Photographing the Skin During Photodynamic Therapy

Photodynamic therapy (PDT) is used to treat some types of sun-damaged skin and low-grade forms of growths. A cream is applied to the skin, and the chemical in this cream is absorbed in to the skin and converted in to a 'photosensitiser'. This photosensitiser is fluorescent, meaning that it produces red light when blue light is shone on it. By measuring how much light is given off with a camera, the investigators can determine how much photosensitiser is present in the skin. Also, it is thought that more of the chemical is converted to the active photosensitiser if the skin is warmer, so the investigators plan to measure the temperature of the skin using a thermal camera. Light is shone on to the skin and this activates the photosensitiser, treating the problem area and leaving healthy skin intact. This research will increase the investigators understanding of how PDT works, and may help the investigators to improve treatment regimens so that they can be made more effective and better tolerated

Two cameras used to take images of the skin. One, to measure the fluorescence from the photosensitiser, and the second to measure the surface temperature of the skin

Is there a correlation between body site temperature and degree of fluorescence prior to and/or during PDT

Body site temperature is measured before and during PDT (in degrees Celsius) as is fluorescence signal (in arbitrary fluorescence units). These are compared for each time point in the treatment for each patient.

Following from Outcome 1, these data for each patient will be compared with the clinical outcome (determined visually by Dermatologist) at 3 and 12 months, to see if there is a correlation between either measurements and clinical outcome.

Fluorescence and thermal cameras record field of view data, so the investigators can investigate how the fluorescence and thermal distribution in the lesions changes during treatment.

Pain (visual analogue scale 1-10 cm-1) is measured after treatment, and the investigators will check for correlations between this properties and the fluorescence and thermal readings for each patient.

inflammation (measured visually by a Dermatologist) is measured after treatment, and the investigators will check for correlations between this property and the fluorescence and thermal readings for each patient.

Inclusion Criteria: 1. Patients presenting with superficial BCC or Bowen's disease (one or two lesions and diagnosed either clinically or histologically and untreated or having had no treatment for 4 months or longer) 2. Adult males and females, >18 years only 3. Capable of giving informed consent 4. Able to understand and adhere to protocol requirements Exclusion Criteria: 1. Patients skin lesions have had previous treatment in the last 4 months 2. Unable to give informed consent 3. Known allergy to Metvix® 4. Known to have a light sensitive disorder 5. Pregnant, breastfeeding or planning to conceive

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Morton CA, Szeimies RM, Sidoroff A, Braathen LR. European guidelines for topical photodynamic therapy part 1: treatment delivery and current indications - actinic keratoses, Bowen's disease, basal cell carcinoma. J Eur Acad Dermatol Venereol. 2013 May;27(5):536-44. doi: 10.1111/jdv.12031. Epub 2012 Nov 26.

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Mamalis A, Koo E, Sckisel GD, Siegel DM, Jagdeo J. Temperature-dependent impact of thermal aminolaevulinic acid photodynamic therapy on apoptosis and reactive oxygen species generation in human dermal fibroblasts. Br J Dermatol. 2016 Sep;175(3):512-9. doi: 10.1111/bjd.14509. Epub 2016 Jul 24.

Kulyk O, Ibbotson SH, Moseley H, Valentine RM, Samuel ID. Development of a handheld fluorescence imaging device to investigate the characteristics of protoporphyrin IX fluorescence in healthy and diseased skin. Photodiagnosis Photodyn Ther. 2015 Dec;12(4):630-9. doi: 10.1016/j.pdpdt.2015.10.002. Epub 2015 Oct 20.