Toshiba Aquilion CT X-Ray Tube Recommended Maintenance
The most expensive consumable part of a CT machine is the x-ray tube. It’s best to work towards extending tube life as part of your preventative maintenance plan, as the x-ray plays a pivotal role in image collection. Toshiba’s high-performance CXB tube series is a reigning champion amid the consumable market. Maximize your machine’s potential by getting to know the Toshiba Aquilion CT X-Ray Tube.
Toshiba Aquilion Life Expectancy
A typical Aquilion tube will achieve 500,000 slices in its lifetime, though counts bordering 1,000,000 are not unheard of. Systems with replacement tubes tend to fail earlier than expected, especially when cooling systems become compromised.
How long your actual x-ray tube lasts will depend on several factors. To ensure prolonged use, always limit use to a professional x-ray or radiologic technologist.
Ideal Temperatures for the Toshiba Aquilion
What makes the Toshiba Aquilion superior in its engineering characteristics is its use of a Varian tube design. Its primary feature is efficient heat removal. Within a maintained system, this feature can contribute to a longer tube life.
How efficiently a CT tube will cool is dependent on how the heat exchanger operates. Within the exchanger, a series of coils are responsible for heat dissipation. A water or glycol cooling fluid will flow through the tube’s back and into the heat exchanger to perform this transfer.
Any loose part of the heat exchanger pump is susceptible to air, slowing, or stopping the coolant flow. Thus, regular heat transfer becomes limited.
The tube must produce and absorb heat energy to create an x-ray. Should heat continue to build-up rapidly, it will first impact rotating components, which then triggers a chain reaction.
Toshiba CXB tubes come equipped with thermal sensors as a safeguard against overheating. The thermal sensor can recognize when the cooling system fails, allowing mechanics to address the root issue. Note that heat “in transit” may cause a temporary rise in temperature.
Of the Aquilion tube’s impressive features, its cooling loop appears to be its weakest link, experiencing frequent cooling line quick-disconnects. When separated, they leak, allowing fluid out and air in.
How to Manage Cooling System Health
To maintain cooling system health, regularly purge, and recharge (P/R) with every tube change. P/R will remove excess air from the exchanger coils, yielding excellent results for proper cooling. The two P/R options include:
- Varian itself will perform the P/R for a nominal sum—though you’ll have to deliver the unit.
- An on-site service engineer will perform the P/R with a purge kit from Varian. Though more convenient, this P/R method is not as precise.
Sometimes, a P/R won’t suffice, and a replacement becomes necessary. When replacing a part, perform a P/R of the component you aren’t replacing. For instance, if you’re replacing a tube, perform a P/R on the heat exchanger and vice-versa.
Preventative Temperature Measures
Always pay close attention to thermal warnings. A tube “over-temp” error will indicate that the cooling system is down and requires immediate attention. Heat exchanger errors are often severe, caused by air bubbles on the pressure sensor. Unlike “over-temp” errors, heat exchanger errors occur intermittently, without corresponding rises in tube temperatures.
Caring for Your CT X-Ray Tube
As crucial as actual use is the preparation that occurs beforehand. If you haven’t used your tube for 2 hours or longer, warm it up before a scan. This prevents thermal shock, which can lead to tube damage. Take several exposures in 30-second intervals to warm up the tube. Otherwise, you can refer to your manufacturer’s documentation for specific times and durations.
Alternatively, you can improve x-ray tube longevity by applying the minimum recommended current (mA), voltage (kVp), and exposure time during each examination. When tube currents are too high, tungsten from the filament evaporates and deposits on the glass envelope, shortening its lifespan. Employing lower mA and longer exposure times not only helps mitigate the risks of unstable operations but also improves image reception speed.
Improper Heating and Cooling
During a CT scan, a high amount of heat occurs in the anode. Avoid premature focal track wear or damage by strictly adhering to manufacturer-recommended levels of operation.
Damaging or pitting the focal track can result in radiation output falloffs when electrons from the filament strike the pitted surface. Staying within your system’s heating and cooling curves can prevent severe melting and excessive heat transfer.
Rotor Operations
Note the time between rotor brake cycles, avoiding long intervals between spot-films. Paying close attention to rotor operations can reduce overheating that occurs within the stop-and-start process. When your rotor comes to a stop, wait for 30 to 40 seconds between each sequence.
When Your X-Ray Tube Needs Replacement
Your x-ray tube may require a replacement if:
- There is a build-up of tungsten in the internal surface of the glass tube window.
- Your tube is producing gas, which hinders its ability to act as a vacuum.
- You can hear oil being sucked into the tube insert, which might indicate a punctured tube.
- There are cracks and stress fractures on your tube.
- There is oil in areas; there shouldn’t be any.
Conclusion
Unfortunately, manufacturers have yet to kick the “consumable” aspect of an x-ray tube. However, regular maintenance can help sustain your Toshiba Aquilion CT X-Ray Tube for years.
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