In 2015, a study showed that Krypton-Chloride (KrCl) excimer lamps could induce erythema and basal layer DNA damage in human skin. Later studies found that filtering out longer wavelength emissions from these lamps resulted in no acute skin effects. However, there is a limited understanding of how much to reduce unwanted emissions and which wavelengths are important.
View Article and Find Full Text PDFPhototherapy clinics administer ultraviolet (UV) light to patients using phototherapy cabinets. The UV radiation from these cabinets is reflected on the white ceiling tiles of the clinic and is then redirected toward both staff and patients in the area. This is particularly problematic for clinical technologists who must undertake dosimetry in these areas and have a specific time (often as low as 30 min) before they reach their maximum exposure limit.
View Article and Find Full Text PDFSignificance: Glioblastoma (GBM) is a rare but deadly form of brain tumor with a low median survival rate of 14.6 months, due to its resistance to treatment. An independent simulation of the INtraoperative photoDYnamic therapy for GliOblastoma (INDYGO) trial, a clinical trial aiming to treat the GBM resection cavity with photodynamic therapy (PDT) via a laser coupled balloon device, is demonstrated.
View Article and Find Full Text PDFFar-UVC, from filtered Krypton-Chloride lamps, is promising for reducing airborne transmission of disease. While significant research has been undertaken to investigate skin safety of these lamps, less work has been undertaken on eye safety. There is limited data on human eye safety or discomfort from the deployment of this germicidal technology.
View Article and Find Full Text PDFUltraviolet-C (UVC) radiation can effectively inactivate pathogens on surfaces and in the air. Due to the potential for harm to skin and eyes, human exposure to UVC should be limited within the guideline exposure limits produced by the International Commission on Non-Ionising Radiation Protection (ICNIRP) or the American Conference of Governmental Industrial Hygienists (ACGIHs). Both organisations state an effective spectrally weighted limit of 3 mJ cm, although the spectral weighting factors of the two organisations diverged following a revision of the ACGIH guidelines in 2022.
View Article and Find Full Text PDFMany infectious diseases, including COVID-19, are transmitted by airborne pathogens. There is a need for effective environmental control measures which, ideally, are not reliant on human behaviour. One potential solution is Krypton Chloride (KrCl) excimer lamps (often referred to as Far-UVC), which can efficiently inactivate pathogens, such as coronaviruses and influenza, in air.
View Article and Find Full Text PDFAn increase in the use of light-based technology and medical devices has created a demand for informative and accessible data showing the depth that light penetrates into skin and how this varies with wavelength. These data would be particularly beneficial in many areas of medical research and would support the use and development of disease-targeted light-based therapies for specific skin diseases, based on increased understanding of wavelength-dependency of cutaneous penetration effects. We have used Monte Carlo radiative transport (MCRT) to simulate light propagation through a multi-layered skin model for the wavelength range of 200-1000 nm.
View Article and Find Full Text PDFIt has been demonstrated in laboratory environments that ultraviolet-C (UVC) light is effective at inactivating airborne viruses. However, due to multiple parameters, it cannot be assumed that the air inside a room will be efficiently disinfected by commercial germicidal ultraviolet (GUV) systems. This research utilizes numerical simulations of airflow, viral spread, inactivation by UVC and removal by mechanical ventilation in a typical classroom.
View Article and Find Full Text PDFThis study aims to investigate, with computer modeling, the DNA damage (assessed by cyclobutane pyrimidine dimer (CPD) formation) from far-ultraviolet C (far-UVC) in comparison with sunlight exposure in both a temperate (Harwell, England) and Mediterranean (Thessaloniki, Greece) climate. The research utilizes the published results from Barnard et al. [Barnard, I.
View Article and Find Full Text PDFPhotodiagnosis Photodyn Ther
June 2021
Daylight photodynamic therapy is an effective treatment for actinic keratoses and relies on a minimum PpIX-effective light exposure dose being delivered during treatment. As such, daylight dosimetry is an important aspect of this treatment. Relatively simple measurements of illuminance may be converted to PpIX-effective irradiance, and subsequently exposure dose, via a conversion model (the O'Mahoney model).
View Article and Find Full Text PDFFar-UVC devices are being commercially sold as "safe for humans" for the inactivation of SARS-CoV-2, without supporting human safety data. We felt there was a need for rapid proof-of-concept human self-exposure, to inform future controlled research and promote informed discussion. A Fitzpatrick Skin Type II individual exposed their inner forearms to large radiant exposures from a filtered Krypton-Chloride (KrCl) far-UVC system (SafeZoneUVC, Ushio Inc.
View Article and Find Full Text PDFIt is possible to enhance topical drug delivery by pretreatment of the skin with ablative fractional lasers (AFLs). However, the parameters to use for a given AFL to achieve the desired depth of ablation or the desired therapeutic or cosmetic outcome are hard to predict. This leaves open the real possibility of overapplication or underapplication of laser energy to the skin.
View Article and Find Full Text PDFUVR exposure is a widely applied technique in clinical and preclinical studies. Such experimental conditions provide crucial information on the biological responses of skin and cell models, which may then be extrapolated and interpreted, for example, in the context of equivalent daylight exposures. It is therefore important to fully understand the characteristics of UVR and the principles behind correct and appropriate UVR exposure in experimental settings.
View Article and Find Full Text PDFPhotodermatol Photoimmunol Photomed
March 2021
Photodiagnosis Photodyn Ther
September 2020
Background: Actinic keratosis (AK) affects one quarter of over 60 year olds in Europe with the risk of transforming into invasive squamous cell carcinoma. Daylight photodynamic therapy (dPDT) is an effective and patient preferred treatment that uses sunlight to clear AK. Currently, there is no standardised method for measuring the light received during treatment.
View Article and Find Full Text PDFPhotodermatol Photoimmunol Photomed
November 2020
Photochem Photobiol
March 2020
Daylight photodynamic therapy (DPDT) is an effective and patient preferred treatment for the management of field change actinic keratosis. An important factor in DPDT is light dosimetry, to ensure that patients receive sufficient daylight for effective treatment, and this is the focus of the contribution to this issue by (La Rochelle et al. [2019] Photochem.
View Article and Find Full Text PDFPharmaceuticals (Basel)
September 2019
Successful daylight photodynamic therapy (DPDT) relies on the interaction of light, photosensitisers and oxygen. Therefore, the 'dose' of light that a patient receives during treatment is a clinically relevant quantity, with a minimum dose for effective treatment recommended in the literature. However, there are many different light measurement methods used in the published literature, which may lead to confusion surrounding reliable and traceable dose measurement in DPDT, and what the most appropriate method of light measurement in DPDT might be.
View Article and Find Full Text PDFPhotodiagnosis Photodyn Ther
September 2019
Background: Daylight photodynamic therapy (dPDT) is an effective treatment for field-change actinic keratoses (AK), with similar efficacy to conventional PDT but lower patient pain scores. Whilst AK occur consequent to chronic solar ultraviolet (UV) exposure, paradoxically solar visible radiation is used during PDT.
Objectives: To investigate the nature and levels of UV exposure, both erythemal UV and UVA, occurring during dPDT.
Photodermatol Photoimmunol Photomed
July 2019
Background: Phototherapy and photochemotherapy are commonly used treatment modalities for a range of chronic skin conditions. Whilst undergoing ultraviolet radiation exposure, patients can wear personal protective equipment. Face shields in combination with other forms of skin cover may be worn to provide both skin and eye protection.
View Article and Find Full Text PDFPhotodiagnosis Photodyn Ther
September 2018
Objectives: Implementation of daylight photodynamic therapy (dPDT) is somewhat limited by variable weather conditions. Light sources have been employed to provide artificial dPDT indoors, with low irradiances and comparable treatment times to dPDT. Uniform light distribution across the target area is desirable in effective treatment planning, particularly for large areas.
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