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Biomedical subjects

R Adams

Publications and source records attributed to R Adams.

206 records · Page 12Linked to original sources
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Testing the count rate performance of the scintillation camera by exponential attenuation: decaying source; multiple filters.

An algorithm and two FORTRAN programs have been developed to evaluate the count rate performance of scintillation cameras from count rates reduced exponentially, either by a decaying source or by filtration. The first method is used with short-lived radionuclides such as 191mIr or 191mAu. The second implements a National Electrical Manufacturers' Association (NEMA) protocol in which the count rate from a source of 191mTc is attenuated by a varying number of copper filters stacked over it. The count rate at each data point is corrected for deadtime loss after assigning an arbitrary deadtime (tau). A second-order polynomial equation is fitted to the logarithms of net count rate values: ln(R) = A + BT + CT2 where R is the net corrected count rate (cps), and T is the elapsed time (or the filter thickness in the NEMA method). Depending on C, tau is incremented or decremented iteratively, and the count rate corrections and curve fittings are repeated until C approaches zero, indicating a correct value of the deadtime (tau). The program then plots the measured count rate versus the corrected count rate values.

Algorithms↗
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Comparison of tympanometry and otoscopy in establishing pass/fail referral criteria.

Impedance tests, pure tone screening, and pneumatic otoscopy were performed on two groups of children. For the second group, two physicians, one an otolaryngologist and the other a pediatrician, performed the otoscopic examination. Agreement between tympanometry and otoscopy was not influenced by the presence or absence of acoustic reflexes or passing or failing the pure tone screening, but did depend on the criteria used in classifying the tympanograms. Tympanograms classified as having significant negative pressure were those showing the poorest agreement between tympanometry and otoscopy. Between examiners, agreement in otoscopic findings was generally poor. Results are discussed as they apply to establishing pass/fail criteria for screening with impedance.

Auscultation↗
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An investigation of the relationship between low back pain and lumbar posteroanterior stiffness.

OBJECTIVE: To investigate the relationship between low back pain (LBP) and lumbar posteroanterior (PA) stiffness. DESIGN: A repeated-measures design was used to measure lumbar posteroanterior stiffness on two occasions in subjects with and without LBP. SUBJECTS: Twenty-five subjects with acute or subacute LBP and twenty-five pain-free subjects participated. Pain subjects reported pain on the application of a manual PA force to the lumbar spine and had no contraindication to PA stiffness testing. Pain-free subjects reported no history of LBP requiring treatment, and obtained a score of 0 on the McGill Pain Questionnaire. METHODS: PA stiffness was measured in subjects with LBP when (a) they first presented with pain and (b) when pain had resolved by more than 80%. Pain-free subjects, matched with pain subjects on gender, age, vertebral level to be tested and time between tests, were also measured on two occasions, to control for the effects of repeated stiffness testing and the passing of time. RESULTS: In subjects with low back pain stiffness decreased by 1.21 N/mm between test 1 and test 2. A paired t test found a significant difference between the tests (t = 3.04, df = 24, p = .006). In subjects without pain, there was an increase in stiffness of 0.74 N/mm between test 1 and test 2; a paired t test found no significant difference between the tests (t = -1.673, df = 24, p = .107). CONCLUSIONS: Subjects with LBP showed increased PA stiffness compared with when they had little or no pain, whereas pain-free subjects showed unchanged PA stiffness over time.

Adult↗
PubMedDate not supplied

Number of sampling movements and manual stiffness judgments.

OBJECTIVE: It has been suggested that when using posteroanterior pressure to assess the stiffness of the spine, no more than two or three oscillations should be used. This study sought to examine this clinical impression by investigating the effect of the number of sampling movements on stiffness perception. DESIGN: Perceptual study using a mechanical device to provide stiffness stimuli, with university staff and students as judges. SETTING: University psychophysics laboratory. INTERVENTIONS: In part 1, subjects were directed to sample the stimuli a prescribed number of times (either 1, 2, 3, 4 or 5 pushes), whereas in part 2, subjects were free to choose the number of sampling movements. MAIN OUTCOME MEASURE: Measures of interstimulus discriminability and bias. RESULTS: An inverted-U relationship between the number of directed sampling movements and stiffness discriminability was found, with three cycles providing best discriminability. When subjects were given a choice, most chose to use three cycles. The number of sampling movements had no effect on bias. CONCLUSION: This study confirms the hypothesis under investigation and suggests that therapists will be maximally sensitive when using three testing cycles of posteroanterior pressure to assess stiffness.

Adult↗