Browsing by Author "Nielsen, Cybil"

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    A Comparison of the Sensitivity and Specificity of I-123 Whole body scan and Serum Thyroglobulin for Follow-up Thyroid Cancer Patients
    (Office of the Vice Chancellor for Research, 2016-04-08) Almomen, Fatimah F.; Nielsen, Cybil; Clifft, Monica; Thomas, Pamala
    Abstract Does the I-123 WBS have more sensitivity and specificity than Tg level test in follow-up for thyroid cancer? A comparison of the sensitivity & specificity between I-123 whole body scan (I-123 WBS) and serum thyroglobulin (Tg) for follow-up patients who were treated with I-131 for thyroid cancer was conducted. Methods & material: The design of this study is Null hypothesis: I-123 WBS has equal sensitivity or greater than Tg test when predicting recurrence of thyroid cancer. Alternate hypothesis: I-123 WBS has less sensitivity than Tg test. The population of this study is a convenience sample consisted of 28 patients who met the following criteria: 1) had follicular or papillary thyroid cancer or both, 2) between the period 2013 to 2015, and 3) had serum Tg results and had undergone I-123 WBS after one year of iodine therapy. Any detectable Tg value was considered positive. Tg and I-123 WBS results were compared with the final impression, which was the radiologist determination from the patient history and other tests (besides Tg and I-123 WBS), We compared Sensitivity and Specificity for both tests Results: Tg had a higher sensitivity than I-123 WBS. Tg has 75% sensitivity while I-123 WBS has 73.3 % sensitivity. I-123 WBS had a specificity of 100% and Tg had a specificity of 91.7%. Positive predictive Value (PPV) for Tg was 92.3%. and I-123 WBS was 100%. Negative Predictive Value (NPV) for Tg was 73.3% and I-123 WBS was 75%. Conclusions: I-123 WBS should not be replaced by Tg. I-123 WBS has higher specificity.
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    The Effects on Technologist Occupational Exposure in PET/CT Departments When Working with Students at Various Levels of Supervision
    (SNM, 2020-09) Farkas, Jacob; Martin, Michael; Nielsen, Cybil; Jennings, S. Gregory; Radiology and Imaging Sciences, School of Medicine
    The purpose of this study was to evaluate the effect that the presence of a student in the PET/CT department has on the technologist’s occupational radiation exposure and whether this effect is influenced by the type of supervision performed. Methods: This was a retrospective, institutional review board–approved study that collected data from 2 PET/CT departments. Dosimetry reports, correlated with the clinical schedules of the students, were normalized for workflow (amount of radioactivity), the number of technologists, and the number of monitored days in the department. A 2-sample t test assuming unequal variance with an α of 0.05 was used to compare doses between with-student and without-student groups and between direct-supervision and indirect-supervision groups. Results: The study consisted of a dataset of 42 dosimetry reports, 19 with students and 23 without students. When comparing with-student and without-student groups, the total (n = 42) extremity dose had a P value of 0.012 with a mean of 0.0011665 μSv/MBq/technologist/d; all other dose comparisons between groups were greater than 0.05 (P > 0.05). For indirect supervision (n = 21), the extremity-dose P value was 0.298. The other dose P values were all less than 0.05. For direct supervision (n = 21), the dose P values were all greater than 0.05. There was a trend toward decreasing exposure of technologists when students were in the department. Conclusion: Extremity dose decreases when students are present. There is a trend toward decreasing dose with indirect supervision.