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Flex Probe CXS-OP-SZF


The articulatable hand-held probe FlexProbe® is the smart answer to the question of whether a straight or an angled probe is more suitable for the localization of sentinel lymph nodes in Breast Cancer, Melanoma, Prostate Cancer or other cancers.

Our FlexProbe® combines both options in one probe.

Flex probeFrom the straight position the 3 cm long head of this probe is rotatable by 30 degrees. So even under difficult geometrical conditions it's possible to locate lymph nodes (for example: the lymph node is behind non-removable tissue). The FlexProbe® uses the same collimator sleeves as the Straight-probe CXS-OP-SZBN which have dihedral angles (FOV) of 40° (standard), 15°, 20°, 60°, 90° and 120°.

In combination with the standard collimator sleeve (40°) the FlexProbe® has a very high sensitivity (> 20,000 counts/s/MBq), excellent side shielding (99.97%) and optimal spatial resolution (< 17 mm) at a probe tip diameter of 15 mm.
The FlexProbe® was designed for the radiation energy of the most used nuclide 99mTc (140 keV) and has optimal parameters for it.

The side shield is made by tungsten collimators, which are integrated in the stainless steel probe tube. The detectable energy range is from 70 keV (201Tl) up to 511keV (PET nuclide). The FlexProbe® can not be used with the optional PET collimator sleeves. The collimators are built into stainless steel tubes that can be unscrewed and steam sterilized separately.

When used intra-operatively the probe has to be protected by a sterile latex cover. As, for example, those used in ultrasound diagnostics.

Technical Data

Detector CsI:Tl-scintillation crystal Ø 6 mm x 8 mm long, read out by a 20 mm2 pin-photodiode
Gamma-energy Range 60 keV … > 511 keV
Probe Properties Length: 210 mm;
Length of cable: 3 m
Diameter hand piece: 20 mm
Diameter of tip: 15 mm
Weight: about 7 ounce (200 g)
Special Features 6 different collimator sleeves available

Collimation and Side Shielding

Material Tungsten, lateral thickness 3.15 mm (at all collimator sleeves with D = 15 mm), rear thickness 5 mm
Side shielding = 99.97 % @ 140 keV (99mTc)
Dihedral angle (FOV) Standard 40° FWHM, changeable by 6 different collimator sleeves

Background Sensitivity

Zero effect < 0.3 cps = 18 c/min


The sensitivity of the probe depends on the used collimator. The basic sensitivity is determined by the standard collimator (40°). The sensitivity is shown in the figure - it's depending on the distance between lymph-node and probe tip. The probe FlexProbe® has a high sensitivity > 20,000 counts/s/MBq.

Angular Resolution

The angular resolution with a standard collimator (40°) is determined in the near field (distance: 3 cm) and in the far field (distance: 10 cm).

Spatial Resolution

The spatial resolution with a standard collimator (40°) is determined in the near field (distance: 1 cm). The probe has an excellent spatial resolution < 17 mm.

Spatial Resolution and Sensitivity at Different Measuring Conditions

Spatial resolution, angular resolution and sensitivity depend strongly on the actual measurement conditions and from the selected collimator geometry.

The spatial resolution and sensitivity of different collimators were determined in a water phantom.

(Distance Tip-Source: 30 mm)Dihedral Angle Colllimator Angle
40° 90° 120°
Local Resolution in Air mm 23 40 46
Local Resolution in Water mm 24 40 47
Sensitivity in Air Counts/MBq 690 1360 1538
Sensitivity in Water Counts/MBq 585 1120 1154

By increasing the dihedral angle the sensitivity increases significantly, while the spatial resolution gets worse.

Due to the very good side shielding and good spectral energy resolution of our probes the spatial resolution and sensitivity in water (phantom) is only slightly reduced compared to the results in air.

Energy Spectra

The energy spectra of the FlexProbe®, recorded with nuclides used most in medicine:

18F (511 KeV-PET-Nuclide)
123I (159 KeV)
99mTc (140 keV)
111In (171 keV, 245 keV)
201Tl (70 keV)

Optional Accessories

Available Collimators

Name Dihedral Angle / Field of View Length
KOLLI-15-F 15° 33.0 mm
KOLLI-20-F 22° 32.1 mm
KOLLI-40-F (Standard) 40° 30.1 mm
KOLLI-60-F 66° 29.1 mm
KOLLI-90-F 90° 28.6 mm
KOLLI-120-F 120° 28.1 mm is a division of Nuclear Fields USA Corp.
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