Trond Bogsrud MD
Recently updated 22.09.2012
Oslo University Hospital
- The patient must lie completely still while the images are being taken.
- A whole-body examination takes approximately 25 minutes.
- For PET, tissue absorption is displayed by positron-emitting, radiopharmaceutical preparations.
Registration of emission
- The positron is considered a positively charged electron.
- When the positron leaves the radioactive core, it will travel up to a few millimeters before it collides and fuses with an electron and is transformed into energy; this is called annihilation.
- The mass of the positron and the electron is transformed into energy in the form of two photons, each of 511 keV, which are emitted in diametrically opposing directions (180°).
- A ring detector around the patient will catch the photons.
- The two photons will encounter the ring detector at the same time (coincident detection), and because they have moved in exactly opposite directions, the detection will precisely localize the radiation focus (for example, a lymph node with tumor tissue).
- A modern PET-camera with ring detector can map the entire body in 20 minutes.
- The PET-scanners have integrated CT, so that the information from PET is accurately localized anatomically.
Examples of findings
- Anal cancer: Anal tumor and metastasis in lymph node
- Hodgkin's lymphoma (HL): HL with involvement of: soft tissue in the larynx , vertebra L4 , os pubis L and femur
- Cancer of the rectum: Adenocarsinom in rektosigmoideum liver metastases
- Intracranial tumors: Astrocytoma grade II/III, left parietal lobe high-grade glioblastoma, right frontal lobe
- Lung cancer: Lung tumor lung cancer with lymph node spread
- Sarcoma: Soft tissue sarcoma in the left thorax
- Cancer in the esophagus: Tumor in the distal esophagus
- Colon cancer: Metastasis-suspect lesion in adrenal gland
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