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Title: Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL)

Abstract

Great variability exists in the response of urinary stones to SWL, and this is true even for stones composed of the same mineral. Efforts have been made to predict stone fragility to shock waves using computed tomography (CT) patient images, but most work to date has focused on the use of stone CT number (i.e., Hounsfield units). This is an easy number to measure on a patient stone, but its value depends on a number of factors, including the relationship of the size of the stone to me resolution (i.e., the slicewidth) of the CT scan. Studies that have shown a relationship between stone CT number and failure in SWL are reviewed, and all are shown to suffer from error due to stone size, which was not accounted for in the use of Hounsfield unit values. Preliminary data are then presented for a study of calcium oxalate monohydrate (COM) stones, in which stone structure-rather than simple CT number values-is shown to correlate with fragility to shock waves. COM stones that were observed to have structure by micro CT (e.g., voids, apatite regions, unusual shapes) broke to completion in about half the number of shock waves required for COM stones thatmore » were observed to be homogeneous in structure by CT. This result suggests another direction for the use of CT in predicting success of SWL: the use of CT to view stone structure, rather than simply measuring stone CT number. Viewing stone structure by CT requires the use of different viewing windows than those typically used for examining patient scans, but much research to date indicates that stone structure can be observed in the clinical setting. Future clinical studies will need to be done to verify the relationship between stone structure observed by CT and stone fragility in SWL.« less

Authors:
; ; ;  [1];  [2]
  1. Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202 (United States)
  2. Methodist Hospital Institute for Kidney Stone Disease, 1801 North Senate Boulevard, Suite 220, Indianapolis, Indiana 46202 (United States)
Publication Date:
OSTI Identifier:
21056958
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 900; Journal Issue: 1; Conference: 1. Annual international urolithiasis research symposium, Indianapolis, IN (United States), 2-3 Nov 2006; Other Information: DOI: 10.1063/1.2723592; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; APATITES; BIOLOGICAL EFFECTS; CALCIUM COMPOUNDS; CAT SCANNING; DISEASES; HYDRATES; IMAGES; KIDNEYS; OXALATES; RESOLUTION; SHOCK WAVES

Citation Formats

Williams, James C. Jr., Zarse, Chad A., Jackson, Molly E., McAteer, James A., and Lingeman, James E. Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL). United States: N. p., 2007. Web. doi:10.1063/1.2723592.
Williams, James C. Jr., Zarse, Chad A., Jackson, Molly E., McAteer, James A., & Lingeman, James E. Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL). United States. doi:10.1063/1.2723592.
Williams, James C. Jr., Zarse, Chad A., Jackson, Molly E., McAteer, James A., and Lingeman, James E. Thu . "Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL)". United States. doi:10.1063/1.2723592.
@article{osti_21056958,
title = {Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL)},
author = {Williams, James C. Jr. and Zarse, Chad A. and Jackson, Molly E. and McAteer, James A. and Lingeman, James E.},
abstractNote = {Great variability exists in the response of urinary stones to SWL, and this is true even for stones composed of the same mineral. Efforts have been made to predict stone fragility to shock waves using computed tomography (CT) patient images, but most work to date has focused on the use of stone CT number (i.e., Hounsfield units). This is an easy number to measure on a patient stone, but its value depends on a number of factors, including the relationship of the size of the stone to me resolution (i.e., the slicewidth) of the CT scan. Studies that have shown a relationship between stone CT number and failure in SWL are reviewed, and all are shown to suffer from error due to stone size, which was not accounted for in the use of Hounsfield unit values. Preliminary data are then presented for a study of calcium oxalate monohydrate (COM) stones, in which stone structure-rather than simple CT number values-is shown to correlate with fragility to shock waves. COM stones that were observed to have structure by micro CT (e.g., voids, apatite regions, unusual shapes) broke to completion in about half the number of shock waves required for COM stones that were observed to be homogeneous in structure by CT. This result suggests another direction for the use of CT in predicting success of SWL: the use of CT to view stone structure, rather than simply measuring stone CT number. Viewing stone structure by CT requires the use of different viewing windows than those typically used for examining patient scans, but much research to date indicates that stone structure can be observed in the clinical setting. Future clinical studies will need to be done to verify the relationship between stone structure observed by CT and stone fragility in SWL.},
doi = {10.1063/1.2723592},
journal = {AIP Conference Proceedings},
number = 1,
volume = 900,
place = {United States},
year = {Thu Apr 05 00:00:00 EDT 2007},
month = {Thu Apr 05 00:00:00 EDT 2007}
}
  • Radiation dose to the patient and personnel was determined during extracorporeal shock wave lithotripsy treatment of 60 patients. Surface radiation dose to the patient's back from the fluoroscopy unit on the side with the kidney stone averaged 10 rem (100 mSv.) per case, although the range was wide (1 to 30 rem). The surface dose from the opposing biplane x-ray unit was less, averaging 5.5 rem (55 mSv.) per case but again with a wide range (0.1 to 21 rem). Exit dose at the lower abdomen averaged 13 mrem. (0.13 mSv.) per case and estimated female gonad dose averaged 100more » mrem. (1.2 mSv.). Radiation dose to personnel working in the extracorporeal shock wave lithotripsy suite averaged less than 2 mrem. (0.02 mSv.) per case, making it a procedure that is safe in regard to radiation exposure.« less
  • Extracorporeal shock wave lithotripsy is the treatment of choice for the majority of upper urinary calculi in adults. Technical limitations, including patient size and concerns over post-treatment stone fragment passage, have made the application of extracorporeal shock wave lithotripsy in children less clearly defined. We report the successful application of the Dornier lithotriptor in the management of 18 children (22 kidneys) with upper urinary calculi.
  • The radiation techniques of different operators who performed extracorporeal shock wave lithotripsy of the kidney were evaluated retrospectively. The study was limited to 9 operators who each performed more than 100 procedures on the Dornier lithotriptor. The average fluoroscopic time and number of video spot films per procedure for all operators were 4.1 minutes and 6.5, respectively. However, the average fluoroscopic time per operator varied from 1.4 to 7.6 minutes and the average number of video spot films per operator varied from 3 to 13. The results illustrate the need for some operators to reduce fluoroscopic time and video spotmore » filming.« less
  • Extracorporeal shock wave lithotripsy is rapidly becoming an accepted treatment of renal calculi. Since fluoroscopy is involved to image the stones it is important to know how much radiation the patient receives during this procedure. Surface radiation exposure to the patient was measured in more than 300 fluoroscopic and radiographic procedures using thermoluminescent dosimeters. Initial results showed an average skin exposure of 10.1 rad per procedure for each x-ray unit, comparing favorably with exposure rates for percutaneous nephrostolithotomy and other routine radiological procedures. Factors influencing exposure levels include stone characteristics (location, size and opacity), physician experience and number of shocksmore » required. Suggestions are given that may result in a 50 per cent reduction of radiation exposure.« less
  • Sound emitted from the Dornier system GmbH lithotriptor was found to be of sufficient intensity to warrant concern about noise-induced sensorineural hearing loss. The patients were exposed to impulses of 112 dB. peak sound pressure level. Operating room personnel were exposed to sounds of less intensity, although the number of impulses they were exposed to was much greater, thereby increasing the risk of hearing loss. Hearing protection is recommended for patients and operating room personnel.