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Frequently Asked Questions


1. Which nuclides can the surgical gamma probe detect?

The Crystal Probe can detect energies between 70 keV and 511 keV. Different probes are designed for use with different energies. For example, the wireless probe is optimized for use with Tc-99m, the Beta probe is used for low energy ranges (<50keV) and beta radiation (<MeV), while the PET probe is used for higher energies (365keV), etc.

2. Is it necessary to set the nuclide on the control panel?

No, the control unit is completely automatic. Everything is preset for optimal use based on the probe you are using.  You can manually change he nuclide if the displayed nuclide is not desired by simply clicking a button on the control unit.  There are 10 preset energy thresholds (I-125, Tl-201, Ga-67, Tc-99m, I-123, In-111, I-131, In-113m, PET, Co-57). Additional energy threshold according to the customer’s needs can be installed by the manufacturer.

3. Why is it important to have a collimator?

The tissue surrounding the radio labeled lymph node also radiates from the radio pharmaceutics. Reducing the opening angle of the probe by different collimator sleeves enables the suppression of this radiation and improves the ratio node-to-background signal.  Detecting a smaller window of radiation, rather than detecting all radiation emitted, is a much more effective way of finding the sentinel lymph node.

The Crystal standard probe (CXS-OP-SZB) has a collimation angle of 40º and is to be found most suitable for sentinel lymph node detection procedure (other collimation angles are available). For more flexibility we offer the Flexible Gamma probe (CXS-OPSZF) with changeable collimation angles of 20º, 40º, 60º.

4. How do I change the collimator?

The straight probe, flex probe and PET probe come with optional exchangeable collimator sleeves. To change the collimator sleeve simply screw off the current sleeve and replace it with the desired sleeve.

5. What is the life time of the batteries?

The life time of the rechargeable batteries ranges between 4 and 5 years, or for about 200 charging cycles.

6. How can the lifetime of the batteries be extended as much as possible?

Please make sure that the batteries always have a charging level as high as possible. It is recommended to recharge the batteries to full capacity immediately after each use and before each storage. The manufacturer of the batteries suggests to keep the batteries connected with the mains voltage, even when the system is not used. Over-charging is not possible! A very deep discharging of the batteries must be avoided because this leads to the destruction of the batteries.

7. What can happen if the control unit’s batteries are drained?

ue to insufficiently high voltage the electronics will not work properly and can create faulty signals like unexpected erratic counts and permanent sound even when no radiation is present. To avoid this make sure the battery is charged or plug the control unit into mains during surgery.

8. Is it possible to operate while the system is connected to the charger?

After a long usage period (>10 hours) the batteries will run low. In this event, the operation with the system can continue by connecting the control unit’s battery charger into a power outlet. 

9. Are there any wearing parts?

No, there are not.

10. Which probe parts may be sterilized; which methods are allowed?

The collimator sleeve, made of stainless steel with an integrated tungsten collimator, may be sterilized with the usual methods (plasma sterilization, steam sterilization at 150°C and 4 bar).

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 disinfection by solvents cannot be avoided (should be an 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 wand is possible. However, damage of the probe may not be avoided.

11. Does the system need to be re-calibrated?

The Crystal Probe System does not require any calibration.  Certain government agencies around the world require documentation showing the testing for surgical equipment on a regular basis.  In this case, the instruction manual shows a simple test that can be done that meets the legal regulations. It can be done on site by the surgeon or surgical technician.

12. Which collimation should I use?

This depends on type of the surgery, the specific geometric conditions of the radio labeled tissue, the applied total dose, the time dependent change of the nuclide's distribution, and also on the experience of the surgeon. Generally, it is suggested to work 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.

13. What can be measured with the probe?

The use of a surgical gamma probe makes sense with the following surgeries. There are some suggestions how the patients should be prepared (according to Dr. rer.nat. D. Lange, PhD, Nuclear Medical Dept., Heidelberg University Germany):

  1. For Nidus Operations approx. 600 MBq Tc-99m-MDP has to be injected i.v. approx. 3 hours before the operation should start. In the case the nidus is located near the bladder, e.g. at the head of the femur, the continuous evacuation of the bladder by a catheter during the operation is suggested. So, an increased activity near the operation spot and therefore misinterpretations of the measurements are avoided.
  2. For Sentinel Lymph Nodes the activity - e.g. Tc-99m-Nanocoll - is injected subcutaneous at least 1 hour before the operation should start (For the Mamma-Ca. e.g.. the application has to be done right next to the primary spot of the Mamma-Ca, approximately in direction of the assumed lymph outflow).
  3. Melanoma Metastases
    Appr. 40 MBq Tc-99m-Nanocoll are injected subcutaneously. The Injection has to be done sufficiently long before the operation, the time scale can be defined by the preliminary examination by scintigraphy. If necessary the patient must move his extremities for a faster outflow of the lymph and storage in the lymph nodes.

14. Are there any sources of interference?

A surgical probe is a very sensitive mechanical and electronic device, i.e. usage and storage should be done accordingly. Very efficient amplifiers and subsequent electronics in the hand piece of the probe allow an efficient conversion of the γ-radiation in electronic signals. The same sensitive electronics however amplify other electro-magnetic radiation coming from sources near the probe, too. In order to avoid fault signals all electro-magnetic sources near the probe should be removed. Please refer to the users manual paragraphs "Installation Location" and "Safety Instructions".

15. How should the system be stored?

The system should be packed and stored in the blue hard cover case that comes with the system. In the event you are transporting the system, we recommend the use of white plastic protection sleeve for the surgical probe. The system comes with a surgical probe holder that you can attach to the control unit.

16. Does the system have a certification of the EC?

The system CXS-SG04 was developed and manufactured in Germany, taking maximum precision and security aspects into consideration. Each system underlies a single inspection at the Notified Body 0633 (TU Berlin, Prüf- und Zertifizierungsstelle für Medizinprodukte) 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 labeled with the CE-mark in combination with the identification No. 0633. is a division of Nuclear Fields USA Corp.
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