This is like a who dun it. A story about suspects in an intriguing study of the different elements that builds suspicion amongst colleagues. What lies at the centre of this set of circumstances and why is that so important? 

Since I work with radioactive substances you can imagine that here is a fair bit of regulation that goes along with it. These regulations are actually standard world wide. Producing shipping and working with these substances is fairly safe if these protocols are followed. In the morning the material is shipped and is at its highest concentration and gradually over time it decays into its sable state. Each radionuclide has its own decay scheme and particular half life. In PET 18F has a 108 minute half life or roughly two hours. In the morning we usually get two buckets with a vial with aproximately 10mL in each. The second round of doses arrives at around lunch time. The second bucket is meant to keep us going until the second shipment arrives. The stuff travels about two and a half hours from the cyclotron where it is produced. 
The vials come in a shielded container that is aproximately 15kg in total weight. Material that is dense is used as shielding as its half value layer is suitable for reducing environmental exposure to those around it. That metallic container fits snuggly in a cut out foam form specifically cut to accomodate the metal shielding. The top piece comes off to reveal the handle of the metal shield. The bucket has a lid that tightens as you screw it on and each case is then locked with a tamper seal that brake off when you need to open it. On the outside of the bucket plastic see through pockets display warning signs about the contents of the package. All of these signs have to be removed and the vial itself has to be remove as well before sending the bucket back. 

On this particular day while I was going through the procedure with a patient at around noon the second shipment came in. There was one more dose in the vial before we had to switch it to the next one. Needless to say the empty and the full bucket went back with the driver. We quickly realized the error and contacted the driver to come back. He is authorized to bring the doses to us but not to take any back. There is a lot of regulation regarding this. 

The trouble with this is that no one owned up to removing the signage and cracking the seal. To top it all off the form that accompanies the empty shipment wasn’t filled out properly. The first mistake was that both bucket numbers were filled in even though only one was opened and used. Secondly there wasn’t a clear separation between the used and unused buckets. That was what I noticed before they left as I drew doses. It was almost like a disaster waiting to happen. The person that signed for the new shipment wasn’t working with the doses and maybe wasn’t aware that the second bucket was not emptied yet. 

When asked the person who signed for the second shipment denied removing the signage from the bucket. When asked the person who opened the bucket in the morning denied removing the signage from the non empty bucket. I denied removing the signage from the bucket too. I was believed as I was busy with a patient. I knew that the I emptied bucket had some signage on it. I was going to change it after my injection and then go for lunch. 

Our suspicion rested on the person who signed for the new shipment. If they had to crack the seal and then remove the signage they should have been aware that the doses were not used. The number of the second bucket should not have been filled in. The problem is the denial. Someone has to be lying if everyone denies removing the signage and breaking the seal. Admitting mistakes is important. It says a lot about you. The person on whom the suspicion rests has had a hard time adjusting to the pace and type of work that is done here. This just adds to their reputation and their perceived honesty. 

The driver came back and I made note of all the form problems. We caught the mistake in time to mitigate it. There is a lesson here that is anecdotal and not quantifiable but qualifiable although the analysis has a binary result. This was troubling but illustrative.