Article Figures & Data
Figures
- FIGURE 1.
Correction factor (CF) as function of volume normalized to 6 mL, determined by site 1 based on measurements obtained on 1 CRC dose calibrator. Volume dependence is 0.28%/mL.
- FIGURE 2.
Correction factor (CF) as function of volume normalized to 6 mL, determined by site 2 based on measurements obtained on 3 CRC (•) and 1 Atomlab (♦) dose calibrators. Volume dependence is 0.21%/mL and 0.16%/mL, respectively.
- FIGURE 3.
Correction factor (CF) as function of volume normalized to 6 mL, determined by site 3 based on average of measurements obtained on 3 CRC dose calibrators. Bold line (♦) represents results for sequential 1-mL volume withdrawal from 9 to 3 mL, and dashed line (•) represents results for sequential 1-mL volume addition from 3 to 9 mL. Volume dependence is 0.20%/mL and 0.11%/mL, respectively.
- FIGURE 4.
Correction factor (CF) as function of volume normalized to 6 mL, determined by sites 4 (•) and 5 (▪) based on average of measurements obtained on 3 Mark V and 15 Atomlab dose calibrators, respectively. Volume dependence is 0.12%/mL and 0.13%/mL, respectively.
Tables
Site Calibrator 90Y Activity measurement Procedure 1 5 CRC-15R 90Y in saline* Calibrated dial setting determination: Start activity and volume of 1,406 MBq (38 mCi) in 3 mL Volume dependence: Start activity and volume of 81.4 MBq (2.2 mCi) in 3 mL Sequential addition of 1 mL saline up to 9 mL 2 CRC-12, CRC-15R, 35R, and Atomlab 100 90Y in saline A. Start activity and volume of 1,184 MBq (32 mCi) in 8 mL B. Dilute with YCl3/HCl carrier to give enough volume for preparation of syringes and liquid scintillation master C. Accurately (to within 0.1%) dispense large volume master into syringes whose needles had been previously sealed to prevent leaks—total of 14 syringes prepared over the volume range, with several repeated preparations at 3, 5, 7, and 9 mL to study syringe variability and repeatability D. Prepare nominally 200-fold dilution of large volume master for liquid scintillation measurements E. Determine activity concentration of diluted solution and master by liquid scintillation counting using 2 different, independent techniques 90Y ibritumomab tiuxetan in formulation buffer Same procedure as for 90Y in saline, but large volume master is prepared with formulation buffer instead of carrier; smaller number of syringes are prepared (3, 5 [×2], 7 mL); liquid scintillation cocktails are prepared using both formulation buffer and carrier solution to study composition/stability effects 3 3 CRC-15R 90Y ibritumomab tiuxetan in formulation buffer Start activity and volume of 1,184 MBq (32 mCi) in 9 mL Sequential withdrawal of 1 mL of solution volume down to 3 mL Sequential addition of 1 mL ibritumomab tiuxetan in formulation buffer up to 9 mL 4 3 Mark V 90Y in saline Start activity and volume of 509 MBq (13.8 mCi) in 3 mL Sequential addition of 1 mL saline up to 9 mL 5 15 Atomlab† 90Y in saline‡ Start activity and volume of 481 MBq (13.0 mCi) in 3 mL Sequential addition of 1 mL saline up to 9 mL ↵* Activity for calibrated dial setting determination and volume dependence study are different because of use of different syringes.
↵† Ten new and 5 repaired units as old as 11 y; all 4 models of this type of dose calibrator use the same chamber assembly, so there is no need to distinguish between models.
↵‡ During initial volume test, on the 8 mL step, a backfill into the saline vial resulted in source material loss, but initial calibration for activity measurement was unaffected. Volume test was repeated, with a start activity of 92.5 MBq (2.5 mCi) in 3 mL. Repeated results are reported; no backfill was detected.
Site Calibrator Setting 1 5 CRC 48, 47, 50, 52, 53 2 3 CRC 58 ± 2*, 55 ± 2*, 54 ± 2* Atomlab 393 ± 6* 3 3 CRC 47, 48, 47 4 3 Mark V 897, 897, 896 5 10 New Atomlab 375, 375, 374, 375, 378, 372, 374, 376, 375, 373 5 older units after recalibration 394, 373, 363, 368, 371 Summary Atomlab mean calibrated dial setting = 375; range = 363–394 CRC mean calibrated dial setting = 51; range = 47–60 Mark V mean calibrated dial setting = 897; range = 896–897 ↵* Uncertainties on the dial settings are expanded uncertainties determined from the combined standard uncertainty on the 90Y activity calibration. The uncertainties at the other sites were not evaluated; thus, only ranges of values are given.
For the CRC dose calibrators, all dial settings are ×10; that is, the instrument readout must be multiplied by a factor of 10 to obtain the correct activity value. For the Mark V dose calibrators, all dial settings are ×100.
