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
Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg
New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences