Ultraviolet phototherapy: review of options for cabin dosimetry and operation

Phototherapy for vitiligo: A narrative review on the clinical and molecular aspects, and recent literature

BACKGROUND

Vitiligo is characterized by depigmented patches resulting from loss of melanocytes. Phototherapy has emerged as a prominent treatment option for vitiligo, utilizing various light modalities to induce disease stability and repigmentation.

AIMS AND METHODS

This narrative review aims to explore the clinical applications and molecular mechanisms of phototherapy in vitiligo.

RESULTS AND DISCUSSION

The review evaluates existing literature on phototherapy for vitiligo, analyzing studies on hospital-based and home-based phototherapy, as well as outcomes related to stabilization and repigmentation. Narrowband ultra-violet B, that is, NBUVB remains the most commonly employed, studied and effective phototherapy modality for vitiligo. Special attention is given to assessing different types of lamps, dosimetry, published guidelines, and the utilization of targeted phototherapy modalities. Additionally, the integration of phototherapy with other treatment modalities, including its use as a depigmenting therapy in generalized/universal vitiligo, is discussed. Screening for anti-nuclear antibodies and tailoring approaches for non-photo-adapters are also examined.

CONCLUSION

In conclusion, this review provides a comprehensive overview of phototherapy for vitiligo treatment. It underscores the evolving landscape of phototherapy and offers insights into optimizing therapeutic outcomes and addressing the challenges ahead. By integrating clinical evidence with molecular understanding, phototherapy emerges as a valuable therapeutic option for managing vitiligo, with potential for further advancements in the field.

Quantification of narrow band UVB radiation doses in phototherapy using diacetylene based film dosimeters

Narrow band ultraviolet B (NB UVB) radiation doses are administered during phototherapy for various dermatological ailments. Precise quantification of these doses is vital because the absorbed irradiation can cause adverse photochemical reactions which can lead to potential phototherapeutic side effects. The paper presents development of diacetylene based dosimeter for the determination of therapeutic NB UVB doses during phototherapy. The amide terminated diacetylene analogues have been synthesized by tailoring them with different functional groups. The synthesized diacetylene monomers have been introduced in a polyvinyl alcohol binder solution to obtain a film dosimeter. The influence of different headgroups on the colorimetric response to UV radiation has been studied. Among all the synthesized diacetylene analogues, the naphthylamine substituted diacetylene exhibited excellent color transition from white to blue color at 100 mJ cm-2 NB UVB radiation dose. The developed amide films can be easily pasted on multiple sites of the patient's skin to monitor doses during phototherapy simultaneously at different anatomical regions. The digital image processing of the scanned images of the irradiated films facilitates rapid dose measurement which enables facile implementation of the developed film dosimeters and promising application in routine clinical dosimetry.

A thermal radiation exchange model of whole-body UV phototherapy

A novel model of the skin dose in whole-body UV phototherapy treatment cabins is presented. The model is based on an analysis of the thermal radiation exchange between two surfaces, in this case the UV source and the patient. It is shown to allow analytical treatment of the multiple internal reflections in a treatment cabin that account for around 40% of the skin irradiance. The model provides predictions of the absolute irradiance at the skin and shielding factors in seven different UVA and NB-UVB cabins that are within 6% of those measured using a calibrated radiometer and within 12% for all nine cabins. The model predicts reducing skin irradiances with increasingly patient size, a trend demonstrated in clinical measurements. The exact sensitivity to patient size in automated cabin dosimetry systems, however, varies with in-built sensor positioning. The potential to extend the use of the model to investigate improved design of automated dosimetry systems is discussed.

Iron-based radiochromic systems for UV dosimetry applications

Phototherapy treatment using ultraviolet (UV) A and B light sources has long existed as a treatment option for various skin conditions. Quality control for phototherapy treatment recommended by the British Association of Dermatologists and British Photodermatology Group generally focused on instrumentation-based dosimetry measurements. The purpose of this study was to present an alternative, easily prepared dosimeter system for the measurement of UV dose and as a simple quality assurance technique for phototherapy treatments. Five different UVA-sensitive radiochromic dosimeter formulations were investigated and responded with a measurable and visible optical change both in solution and in gel form. Iron(III) reduction reaction formulations were found to be more sensitive to UVA compared to iron(II) oxidation formulations. One iron(III) reduction formulation was found to be especially promising due to its sensitivity to UVA dose, ease of production, and linear response up to a saturation point.