Association between distance from the radiation source and radiation exposure: A phantom-based study.

OBJECTIVES: The study evaluated the association between distance from radiation source and radiation exposure. BACKGROUND: Radiation exposure during medical procedures is associated with increased risk of cancer and other adverse effects. METHODS: An American National Standards Institute phantom was used to study the relationship between measured entrance surface exposure (MESE) and distance from the X-ray source in postero-anterior, left anterior oblique, and right anterior oblique projections. Three distance settings for table height were evaluated with "low" defined as 52 cm, "mid" 66 cm, and "high" 80 cm from the focal point of the X-ray source. Air-kerma and dose-area product measurements were recorded. Operator exposure with each of these conditions was measured, in a short operator (150 cm) as well as in a tall operator (190 cm). RESULTS: Aggregate results for the three projections were as follows. MESE (µGy/frame) significantly decreased as table-height increases (median, interquartile range, p-value) (low table-height 192.5 [122.4-201.2], mid table-height 105.8 [82.7-115.8], and high table-height 71.7 [58.4-75], p < .0005). The operator exposure (µGy/frame), significantly increased as the table-height increased (low table-height 0.0943 [0.0598-0.1157], medium table-height 0.1128 [0.0919-0.1397], and high table-height 0.158 [0.1339-0.2165], p < .0005). A shorter operator received higher radiation exposure compared to a taller operator (short operator 0.1405 [0.1155-0.1758] and tall operator 0.0995 [0.0798-0.1212], p < .0005). CONCLUSIONS: Increasing table-height is associated with a significant decrease in MESE. Operator radiation exposure increases with increasing table-height and shorter operators receive greater radiation exposure compared to taller operators.

Variability of forearm collateral circulation: An observational study of serial hand plethysmography testing.

OBJECTIVES: Evaluation of plethysmography as a reliable triage tool to access collateral circulation in the hand prior to transradial access. BACKGROUND: Hand plethysmographic testing has been used for access site triage prior to cardiac catheterization despite a lack of data supporting its result's stability. METHODS: Cohort of consecutive outpatients presenting for evaluation prior to cardiac catheterization underwent hand plethysmographic testing at the beginning of the office visit and before discharge. Demographics and clinical data was recorded. RESULTS: Hands (N = 887) in 445 patients were evaluated using the Barbeau plethysmography technique. Barbeau Test (BT) patterns A, B, C, and D were observed in 58%, 30%, 8% and 4% on initial evaluation. On preliminary evaluation, 780 (88%) hands had a "low-risk" pattern (A or B) and 107 (12%) hands had a "high-risk" pattern (C or D). Repeat evaluation performed 50 ±â€¯26 min later revealed a 'low-risk' pattern in 809 (91%) hands with 78 (9%) of hands showing a persistent "high risk" pattern. In 29 (27%) high-risk hands, spontaneous conversion to pattern B within <1 h occurred. Reverse Barbeau Test (RBT) at baseline showed pattern A, B, C and D in 95.9%, 2.8%, 1% and .4% respectively. There was no significant change in RBT upon follow-up evaluation. Strength of the radial artery pulsation was significantly associated with the pattern of RBT and the strength of ulnar pulsation was associated with the results of the BT. CONCLUSIONS: Plethysmographic testing of forearm circulation demonstrates variability over short intervals suggesting poor reliability for access site triage.