High power femto-second laser pulses used for in vivo nonlinear optical imaging can form DNA products, which may lead to carcinogenesis. A modified cancer risk model now shows that the cancer risk is negligible above that due to regular sun exposure.
In the field of biomedical imaging, nonlinear optical (NLO) imaging is gaining importance for applications such as visualizing collagen, elastin and cellular metabolic activity. The nonlinear processes needed for NLO imaging like multi-photon excitation (MPE) and second harmonic generation (SHG), require an extremely high concentration of NIR photons to excite biological fluorophores.
While conventional lasers could lead to overheating and tissue destruction, femto-second (fs) pulsed lasers conveniently provide the high photon fluxes. The harmful effects are restricted to the irradiated tissue and do not have long term effects. Yet, studies have shown that MPE processes can form UV photoproducts from DNA such as cyclobutane pyrimidine dimers (CPDs) which may eventually lead to carcinogenesis. Thus, how save are NLO biopsies?
To evaluate these safety aspects, a team from Erasmus Medical Centre, Rotterdam and from Utrecht University (The Netherlands) estimated the risk of squamous cell cancer induction in skin following nonlinear optical imaging. First, it had to be considered, that CPDs are routinely produced in human skin by the UV component of sunlight – exposure to sunlight already causes a certain risk for skin carcinogenesis, especially squamous cell carcinoma (SCC). Therefore, the scientists decided not to evaluate an absolute carcinogenic risk due to NLO imaging, but to estimate the relative carcinogenic risk of SCC from NLO imaging above the risk due to regular sunlight exposure.
As a base, they chose an established carcinogenic risk model for humans, which estimates risk from exposure to continuous wave (CW) laser. This model was modified and expanded. Instead of CW UV laser radiation, the cumulative radiation received due to pulsed NIR wavelengths from nonlinear biopsies was considered. The derived model is unique because it assesses the risk of CPD related carcinogenesis due to both 2- and 3-photon effects.
To assess how effective NIR femto-second laser pulses are at inducing carcinogenic DNA lesions, the authors compared the levels of DNA mutations (CPDs) induced in Chinese Hamster Ovary (CHO) cells in vitro by pulsed NIR from NLO imaging with those induced by regular CW UV.
The newly derived risk model indicated that the increase in CPD-induced SCC risk from NLO biopsy is negligible above that from regular exposure to UV radiation in sunlight. The relative risk from 40 or more nonlinear biopsies over is notably higher, but this increase is still lower than the risk arising from sunbathing or having an outdoor profession.
However, it has to be considered that the risk could become significant if the NLO biopsies are performed without discretion, i.e. by using unnecessarily high energy fluence for imaging, performing too many scans over the same tissue site or carrying out excessive NLO biopsies. The authors conclude that it is necessary to delineate an efficient protocol for NLO biopsy in the clinic to ensure its efficacy as a diagnostic tool and also minimize possible long-term effects. (Text contributed by K. Maedefessel-Herrmann)
See the original publication: Giju Thomas, Oleg Nadiarnykh, Johan van Voskuilen, Christopher L. Hoy, Hans C. Gerritsen, and Henricus J. C. M. Sterenborg, Estimating the risk of skin cancer induction following nonlinear optical imaging, J. Biophotonics 7:7, 492-505 (2014); DOI http://onlinelibrary.wiley.com/doi/10.1002/jbio.201200207/pdf
Regina Hagen | Wiley
Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn
New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences