Frequently Asked Questions (FAQ) about the Crystal Probe -automatic-

Answers

1. All probes (Straight Probe, flexible probe FlexProbe, Laparoscopic Probes, Wireless Probes) are sensitive to all nuclides with energies between 70 keV and 511 keV. The standard collimator sleeve for the probes CXS-OP-SP und CXS-OP-FP however has an optimized side shielding only with the use of 99mTc (Transmission <0,1% @140 keV, also for 57Co and 201Tl)

2. Yes. In order to achieve the optimum side shielding also at using of radio nuclides with higher y-energies (111In: 245 keV, 131I: 364 keV, PET: 511 keV) it is necessary to use a collimator sleeve which has a different design than the standard collimator sleeve with an accordingly designed tungsten collimator. Measurements with gamma-energies between 25 keV and 70 keV and with beta-radiating nuclides require a completely different probe (Beta-Probe) because the absorbing mechanisms for those gamma- and beta-radiation differs from those in the higher gamma-energy ranges. The needed parts for both gamma-energy ranges < 50 keV and 511 keV and for beta-measurements are available upon request.

3. The aim of the gamma guided surgery is to localize nuclide enrichments (e.g. sentinel nodes) as exactly as possible. For this purpose the ratio of its signal to background should be as high as possible. The background signal also includes scattered gamma-radiation with less energy and changed direction. This low energy part of the spectrum can be suppressed by setting an energy threshold right below the photo-peak of the used nuclide. An upper threshold energy is defined in order to suppress signals from ambient high energy events with unknown origin. The preset data for available nuclides are stored electronically in an internal table and recalled by selecting an item (Instruction Manual, part 4.2 Functions and Features "Nuclide Selection").

4. The nuclide table items are named by nuclides that are representative for a group of nuclides with similar energies. Please read the manual (part "Technical Data") for details.

5. The table position "ALL" represents an energy range close above the noise-energy of the detector (60 keV). Using this position enables to detect all gamma-radiation with energies above this threshold, and no suppression of any part of the spectrum is done. In this way one has a higher signal for any nuclide than with a switch position specific to the used nuclide, but the direction selectivity might be reduced. This setting is intended to enable experienced users to detect even more exotic isotopes.

6. No. The energy thresholds are implemented by the manufacturer and cannot be changed by the user. However, an additional energy threshold according to the customer's needs can be installed on request.

Collimation

7. The collimation sleeve acts in three different ways:

It contains the needed collimator for maximal side shielding and to obtain the optimal view angle of the probe.
It is unscrewable and can thus be sterilized separately, protecting the patient in case of failures of the sterile cover.
It protects sensitive inner parts of the probe.

8. The tissue parts surrounding the radio labelled lymph node also radiates by the radio pharmaceutics which are not enriched in the sentinel node. Reducing the opening angle of the probe by different collimator sleeves with different shapes enables the suppression of this radiation and improves in this way the signal ratio node-to-background. The detection of the node is easier then, but the search might be more difficult because it may easily happen that simply the target is missed during the scanning of the tissue. The localization of the SLN's by a gamma scintigraphy as exactly as possible prior to the operation is therefore strongly recommended.
Moreover, a small viewing angle also enables triangulation techniques, in order to explore the depth of an identified lymph node.

9. The collimation can be easily changed by replacing the standard collimator sleeve by other differently designed and shaped collimator sleeves. Probes are usually delivered with an optimized standard collimator angle of 40°. We also provide collimators with 15°, 30°, 40°, 60°, 90° angle, others on customs request.

10. Yes. Both probes with changeable collimator sleeve (Straight Probe CXS-OP-SP and FlexProbe CXS-OP-SP) consider the most, also different, requirements to both a surgical and a high sensitive measuring instrument in an optimal design. Both the safety of the patient and the safety of the probe are assured by the polished and sterilizable stainless steel probe sleeve that hide all the functional and non-sterilizable parts of the probe. A change of the collimation is only possible when the frequently used sterile plastic cover can be removed, another collimator sleeve can be screwed on and another sterile plastic cover can be applied again. This could only be done out of the sterile operational area. Because this can turn out somewhat complicated, we therefore suggest to prepare two probes with different collimator sleeves according to the planned approach for the specific surgery.

11. Reducing the angle of view is to suppress the radiating background around the node as much as possible. Following this suppression a lower signal has to be expected. Thus, reducing the angle of view has the desired effect to increase the node-to-background ratio of the signal to get a better appearance of the node. However, on the other hand this is connected with a reduction of the probe's own sensitivity: A smaller angle of view can only be achieved by adding a cylindrical "ray guide" in front of the entrance window of the sensitive scintillation crystal and, if necessary, by a smaller cross-section of that ray guide. That of course means the crystal is then in a larger distance from the radiating sources to be looked for, and this reduces the intensity of the radiation (more exact: the reduction goes with the square of the distance increase).. Corresponding an enlargement of the opening increases the number of collected gamma photons.

Accumulators

12. The life time of the rechargeable batteries ranges between 6 and 8 years, or for about 400 full recharging cycles.

13. Please take care that the batteries always have a charging level as high as possible. That's why it is recommended to recharge the batteries to full capacity immediately after use and before each storage. The manufacturer of the accumulators suggests to keep the accumulators connected with the mains voltage (over the charger unit) even when the system is not in use. If this is not possible the charging status must be checked regularly. A very deep discharging of the accumulators must be prevented because this leads to the destruction of the accumulators. Sophisticated energy saving routines in the software as well as the alarming signals can not replace a regular charging, but minimize the risk of failure.

14. Due to the insufficiently low voltage the electronics does not longer work properly and can produce fault signals like unexpected erratic counts and permanent sound even if no radiation is present. Permanent internal checks of all relevant voltages prevent such situations by giving alarm signals or switching off the control unit automatically.

15. YES. When after a longer period (>15 hours) of use the accumulators are at low charge the operation with the system can be continued by connecting it to the mains voltage by means of the battery charger. For this purpose switch off the system, plug in the battery charger, connect the charger with the mains voltage, switch system on again (ready to go after 15 seconds initialisation of the electronics). Don't forget to connect then the Control Unit's "Ground" pin (yellow-green marks) with the "Ground" connector of the Operating Room!

Construction

16. Straight Probe CXS-OP-SP, flexible probe FlexProbe CXS-OP-FP, (both with D= 15 mm), straight Laparoscopic Probes with 0°, 45° und 90° "field of view" (D=10 mm), Beta-Probe (D= 12 mm). For the straight probe CXS-OP-SP are PET-Collimator sleeves available. The Laparoscopic Probes can be used for minimal-invasive surgeries (MIC) by using a trocar sleeve for diameter 10 mm.

17. No, there are not.

18. The collimator sleeve has some essential functions:

- protect the inner detector head mechanically
- makes the needed side shielding to avoid the detection of radiation from the side
- makes the collimation of the detector "field of view" (direction sensitivity)
- can be sterilized separately from the probe..

Preparing for the measurement

19. The collimator sleeve of stainless steel with integrated tungsten collimator may be sterilized with the usual methods (plasma sterilization, steam sterilization at 150°C and 4 bar). Generally only the collimator sleeves should be sterilized. The use of several sterilized sleeves is recommended to have the system ready for use even when a collimator sleeve is off for sterilisation. The detector head and the "stand pipe" that are normally protected by the probe sleeve are not allowed to be disinfected by any liquids. If a disinfection by solvents cannot be avoided (should be the exception!) please note the following instruction: The end of the detector head has to be sealed properly by adhesive tape. The probe must be held with its head downwards. Now a careful disinfection with a wad is possible. However, a damage of the probe cannot be excluded, nevertheless..

20. Please test regularly the system's function according to paragraph "Function Test" in the Instruction Manual.

Needed is a control unit, the probe with the original collimator sleeve as delivered, and a calibration source with known activity (57Co oder 99mTc). After connecting the probe with the control unit it is switched on:

Check battery status - if necessary charge battery first or continue with external power supply.
Mount a 57Co source with known activity into the provided adapter, fix the adapter reproducibly onto the probe tip to a well defined position.
Measure the countrate using the procedure "Test" (press "Test" button on back panel for >1 sec). The displayed value after the 100 sec measuring period represents the precise averaged countrate for this 100 sec integration time. Use this value either with the provided Excel spread sheet or with the calculation procedure according to the User Manual section 8.3 to determine the actual sensitivity of the probe in "counts/ sec*MBq" units. This value must agree within a 5% deviation range with the calibrated value in the documentation provided by the manufacturer (" Ausgangsprotokoll/Measurement report").
Check sound and display functionality.
Please perform this stability test and the functionality check on a regular basis. Protocol it.

21. This depends on type of the surgery, the specific geometric conditions of the radio labelled tissue, the applied total dose, the time dependent change of the nuclide's distribution, and also on the experience of the surgeon. Generally, it can be suggested to start with standard collimator sleeve (40°) in order to get a faster survey of the nuclide distribution. To distinguish between nuclide enrichments closer to each other a collimator sleeve with a smaller opening angle can be chosen later. At very low activities we recommend collimator sleeves with larger opening angle (60°, 90°) due to the enhanced collection properties and thus higher sensitivity.

Measurement

22. Crystal Gamma Probes detect and measure local enrichments of different radioactive nuclide's within tissue in all parts of the human body. The probes comply to the "Medical Guidelines for Nuclear Medical Applications and Surgery", the user can select at the control unit for which kind of specific nuclide the probe has to be sensitive for.

23. A surgical probe is a very sensitive mechanical and electronic device, i.e. usage and storage should be done accordingly (definitely it has to be avoided to drop the probe or to apply any hard pushes!). Very efficient amplifiers and subsequent electronics in the hand piece of the probe allow an efficient conversion of the gamma-radiation into electronic signals. The same sensitive electronics however amplifies other electro-magnetic radiation coming from sources near the probe, too. In order to avoid fault signals all strong electro-magnetic sources near the probe should be removed. For detailed informations please refer to the manual paragraphs "Installation Location" and "Safety Instructions".

Miscellaneous

24. When the system won't be used for a longer period we recommend it's being packed and stored in the delivered hard cover case to avoid any mechanical impacts to the system. The sensitive parts of the hand probe should be protected by screwing on the delivered plastic protection sleeve. When the system is used regularly please pay attention to a safe stand, the hand probe with the fixed plastic protection sleeve can be stored in the delivered probe holder, that can be mounted to the control unit by the adhesive strip under the holder plate.

25. Yes. The Gamma Probe System "Crystal Probe -automatic-" SG04 was developed and manufactured taking maximum precision and security aspects into consideration. Each system underlies a single inspection by the Notified Body 0633 (BerlinCert, Prüf- und Zertifizierungsstelle für Medizinprodukte GmbH) according to the directive 93/42/EEC, annex IV. Copies of the manufacturer's final inspection, of the test protocols on the type examination and on the MPK classification acc. to §13 MPG (class IIa), and of the EC Verification Certificate are included with each delivery. Each certified system is labelled with the CE-mark in combination with the identification No. 0633. Additionally, the Gamma Probe System "Crystal Probe" is listed from the FDA, the SFDA (China), in Japan and Korea.

26. The manufacturer warrants that the Gamma Probe System "Crystal Probe -automatic-" SG04 and its parts are free from defects regarding to material and workmanship for 24 months from the date of delivery. For EU Countries Only: In case of the regular Metrological Check MTC of the Gamma Probe System (see users manual for details) we perform a recall.

27. At a defect or failure:

Contact the service personnel of Crystal Photonics GmbH (phone, e-mail, fax, mail – adresses see above)
Order an exchange system (if necessary it's delivered within 24 h – at least in Germany – ask your local distributor!)
After reception of the exchange system repack your defective system and send to Crystal Photonics, within 24 h we perform an error analysis and send a reparature offer
The exchange system stays in your facility during repair. Fees are depending on warranty or regular repair conditions.

28. To all customers in Germany we offer our 24h exchange service, regardless what the reason for the defect in your Crystal Probe system is. In other countries please contact your local distributor. This way you can plan your workflow with highest reliability.

29. For safety reasons our engineers can do any maintenance or repair at the surgical probe only when the probe is cleaned and sterilized. If the system is returned for maintenance or repairing the delivery must include a certificate that the probe has been shipped in a cleaned and sterilized status.

30. Yes. There is a regularly installed USB-interface at the Control Unit SG-04. This enables the user to control the whole measurement by means of a graphical user interface (Visual Count) and to store the measurement data together with the patient data for further processing. The connection to the PC or a Laptop can be established by every USB-cable. The measuring software "Visual Count" is provided together with the optional USB-interface on request.

[ Version: 2011-11-09-A ]

Frequently Asked Questions (FAQ) about the Crystal Probe -automatic-

Nuclides

Collimation

Accumulators

Construction

Preparing to the measurement

Measurement

Miscellaneous

Answers

Collimation

Accumulators

Construction

Preparing for the measurement

Measurement

Miscellaneous