Medical Laser System Requirements

Designing a versatile and reliable medical laser system platform requires a vast knowledge of the capabilities and limitations of laser technology, where most of the component solutions are not yet standardized. Furthermore, the whole design and manufacturing process should follow ISO13485 requirements and the system will be subject to a rigorous approval process confirming the safe use of the device. As a certified medical device manufacturer and fully integrated laser manufacturer, Modulight is combining its critical capabilities to build demanding medical laser devices like those needed for PCI treatment.

The PCI process requires fiber outputs to both invasive diffuser fibers (500 mW) and to a non-invasive frontal diffuser fiber (5W) and these channels should be individually addressable and calibratable. Modulight chose to use its LimeLight single-emitter subsystems as building blocks for the low power channels, whereas the high power 5W channel was realized separately. These subsystems are individually addressed by the control electronics and they selfmaintain the optimal treatment parameters set by the calibration process, providing architectural distribution of control electronics inside the system. A unique design for the higher power channel (5W), enables very high stability at a very large operating power range, from less than 100mW to 5W. (See Figure 2)

Multi-channel Dose Calibration

Fig. 3 — Treatment of head and neck cancer patient with interstitial laser light application.
Apart from multi-channel and wavelength requirements, many medical laser systems also require integrated calibration to measure the light dose radiated to the tissue. The dose is a combination of the laser power, treatment time, and tissue absorption and, therefore, requires an understanding of the tissuelight interaction. This is further complicated if varying length of diffuser fibers or illumination areas are used in the treatment. (See Figure 3)

The medical laser used houses an integrated calibration unit that allows easy dose calibration of single or multiple channels and for varying diffuser lengths from 1 to 5 cm. Calibration of multiple fibers together speeds up the treatment process but requires a careful analysis of the shadowing effects inside the calibration unit. In an invasive treatment process, the fibers are sterile and the whole calibration process has to maintain that even in the case of interrupted treatment and recalibration. The developed laser platform allows the use of a separate sterile cuvette protecting sterile fibers during the calibration process. The system also allows individual re-calibration of any channel, for example, in case of fiber breakage or contamination.

This medical laser platform supports a high-speed multi-channel treatment and calibration process. This ensures that treatment is safe and that patients are not subjected to unnecessary delays in the treatment process that, in many cases, requires invasive surgery. Shorter treatment and calibration times also result in significantly lower treatment costs because of the shorter use of expensive operating rooms and staffing.

■ Connecting Medical Laser Systems

Modulight is currently designing new platforms supporting therapeutic treatments over a range from visible blue (450 nm) to infrared wavelengths at 1,600 nm and beyond. The new system platforms will use a large area tablet-based user interface allowing easy treatment process guidance through high-definition graphics or even animation. The key design requirement is always safe and easy use of lasers in the healthcare process.

New features are being developed to allow easier safety control of the treatment and related consumables. Near-field radio frequency identification (RFID) is already a widely used technology in controlling logistics and the identification of many consumer products. Modulight further developed this technology to provide tools to control the use of approved combinations of drugs and consumables like sterile medical fibers that are critical for a safe treatment process. An integrated RFID module in a medical laser system allows for the immediate identification of an approved consumable through a wireless recognition process, and the automated set up of the system for the selected treatment parts as needed. By combining RFID functionality with an integrated wireless LAN module in a medical laser system, one can eventually track and monitor the use of consumables and their logistics globally through a centralized service center. The wireless connectivity also helps medical equipment manufacturers to actually monitor, diagnose, and service their systems remotely.

This article was written by Sampsa Kuusiluoma, Manager, New Product Introduction, Integrated Laser Solutions at Modulight, Tempere, Finland. For more information about Modulight and its laser technology, visit http://info.hotims.com/40439-166. For more information about PCI Biotech, visit http://www.pcibiotech.com.