ABSTRACT
PURPOSE: Patients with hematuria and renal colic often undergo CT scanning. The purpose of our study was to assess variations in CT protocols and radiation doses for evaluation of hematuria and urinary stones in 20 countries. METHOD: The International Atomic Energy Agency (IAEA) surveyed practices in 51 hospitals from 20 countries in the European region according to the IAEA Technical cooperation classification and obtained following information for three CT protocols (urography, urinary stones, and routine abdomen-pelvis CT) for 1276 patients: patient information (weight, clinical indication), scanner information (scan vendor, scanner name, number of detector rows), scan parameters (such as number of phases, scan start and end locations, mA, kV), and radiation dose descriptors (CTDIvol, DLP). Two radiologists assessed the appropriateness of clinical indications and number of scan phases using the ESR Referral Guidelines and ACR Appropriateness Criteria. Descriptive statistics and Student's t tests were performed. RESULTS: Most institutions use 3-6 phase CT urography protocols (80 %, median DLP 1793-3618â¯mGy.cm) which were associated with 2.4-4.9-fold higher dose compared to 2-phase protocol (20 %, 740â¯mGy.cm) (pâ¯<â¯0.0001). Likewise, 52 % patients underwent 3-5 phase routine abdomen- pelvis CT (1574-2945â¯mGy.cm) as opposed to 37 % scanned with a single-phase routine CT (676â¯mGy.cm). The median DLP for urinary stones CT (516â¯mGy.cm) were significantly lower than the median DLP for the other two CT protocols (pâ¯<â¯0.0001). CONCLUSIONS: Few institutions (4/13) use low dose CT for urinary stones. There are substantial variations in CT urography and routine abdomen-pelvis CT protocols result in massive radiation doses (up to 2945-3618â¯mGy.cm).
Subject(s)
Hematuria/diagnostic imaging , Radiation Dosage , Tomography, X-Ray Computed/methods , Urinary Calculi/diagnostic imaging , Adult , Female , Humans , Male , Middle Aged , Urinary Tract/diagnostic imaging , Urography/methodsABSTRACT
The aim of this study is to investigate the possibility of replacing the standard CTA protocol for peripheral arteries with a low dose CTA protocol without affecting the diagnostic image quality. Therefore a single centre retrospective study was conducted involving 200 exams of patients undergoing lower limb angiography. All exams were performed on a 64-row detector CT and the vascular density, muscle density, noise and radiation dose of each image were assessed. The subjective image quality was evaluated additionally by an experienced radiologist. Significant differences were observed in radiation dose and image quality between the standard CTA protocol and the lower dose CTA protocol. No differences were found between objective and subjective image quality. Using 80kVp instead of 120kVp as the tube voltage for lower limb CTA reduces the radiation dose without affecting the diagnostic image quality.
Subject(s)
Computed Tomography Angiography/methods , Image Processing, Computer-Assisted/standards , Peripheral Arterial Disease/diagnostic imaging , Quality Assurance, Health Care/standards , Aged , Female , Humans , Image Processing, Computer-Assisted/methods , Male , Middle Aged , Prognosis , Radiation Dosage , Retrospective StudiesABSTRACT
Ethylenediamine (en) reacts with the polyhedral borane anion [n-B(20)H(18)](2)(-), in the presence or absence of strong nonnucleophilic auxiliary bases, to produce the [ae-B(20)H(17)(en)](3)(-) anion. In either case, substitution is accompanied, to an approximately equal extent, by reduction of the starting material to form [a(2)()-B(20)H(18)](4)(-). As found with similar substituted systems derived from this 20-boron structure, [ae-B(20)H(17)(en)](3)(-) may be conveniently rearranged to the [a(2)()-B(20)H(17)(en)](3)(-) anion. A more convenient synthesis of the known [ae-B(20)H(17)NH(3)](3)(-) ion, which employs acetonitrile as the source of the NH(3) ligand instead of liquid ammonia, is also described.