A gamma probe is a handheld device used with a Geiger-Muller tube or scintillation counter, for intraoperative use following interstitial injection of a radionuclide, to locate regional lymph nodes by their radioactivity. It is used primarily for sentinel lymph node mapping and parathyroid surgery. The Gamma Probe is also used for RSL (Radioactive Seed Localization), to locate small and non-palpable breast lesions.
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History
The sentinel node market experienced high growth in the early and mid 90's starting with melanoma sentinel node surgical search and breast cancer sentinel node staging; both are currently considered standards of care. Most surgeons propose node staging after a positive breast biopsy. New applications are being developed for parathyroid direct detection and intra-operative detection of cancerous tissue using tumor-seeking radiopharmaceuticals. Parathyroid detection is growing fast, while the intraoperative use of gamma probes for direct tumor detection is just emerging.
Quality Criteria
To evaluate the quality of a gamma probe system one must measure or discuss the following parameters:
- Spatial selectivity
- Spatial resolution
- Maximum sensitivity
- Quality of shielding
- Energy resolution and spectral discrimination
- Display of signal
Competition
The following companies manufacture gamma probes:
Isotopes for clinical use with Gamma Probes
- Tc99m - Technetium-99m
- I125 - Iodine 125
- I131 - Iodine 131
- In111 - Indium 111
- F18 - Fluorine 18
- Ga68 - Gallium 68
Calibration / Test Isotopes used with Gamma Probes
- Co57 - Cobalt 57
- Na22 - Sodium 22