Breast cancer SLN
Isotope · Tc-99m-nanocolloid / Tc-99m-tilmanocept (~37–74 MBq, peri-areolar or peritumoural)
Probe choice · CdTe 11 mm straight (SOE 3212) or 14 mm collimated (SOE 3213-AC)
In-theatre issue · Peri-areolar injection-site hot spot dominates the count rate close to the SLN basin. The collimated 14 mm CdTe probe is the directional discriminator — counts drop off sharply outside the collimator acceptance angle.
Workflow · Inject in NM the morning of surgery → lymphoscintigraphy → mark the axillary station on the skin → in OR, identify the hottest node, excise, recount the excision bed, recount the specimen ex-vivo. Repeat for every node within 10 % of the hottest node's count rate per ASCO guidance.
Melanoma SLN
Isotope · Tc-99m-nanocolloid (~10–40 MBq, intradermal at the primary site)
Probe choice · CdTe 11 mm straight (SOE 3212) for axillary / inguinal basins; CdTe 6 mm for head-and-neck close-quarters
In-theatre issue · Multi-basin drainage (axillary + inguinal + popliteal + intransit) is common — the probe needs to cover several anatomical fields per case. The 6 mm CdTe variant earns its place in head-and-neck where the smaller geometry fits the floor-of-mouth and submandibular regions.
Workflow · Pre-op lymphoscintigraphy maps every basin → in OR the probe finds each marked hot spot → excise the SLN, recount the bed and the ex-vivo specimen. Document the count rate ratio (SLN : background) as the procedural quality metric.
Gynaecological SLN (cervix, endometrium, vulva)
Isotope · Tc-99m-nanocolloid (cervical or paracervical injection)
Probe choice · CdTe laparoscopic frontal (SOE 3215) for robotic / laparoscopic pelvic SLN; lateral (SOE 3215-L) for obturator station; 45° (SOE 3215-45) for the external iliac chain
In-theatre issue · The pelvic SLN basin is reached through standard 12 mm trocars in a robotic or laparoscopic case. Frontal-tip geometry works for the axillary obturator / external iliac stations; lateral-tip for tighter pelvic-sidewall approaches. The 45° probe fills the geometry gap when neither frontal nor lateral lines up with the trocar axis.
Workflow · GROINSS-V (vulva), SENTI-ENDO (endometrium) and ESGO cervical-SLN guidance frame the technique. Inject the morning of surgery, dock the robot or set up the laparoscope, sweep the pelvic sidewall, identify the hot node, dissect and excise.
Parathyroid surgery
Isotope · Tc-99m-MIBI (~740 MBq, IV, 90 min pre-op)
Probe choice · CdTe collimated 11 mm (SOE 3211-AC) or 14 mm (SOE 3213-AC)
In-theatre issue · Pre-op SPECT-CT may be equivocal in re-operative cases or ectopic adenomas. The collimated CdTe probe at 140 keV gives directional read-out against the thyroid bed background activity.
Workflow · Inject ~90 min pre-op so the parathyroid : thyroid ratio peaks intraoperatively. Probe-sweep the neck through the standard transverse cervical incision; the hottest focus is the adenoma; excise and confirm with a 50 % drop in intraoperative PTH.
Recurrent / metastatic thyroid carcinoma (I-131)
Isotope · I-131 (364 keV) — typically post-diagnostic-scan; surgical timing depends on the protocol
Probe choice · CsI(Tl) 16 mm (SOE 3222) or collimated variant
In-theatre issue · I-131 at 364 keV is outside the CdTe optimum (20–170 keV) — this is where the CsI(Tl) family pays its way. The 100 keV – 1 MeV range covers the I-131 photopeak with sensitivity > 800 Cps/MBq.
Workflow · Confirm the I-131 uptake on the diagnostic scan; identify the surgical target (cervical-nodal recurrence, residual thyroid bed). In OR the CsI(Tl) probe localises the active focus; excise, recount the bed and the specimen.
Radio-guided occult-lesion localisation (ROLL)
Isotope · I-125 seed (27 keV) — image-guided implant 0–7 days pre-op
Probe choice · CdTe — low-energy optimum at 27 keV; standard sensitivity ample for the implant activity
In-theatre issue · I-125 ROLL replaces the wire-localisation technique for non-palpable breast lesions and selected soft-tissue masses. The advantage over wire is that the seed cannot dislodge between image-guided implant and surgical excision.
Workflow · Image-guided seed implant in radiology → surgery scheduled within the seed half-life window (≤ 1 week typical) → in OR the probe localises the seed → excise the surrounding tissue → confirm seed retrieval on the specimen X-ray and gamma count.
