peaks. Macrovascular (large vessel) disease: Atherosclerosis which leads to complications such as myocardial Secondary diabetes mellitus infarction, strokes, gangrene of the legs and mesenteric artery occlusion. Definition Chronichyperglycaemiaandothermetabolicabnormal- Investigations ities seen in diabetes mellitus due to another identifiable The diagnostic criteria are as for type 1 diabetes. Causes include chronic pancreatitis, post- duced numbers of insulin receptors due to muta- pancreatectomy, pancreatic cancer, cystic fibrosis or tions in the allele for the receptor gene. Older patients with antibodies to insulin receptors Insulin counter-regulatory hormones inhibit insulin reducing their affinity for insulin. Various insulins have been r Glucagon (glucagonoma) ‘designed’ with different pharmacokinetic effects (see r Catecholamines (phaeochromocytoma) Table 11. Drugs may inhibit insulin secretion or cause damage to r Abolus of short or immediate acting insulin given the pancreatic islets. Instead, lower amounts Long acting should be used with careful monitoring, or the patient will need to be admitted for intravenous glucose and insulin to avoid either diabetic ketoacidosis or hyperos- molar non-ketotic coma. Complications of diabetes Diabetic microvascular disease Definition Microvascular diabetic complications includes diabetic retinopathy, nephropathy and the neuropathies. Aetiology It is thought that microvascular complications are sec- ondary to the metabolic derangements of diabetes, in particular hyperglycaemia. Good glycaemic control of diabetes and control of hypertension can reduce the in- cidence of complications. This may impair the uous intravenous infusion via a tunelled line may also function of the proteins.
Clinical features Pigmentationoftheskin(duetoincreasedmelanin) cheap 5mg cialis fast delivery,dia- Age betes and hepatomegaly is the classical description of the May present at any age buy 20 mg cialis with amex. Arthritis due to calcium pyrophosphate deposi- tion may occur cialis 5 mg line, usually affecting the knees and meta- Sex carpophalangeal joints cheap cialis 10 mg free shipping. Other presenting features in- M = F clude pituitary dysfunction, cardiac enlargement and/or Aetiology failure. In Wilson’s disease the mutation is thought to affect the excretion of copper from hepatic lysosomes into the bile. Excess copper in the hepatocytes causes lipid to collect Complications in the cytoplasm. There is increasing inflammation and There is a high risk of hepatocellular carcinoma if cir- fibrosis and untreated, it progresses to cirrhosis. Clinical features Investigations Heterozygous individuals are asymptomatic and usually Diagnosed on liver biopsy. Kayser–Fleischer rings (green/brown rings around the edge of the cornea) are a late diagnostic sign, but are Management variably present. Regular venesection reduces the iron load and the risk Microscopy of cirrhosis and hepatocellular carcinoma. Other man- Excess copper can be seen in the liver using special stain- ifestations are treated symptomatically, e. Itis∼2–20 × normal, but this also occurs in chronic diabetes, testosterone for gonadal failure. Investigations Reduced serum copper and ceruloplasmin levels (not Prognosis specific and 25% of patients will have normal levels). The earlier the diagnosis and treatment, the better the Urinary copper is high and increases markedly following prognosis. If diagnosed Poor prognostic factors are co-existent biliary tract dis- and treated sufficiently early, there is some improvement ease, old age and multiple abscesses. Amoebic liver abscess Pyogenic liver abscess Definition Definition Infection of the liver by Entamoeba histolytica. The development of liver abscesses is thought to follow Aetiology/pathophysiology bacterial infection elsewhere in the body. The infection water is food borne and is most common Aetiology/pathophysiology in parts of the world with poor sanitation, e. Infectionmay reach the liver by the portal of trophozoites in the intestine, which are thought to vein from a focus of infection drained by the portal vein, invade through the mucosa gaining entry to the portal e. Infection may also result from a generalised septicaemia or direct spread from the biliary tree. Clinical features Symptoms include right upper quadrant pain, anorexia, Symptoms and signs range from mild to severe, often nausea, weight loss and night sweats. Tender hepatic en- the symptoms are less marked in elderly patients, with largement without jaundice is usual. Macroscopy/microscopy Maybesingle or multiple lesions ranging from a few Investigations millimetres to several centimetres in size. Investigations Guided aspiration and stool ova, cyst and parasite exam- Ultrasound scan is useful for screening, and pus may be ination may demonstrate the organism. Blood cultures, Management liver function tests and inflammatory markers should Treated with metronidazole. Hydatid disease Management Repeated ultrasound guided aspirations may be re- Definition quired. Extensive, difficult to approach abscesses are A tapeworm infection of the liver common in sheep rear- drained by open surgery, with soft pliable drains. Chapter 5: Disorders of the liver 213 Aetiology/pathophysiology r Hepatic adenomas are oestrogen dependent tumours In man hydatid disease is caused by one of two tape- generally only seen in women. They are strongly asso- worms Echinococcus granulosus and Echinococcus mul- ciated with the oral contraceptive pill. Clinical features The disease may be symptomless but chronic right up- Primary hepatocellular carcinoma perquadrant pain with enlargement of the liver is the common presentation. The cyst may rupture into the Definition biliary tree or peritoneal cavity and may cause an acute Also called hepatoma, this is a tumour of the liver anaphylactic reaction.