Dose calibrator

Yield. The Rb-82 content of 50 ml of eluate, decay corrected to end of elution, collected at 50 ml/min is measured in a Capintec CRC-17 dose calibrator using the potentiometer setting recommended by the manufacturer for Rb-82. While this datum is not as significant as the dynamic yield information obtained from measurement of elution profiles, it is valuable in preliminary development work and in monitoring the performance of a given unit through an extended use period. 

The calibration of the in-line detector is accomplished by comparing the end-of-elution collected dose (as measured in a dose calibrator) to the differential elution profile (as measured by the in-line detector). With data collection at 1 sec intervals, a... 

Fig. 6.10. The IAEA WHO dosimetry service to hospitals. The procedure is administratively complicated as the service is world-wide. It can be seen that parallel measurements are always performed at a PSDL and hospitals to secure traceability of dose calibration (After Svensson et al., 1996).

Dose calibrators are standard equipment in all nuclear medicine facilities. They are used to measure the dose of radioactivity of all drugs administered. Because quantitative outcomes based on administered dose are dependent on the exactness of the dose measurement, the accuracy of the dose calibrator must be ensured with routine measurements using reference standards. Quality control and calibration of the scanners must also be scheduled on a regular basis to maintain proper performance. Because a variety of 2D and 3D scanners is used, variability in performance can be a major issue [70]. 

When the radioactive canister reaches room temperature, 15-unit (emitted or exactuator) doses should be dispensed. The first five doses are considered priming doses and are to be discarded, along with the actuator mouthpiece. The remaining 10 doses are each collected into individual dose collection tubes (Fig. 1) [84] using a fresh actuator mouthpiece. The radioactivity from the single sprays can be measured directly in the dose calibrator and the drug content... 

Quality control of the labelled peptides was carried out 4 and 24 h postlabelling using C18 cartridges (SepPak and Supelco) activated with 3 mL of methanol and 3 mL of acetic acid buffer at pH5.5. After the addition of 100 gL of labelled peptide mixed with 250 gL of 50mM EDTA solution, separation of free was achieved by elution with acetic acid buffer at pH5.5. The labelled peptide was eluted with 3 mL of methanol. The activities of the eluted fractions were measured in a Capintec CRC-15 beta dose calibrator, and the labelling yield was calculated as the percentage of the activity of the methanol solution versus the total activity of both eluants. 

A solvent module (Varian model No. 5000) with a UV detector coupled to an on-line Nal(Tl) detector was used for high performance liquid chromatography (HPLC) analysis. For radioactive measurements, a dose calibrator (Capintec CRC-7, USA), a solid scintillation counter (ORTEC, USA) with a plane (7.62 cm x 7.62 cm) Nal(Tl) detector, an automatic well type gamma counter (Compac-120, Picker, USA) and a multichannel analyser coupled to a Nal(Tl) detector (7.62 cm x 7.62 cm) were used. 

All necessary accessories for PET studies, including a dose calibrator, 18F-FDG storage, a wipe test counter, a survey meter, and so on, are kept in the van. The mobile PET van moves daily to different clients sites according to the schedule made prior to the day of examination. The patient s PET study is performed and the data are processed in the van, while the interpretation can be made either at the van or at the home site of the mobile PET company. 

An accurate dose calibrator is needed to assay the dosage of a PET radiopharmaceutical for administration to humans. The dose calibrator must be calibrated for constancy, accuracy, linearity, and geometry. The readers are referred to Saha (2004) for the details of calibration of the dose calibrator. 

A single dose may be withdrawn aseptically from the multidose vial by using a suitable syringe each syringe must be measured in the dose calibrator to verify the prescribed amount of radioactivity for a patient. 

Cut the TLC plate 4.0 cm from the bottom and measure the " Tc activity of each piece in the dose calibrator. 

Transfer the top layer (saline) to another vial and measure the activities in a dose calibrator. Lipophilic Tc-MIBI is in the chloroform fraction and the contaminants are in the saline layer. 

Count the activity on each plate using a dose calibrator or a gamma counter. 

Vials A and B and the eluted cartridge are measured for Tc activity in a dose calibrator. 

Otherwise, the strip is cut into half and placed into two test tubes for measurement with a gamma scintillation counter or a dose calibrator. 

The Thiocyanate Radiolysis Dosimeter. The thiocyanate dosimeter is a reliable, accurate, and convenient means of dose calibration in pulse radiolysis experiments, when coupled with a physical dosimeter of the type described earlier. An aqueous solution of KSCN (10 mmol dm" ) is saturated with N2O. The eaq are quantitatively converted to HO within about 3 ns, as described above (reaction 29). The hydroxyl radicals then oxidize SCN", transferring the radical center to the thiocyanate radical (SCN ) (reaction 30). The SCN radical rapidly couples with a thiocyanate ion, producing (SCN)2 ", a relatively stable radical with a high molar absorptivity (reaction 31) ... 

The results of those experiments are summarized in Figure 4, which shows the number of molecules decomposed per unit energy input vs. the distance in cm. from the beam exit window. Based on a dose calibration, these figures could be recalculated so as to express the yield as a function of dose rate in the pulse at a total decomposition of 25%. It was found that the decomposition for a given dose is independent of dose rate up to ... 

Dose calibrator and gamma counter to measure radioactivity. 

The reaction mixture is incubated for 12 min, and every 2 min the tube is carefully tapped to expose the reagents to the oxidant surface. The total amount of added radioactivity [S] is measured by a dose calibrator. 

The radiolabeled protein is purified from the reaction mixture using a PD-10 desalting colurrm. The colurrm is equilibrated by 20 ml elution buffer prior to loading of the reaction mixture. The purified material is collected in 1 ml fractions, and radioactivity is measured by a dose calibrator. Labeled proteins are usually eluted after 3—4 ml, whereas the free radionuclide is eluted much later (9—12 ml). The purified radiolabeled protein is aHquoted and stored at —20 °C. A radioligand sample (10 pi) is measured using a gamma counter. 

An isotope dose calibrator is shaped as a cylinder and is often built in beneath the working area in the safety cabinet. It measures the radioactivity of a prepared dose in a vial or syringe. Each individual radionuclide can be measured accurately. Other equipment to measure radioactivity are scintillation counters (e.g. the Nal well counter) and semiconductor-based instruments (e.g. the Germanium detector). 

Fig. 15.5 Role of engine and dosing calibration in SCR system optimization...

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