CrystalGuard
The control and monitoring system for Isolated Limb Perfusion (ILP)
Generally applies: the ILP procedure is only used if no other surgical or chemotherapeutical method is possible. The decision about that should be made by a team (e.g. Tumorboard) of experienced doctors of various special fields.
CrystalGuard is designed as a professional technical solution for performing surgeries following ILP with high reliability. The most essential information regarding the safety of the patient is to observe and check the “leakage rate” between the two blood circulations used by the ILP. The leakage rate is a value describing the transition of blood from the “isolated limb” to the rest of the body. Because the blood in the limb is highly enriched with extreme aggressive cytostatica, the transition rate must not exceed a certain value, due to high danger to the patient. The leakage rate is always calculated by the CrystalGuard and shown by the display.
Technical description
To measure the transition rate, the system uses the activity of radioactive tracers. The system can operate with two different tracers, Tc-99m and In-111, both together and with only one of them. To reach a reasonable accuracy rate, one tracer must be injected in both blood circulations with an intensity ratio of about 1:100 (body to limb). That must be done first after the operative isolation between them to check the isolation rate. Only after this check can the cytostatica be injected in the limb circulation. Details must be fixed by the ILP team!
There are two CrystalGuard versions, one with two detectors and one with three. All the detectors use the latest detector technology (GAGG crystals with read-out by Silicon photomultiplier Si-MPPC) which are very compact, completely in stainless steel containers and internally shielded by 11 mm of lead in all directions. This new technology shows non-temperature peak-drift, is stable against mechanical shock, doesn’t use any high voltage for operating and is simple to clean and disinfect.
The detectors operate with our universal control unit SG04 which can operate in a single mode (Tc-99m or In-111) or in a dual mode (both nuclides together).
The count rates of the control units are provided to a medical panel PC which shows, using different scales, the actual count rates of all detectors and the estimated leakage rate. The operation team can observe any phase of the treatment process.
Detectors
- The heart detector is the most essential detector for this procedure since the location is directly in front of the heart of the patient. The detector detects the actual count rate in the “body circulation” and shows any increasing of the count rate during the treatment. The output of this detector is used at every calculation of the leakage rate!
- Reservoir detector. It shows the actual activity in the “limb circulation”. In both the two-detector and three-detector version, the output is used in the leakage rate for a more precise estimation.
- Limb detector allows for checking if the limb is really in a blood circulation! Additionally, it plays a decisive role in controlling and finishing the “outwashing procedure” after the end of the treatment by the ILP process.
Responsibility
The described procedure is not a guideline or an instruction for using this method!
Note: the producer of the needed cytostatica may only provide it to a customer if the surgical team of the respective hospital has successfully completed the relevant training with a final examination!
Key features
- Rugged full solid state sensors with high efficiency
- Size: D = 68 mm (top); D = 89 mm (botton); H = 76 mm
- Weight: 2 kg, including the lead shielding
- Container: water proof, 3-10 m cable for operating and output read out, stainless steel
- Energy range: 50 keV up to 1 MeV, optimized for 140 keV (Tc⁹⁹ᵐ gamma radiation)
- Sensitivity: > 95000 cps/MBq at 140 keV
- Scintillation crystal: GAGG, D 25.48 mm³, and read out by MPPC
- Energy resolution: about 23% at 140 keV (22°C)
- Side shielding: 11 mm Pb from all sides; radiation entrance window on the downside of the detector (side shielding > 99.99% at 140 keV)
- Dual Mode checking and controlling possible
- Mounted on a medical cart
