Control measurements for lasers in physiotherapy

In physical rehabilitation, is diffused the skin irradiation with near infrared laser at a fluence below 140 J/cm(2), achieving a bio-stimulating effect that is due to the absorption of radiation in mitochondria rather than the simple heating of tissues. In order to deliver radiation without thermal damage of the skin, are used radiation pulses which duration does not allow heat accumulation and propagation far from the irradiated target; this requires laser sources with average power below 10 W implying a safety classification as "potentially dangerous for eye and skin", or "class 4" according to the applicable international standards. In this paper, 6 laser therapy devices, of 5 different manufactures and models have been analyzed from the point of view of actual radiation output and user safety. In each case, one or more of the characteristic declared by the manufacturer in the user manual have been found different from the actual measured value. The actual accessible energy levels have been found to be complying with risk class 3B. The impact of the new version of the Standard IEC 60825-1 (2014), is also discussed, considering in particular the possible classification in the new class 1C, and the maximum permissible levels for pulsed lasers. An extension of the measurement protocols is proposed in order to assure effective and safe use of laser in physical therapy.