By X. Lukar. Lafayette College.
Although there is a wide selection of advanced clinical applications software order propranolol 80mg with amex, the ability to develop user defined applications buy propranolol 40 mg amex, without the need for advanced programming skills buy 40mg propranolol amex, remains a requirement that is not always available. Confirmation of results arising from application software is the responsibility of the site concerned. Particular care needs to be taken to ensure that interpretation is correct for the population concerned (e. There are many accessories for gamma cameras, including some that reduce overall reliability. One example is automated collimator exchangers that do not permit manual override and therefore result in the system being inoperable in the event of malfunction. Although basic collimators have changed very little (except for construction), there is a range of specialized collimators now available including fanbeam and cone-beam collimators that provide improved efficiency as well as marginally improved resolution compared with that of parallel hole collimators. Some manufacturers strive for ‘super- resolution’ at the expense of counting efficiency; consequently specifications should be carefully examined as collimator names can be misleading. In the case of transmission sources, there is a range of available options with no single system acknowledged as clearly superior, and effectiveness of correction is dependent to some extent on the software supplied. For example, it is now common for manufacturers to offer iterative reconstruction software as an alternative to filtered back-projection. The system choice is normally based on the underlying camera unless there is very high priority for a specific acquisition (e. The use of such an approach enables comparison of bids, resulting in a possible scoring system that will assist in the decision making process. The above tests should be done in addition to the following planar gamma camera tests. Minimum quality control requirements for gamma cameras Routine quality control is an essential requirement for any nuclear medicine practice in order to ensure that equipment operation remains optimal. Quality control is commonly, but wrongly, viewed as a difficult and time consuming chore and, for this reason, is frequently neglected. This section provides guidelines for minimum quality control based on the Australian and New Zealand Society of Nuclear Medicine recommendations and is compatible with other recommendations. The guidelines are intended to provide a very basic practical approach to gamma camera quality control, requiring very little specialized equipment or expertise. It is therefore recommended that these guidelines be adopted by all nuclear medicine practices. The minimum quality control tests are intended to detect problems before they have an impact on clinical patient studies. Further tests may be required to trace the cause of a problem and to ensure that the equipment is performing properly after service or adjustment. Exact quality control procedures vary between manufacturers and models, making it impractical to provide detailed quality control procedures covering all equipment. In order to make quality control procedures as simple as possible, the following is a suggested list of the minimum test equipment required: (a) Cobalt-57 sheet source This source is recommended for high count extrinsic uniformity checks and the collection of uniformity correction floods. It is preferable to water filled flood tanks, which may introduce non-uniformities due to poor mixing, bulging 118 4. On some systems, a water filled flood tank may also be required to calibrate the system for non-99mTc radionuclides such as 67Ga. The finest bars should be small enough to test the intrinsic resolution of the system (i. It is imperative that quality control procedures be carried out in a consistent manner (i. Proper record keeping greatly facilitates detection of gradual deterioration of performance over an extended period of time. A baseline set of quality results should be recorded after installation and acceptance testing to serve as a reference. For each quality control test listed below, the aims and rationale are described first, followed by a general procedure for performing the test. Although recommendations are made on the frequency of the quality control tests, it must be pointed out that in some tests this depends on the equipment. It is recommended that, on the basis of these guidelines, an experienced nuclear medicine physicist draw up detailed quality control protocols for use with specific equipment. In practice, the routine quality control tests should give data that permit the physician to decide whether: —To image patients normally; —To image patients but request that the equipment be serviced; —To cease patient studies until the system is repaired. Rationale and description of quality control tests: planar (a) Visual inspection A visual inspection of the collimators should be performed daily and whenever collimators are changed. Signs of new dents, scratches or stains should be followed up with a background and/or contamination check and an extrinsic uniformity check before a suspect collimator is used for patient imaging.
In those cases order propranolol american express, especially with parenteral nutrition order propranolol master card, the patient may be pre-treated with sincalide (Section 5 purchase propranolol 80 mg on line. Interference by opioids can be minimized by delaying the study for four hours after the last dose. The digital data can be reformatted to 5–15 min images for display and hard copying. Cinematic display of the data may reveal additional information not readily apparent on the film. When acute cholecystitis is suspected and the gall bladder is not seen within 40–60 min, 3–4 hour delayed images should be obtained, or morphine augmentation may be employed in lieu of delayed imaging. If the patient is being studied for a biliary leak, imaging delayed by 3– 4 hours and patient positioning manoeuvers (e. Interventions A variety of pharmacological or physiological interventions may enhance the diagnostic value of the examination. Appropriate precautions should be taken to promptly detect and treat any adverse reactions caused by these manoeuvres. This may occur in patients who have fasted longer than 24 hours, are on parenteral hyperalimentation or have a severe intercurrent illness. Sincalide should be administered slowly (over 3–5 min) to prevent biliary spasm and abdominal cramps. If the cystic duct is patent, the flow of bile into the gall bladder will be facilitated by morphine induced temporary spasm of the sphincter of Oddi. A second injection of radiopharma- ceutical (a booster dose of approximately 1 mCi) may be necessary prior to morphine injection if the remaining liver and/or biliary tree activity appears insufficient to permit gall bladder visualization. Imaging is usually continued for another 30 min following morphine administration but may be extended if desired. Contraindications to the use of morphine include respiratory depression in non-ventilated patients (absolute), morphine allergy (absolute) and acute pancreatitis (relative). Numerous protocols can be employed, but when performing and interpreting this procedure, the physician must adhere to a specific technique (i. If visual assessment of gall bladder emptying is adequate, a fatty snack may be used. Interpretation (a) Normal A normal hepatobiliary scan is characterized by immediate demon- stration of hepatic parenchyma, followed sequentially by activity in the intra- extrahepatic biliary ductal system, gall bladder and upper small bowel. Gall bladder visualization implies a patent cystic duct and excludes acute cholecystitis with a high degree of accuracy. Some renal excretion of the tracer may be seen, and bladder activity should not be regarded as pathological. A pericholecystic hepatic band of increased activity (the rim sign) is often associated with severe phlegmonous and/or gangrenous acute cholecystitis, and constitutes a surgical emergency. In chronic cholecystitis, the gall bladder will usually be seen within 30 min of morphine administration or on 3– 4 hour delayed images, while true cystic duct obstruction (acute cholecystitis) will result in persistent gall bladder non-visualization. Visualization of the gall bladder after activity in the bowel has been observed has a significant correlation with chronic cholecystitis. Severely ill patients and those on total parenteral nutrition will have a high incidence of gall bladder non-visualization even after morphine despite a patent cystic duct, and a larger dose of morphine (0. This may be seen more easily using a cinematic display and when the patient is imaged in the decubitus position. However, no evidence of hepatobiliary excretion in a jaundiced neonate having received phenobarbital is probably due to biliary atresia. Urinary excretion of the tracer (especially into a diaper) may be confused with bowel activity and is a potential source of erroneous interpretation. This abnormal bile reflux is highly correlated with bile gastritis, a cause of epigastric discomfort. Reporting In addition to patient demographics, the report should include the following information: (a) The indication for the study (e. Since activity within the lumen of the bowel can move antegrade and retrograde, frequent images will increase the accuracy of localization of the bleeding site. Clinical indications Gastrointestinal bleeding can be either upper, originating above the ligament of Treitz, or lower, distal to the ligament of Treitz. Frequent causes of upper gastrointestinal bleeding include esophageal varices, gastric and duodenal ulcers, gastritis, esophagitis, Mallory–Weiss tears or neoplasms. Causes of lower gastrointestinal haemorrhage include angiodysplasia, diver- ticula, neoplasms and inflammation, and, in children and young adults, Meckel’s diverticulum. Endoscopy and angiography provide accurate locali- zation of bleeding sites and potential therapeutic control. This is a major advantage since most gastrointestinal bleeds are intermittent and therefore are frequently missed by other methods. The clinical picture for active gastrointestinal haemorrhage is often unreliable and misleading. There is frequently a marked temporal lag between the onset of bleeding and clinical presentation.