4010
This machine drift , which was not associated with a rise in water phantom temperature and did not consistently correlate with estimated x - ray tube heat , could result in a significant overestimation of regional cerebral blood flow ( rCBF ) for a xenon / CT rCBF protocol involving 5 - 7 sequential scans obtained at 1 - min interscan intervals .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
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