Renewing the radiopharmaceutical accuracy check service for Canadian radionuclide calibrators

Technical Note: Minimizing geometrical uncertainties of cylindrical well‐type ionization chamber measurements: There is an optimal chamber length

“…6 lead to an optimal chamber length of~10.9 cm [10.90 cm with Eq. (12). Figure 6, furthermore, contains markers for a typical 5 ml syringe filled to 2 ml (green ⊕ symbol) and a 10 ml syringe filled to 4 ml with radioisotope (red ⊛ symbol).…”

“…It was shown that uncertainties stemming from these sources depend on ionization chamber height and can be significantly reduced by prudent design of the ionization chamber, namely adhering to the constraint expressed by Eq. (12). The magnitude of uncertainties in insertion depth relative to those in source length influence optimal ionization chamber height h and its importance increases with increasing source length l. These results apply to any ionization chamber of this kind and can be used to either optimize source insertion depth and/or source length for a given chamber design or to optimize the design length of such a chamber when nominal values of source insertion depth and length are prescribed, such as in the case of reference chambers used as instruments to transfer radioisotope calibration from a standards laboratory to radionuclide calibrators used in nuclear medicine clinics.…”

“…Because of the short half‐life (minutes to a few days) of the isotopes commonly used in nuclear medicine, accurate calibration of radionuclide calibrators is problematic owing to the shipping time involved in exchanging standard sources. Different approaches have previously been suggested to solve this problem, such as long‐lived surrogate sources or dedicated transfer instruments …”

“…Different approaches have previously been suggested to solve this problem, such as long-lived surrogate sources 10 or dedicated transfer instruments. [11][12][13] One type of transfer instrument is a precisely specified well-type ionization chamber which consists of a central well with a diameter chosen to allow insertion of a specific syringe type (e.g., 3 ml nominal volume) with a snug fit between syringe and chamber wall to maximize geometric efficiency and minimize lateral (side to side) "wiggle room". 13 A prototype design of such a chamber has an inner and outer diameter and a height of 13, 41, and 110 mm, respectively.…”

Data reconciliation connected to guard bands to set specification limits related to risk assessment for radiopharmaceutical activity

“…Since it is a procedure that involves measurements and their associated decision limits, the development of techniques and applications of various statistical tools has been used by several authors to minimize the errors that may eventually occur [ [32] , [33] , [34] , [35] , [36] , [37] , [38] ].…”