Patient Pathway

Thought I'd give an overview of the patient pathway to PET / CT
Before the scan
PET / CT is not typically part of first line diagnostic imaging. Typically patients will already have had plain film, CT and a biopsy. Some patients will have had or be having chemotherapy. There is no waiting list to speak of with the scan being conducted within a few days of the request, for patient convenience and transport arrangements. Many patients will have travelled a considerable distance to get to the facility.
Prep
The patient is fasted for 6 hrs before the scan so the FDG glucose analogue is taken up by the body.
Clerking
The scan is explained to the patient and detailed medical history taken. This is very relevant to the scan results and helpful to the reporting radiologist. For instance a recent injury or biopsy could lead to FDG uptake in that area.
Cannulation
The patient is has a three way cannula inserted and blood taken for a glucose check. If the glucose level is over 10 mm/ml the FDG will not be taken up by the bodies tissues and the scan must be delayed until it falls.
Radiopharmaceutical
The FDG is drawn up in the lab and the activity checked. Typically this will be 380 - 400MBq in a 0.5 to 2ml injection. The quantity injected varies because the activity level falls over time, the half life being only 2 hours. The FDG is injected via the cannula with the syringe and injection site being flushed with 15 to 20ml of saline (hence the 3 way cannula). The cannula is removed. No medication or contrast is given.
Resting
Each patient has their own small waiting room with an examination couch and chair. They rest quietly for one hour, magazines and a radio are provided. Once the patient is injected they are radioactive and it is explained beforehand that the staff need to keep a distance. The patients are in a room on their own, with a call button and are monitored with CCTV.
Scanning
Just prior to the scan the patient empties their bladder and removes jewellery or garments containing metal, a gown is offered. The patient lies supine on the examination table and enters the scanner head first. Other than the patient being straight and having their arms loosely above their head there is no special positioning requirement. The time the radiographer spends helping the patient onto the couch and positioning them is minimal. Usually directions are given from several steps back and the patient is encouraged to get on the examination table without direct assistance (to minimise staff radiation dose). The radiographer then steps up to the patient checks the head is straight in the foam support, positions a knee support, puts a blanket on the patient, reminds them to keep still and leaves.
Protocol
With the patient's details already on the system a CT Tomogram maps the patients position and length (required to plan how many beds are needed for the PET scan). The CT scan, low dose, takes 30 seconds. CT scans are head first with the patient going in and out of the scanner twice (for Tomo and CT scan). The PET scan is from thighs up (or feet if it is a total body scan). The patient is advanced through the scanner then comes back through feet first. A typical scan takes 35 minutes and is whole body (mid thigh to vertex). Each bed (or section and there are usually 8 in total) takes 3 to 5 minutes. The patient moves through the scanner advancing by one bed length at time. PET bed length is how the body is spilt up into overlapping sections of about 30cm for scanning. A very tall patient might be measured at 9 bed lengths and child might be 7 bed lengths. The patient is monitored through a small thick lead glass window, though I've read lead glass is not very effective for 511Kev gamma rays and some centres use CCTV.
After scanning
The blanket and knee support are removed and the patient encouraged to get off the table safely. Once again this is done from a distance, (it feels so weird to stand back). The patient is directed to the changing facilities and reminded to eat and drink normally, when results are to be expected and being radioactive to keep a distance from pregnant women and small children for 6 hours. If transport was organised it is usually chased at this point.
Processing
Once aquired the images are processed and the CT / PET fused. Copies are made to CD.
Reporting
The images are reported by radiologists within 48 hrs, often on the day of scanning or the following morning. Recent CT and MRI scans and reports are also viewed. The reporting is painstaking and takes at least half an hour per patient (with some taking longer). The PET is viewed first for an overall assessment. The CT is viewed axially moving from vertex down and fusing the image with PET to examine any unusual appearances. NB viewing the CT as a moving image was challenging but I found it very helpful for anatomy revision.