The principles of physics and precision engineering have allowed many technologies to enter standard treatment regimens for a range of diseases. Recently, a new type of technology has been accredited as safe and efficient routine procedure in dermatology in Europe: cold physical plasma. Several accredited devices successfully restrain the powerful energy of plasmas to make them available for therapeutic purposes. Herein, we introduce an introduction to the concept of cold physical plasmas and highlight some fields of their medical applications.

The generation of cold physical plasma at atmospheric pressure (cold atmospheric plasma: CAP) generates different reactive molecular species as well as radiation in the ultraviolet (UV) range. The therapy of tumor diseases has proven to be a new promising area of application for CAP treatment. With regard to the routine use of CAP in cancer therapy, however, application safety must be ensured both for the patient and for the operator. In this study, the intensity of UVC radiation of the CAP device MiniJet-R (HF Technik, Aachen, Germany) was measured in the range from 220 to 280 nm depending on various device-specific parameters. Depending on the distance to the CAP flame, the UVC intensity reaches values up to 124.5±11 mW m−2. It should be noted here that the UVC radiation generated by the CAP is emitted in all orientations in the room but is also shielded by the geometry of the handpiece of the CAP device. The device-specific settings for the flow rate of the carrier gas, argon, and the power level at the high-frequency (HF) generator of the CAP device also influence the intensity of the UVC radiation. With regard to the medical use of the CAP device, it can be stated that there is an exposure to UVC radiation, which, depending on the duration of treatment, can also be above the maximum value legally specified in Europe. Shielding components on the CAP device can reduce UVC exposure to the operator as well as adverse side effects to the patient.

Background: Physical plasma is a mixture of reactive particles and electromagnetic radiation. Due to the antimicrobial, immunomodulatory, anti-inflammatory, wound-healing promoting, and antineoplastic effects of body tempered physical plasma under atmospheric pressure (cold atmospheric plasma: CAP), CAP therapy is increasingly becoming the focus of surgical and oncological disciplines. However, when applied in practice, a potential emission of harmful noxae such as toxic nitrogen oxides must be taken into account, which was investigated in the following study. Materials and Methods: MiniJet-R Ar CAP device was characterized with respect to NO X -specific spectra, ultraviolet radiation C (UVC) intensity in the range of 200-275 nm and the formation of NO X gases. Instrument-specific parameters such as gas flow, energy setting of the highfrequency generator, and flow rate of the carrier gas Ar were varied. To test the toxic properties of the NO 2 concentrations formed by CAP, SK-OV-3 human ovarian cancer cells were incubated with different NO 2 concentrations and cell growth was monitored for 120 h. Results: The operation of MiniJet-R led to the formation of NO 2 in the proximity of the CAP effluent. Synthesis of NO led to a NO-specific spectrum in the range of 100-275 nm, whereby UVC radiation produced reached intensities of up to 90 mW/m 2 . NO gas itself, however, was not detectable, as it was converted to NO 2 rapidly. Cell culture incubation experiments demonstrated that NO 2 in these concentration ranges had no influence on the cell growth of human cancer cells. Conclusion: Although no limit values were exceeded in the present study, the emission of high-energy UVC radiation and toxic NO 2 is a risk factor with regard to the legal regulations on workplace protection (operator hazard) and the approval of medical devices (patient hazard). This is important for considerations regarding treatment frequency and duration. The growth inhibitory effect of CAP treatment on human cancer cells principally suggests a medical application of the MiniJet-R device, although more extensive studies will have to follow.Physical plasma is a mixture of particles of a carrier gas and ambient air with different ionization and excitation states, as well as electromagnetic radiation of different wavelengths including ultraviolet radiation C (UVC). In medical applications, body-tempered ('cold') plasmas up to about 40˚C under normal atmospheric pressure (cold atmospheric plasma: CAP) are utilized (1, 2). CAP has antimicrobial, immunomodulating, anti-inflammatory, wound-healing promoting, and antineoplastic effects on biological tissue and is therefore tested for its applicability in various medical fields. Due to the physical properties of CAP and against the 2591