Quantifying the radiant exposure and effective dose in patients treated for actinic keratoses with topical photodynamic therapy using daylight and LED white light

Simulating PDT of port-wine stains in the in vivo chicken wattle model using Hemoporfin and radiation at 532 nm: Comparison of a LED and a laser source

Port-wine stain (PWS) birthmarks are congenital capillary malformations occurring in 0.3 %∼0.5 % of newborns. Hemoporfin-mediated vascular-acting photodynamic therapy (Hemoporfin PDT) is an emerging option for treating PWS. This in vivo study aimed to compare laser and light-emitting diodes (LED) as light source for Hemoporfin PDT. Chicken wattles were used as the animal model. Color and histopathological changes were evaluated after combining Hemoporfin with KTP laser or LED light source of 532 nm at the same doses. Both PDT approaches could induce significant vascular injury and color bleaching. Although the use of the laser resulted in a greater vascular clearance, the LED showed more uniform distribution both in the beam profiles and tissue reaction and exhibited better safety. This in vivo study suggests that the LED is a favorable choice for larger PWS lesion.

Measurements of illuminance in simulated daylight photodynamic therapy

BACKGROUND

Simulated daylight photodynamic therapy (SDL-PDT) is a new treatment alternative for actinic keratosis. The aim of this study was to show how the illuminance that reaches the target skin area during SDL-PDT depends on the spatial positioning of the patient.

METHODS

In this technical validation study, illuminance from the SDL-PDT system IndoorLux© was measured at different angles, directions, and distances from the light sources corresponding to potential target skin areas. Using two different photometers, data from 63 measuring points at seven specific distances from the ceiling were collected at 0°, 45°, and 90° angles, respectively. Illuminance levels ≥12,000 lux were regarded as adequate. Hotspots were defined as adequate measurements in all directions at a specific measuring point at distances of 1.3, 1.5, and 1.8 m from the light sources (i.e., the most common patient treatment positions).

RESULTS

Adequate illuminance levels were more common with photometer 1 (73%) than photometer 2 (57%). Almost all illuminance levels were adequate at a 0° angle with both photometers. Adequate illuminance levels were observed at 82-93% of the measuring points at a 45° angle and 22-47% at a 90° angle. Hotspots were registered with both photometers at all measuring points at 0°; 59-79% of the measuring points at 45°; and 0-21% at 90°.

CONCLUSION

Patient positioning is important during SDL-PDT. Adequate illuminance is achieved if target skin areas are positioned at 0°-45° angles relative to the light sources, but not at 90° angles.

Theoretical design of an absorption hologram-based sensor for dose quantification in daylight photodynamic therapy

Daylight photodynamic therapy (D-PDT) is an effective and almost painless treatment for many skin conditions, where successful treatment relies on daylight activation of a topical photosensitizer. Optimization of D-PDT requires accurate assessment of light dose received. There is a requirement for a small-area sensor that can be placed adjacent to the treatment site to facilitate accurate dose quantification. Here, a novel, to the best of our knowledge, configuration for a D-PDT dose sensor, consisting of a holographic absorption grating fabricated in a photosensitive film, is presented. Theoretical modeling of the sensor's response (i.e., change in grating diffraction efficiency due to change in grating absorption modulation, α₁, on exposure to daylight) was conducted using Kogelnik's coupled-wave theory. The influence of the different grating parameters (initial film absorption, thickness, spatial frequency, and reconstruction wavelength) on the sensor response was examined and revealed that the initial absorption and grating thickness values have a large impact on both the magnitude and rate of the D-PDT sensor response. The optimum design for an absorption grating-based D-PDT sensor is described.

Clinical evaluation of a short illumination duration (1 hour) when performing photodynamic therapy of actinic keratosis using the Dermaris light source

BACKGROUND

Photodynamic therapy (PDT) using daylight as the photoactivating light source (DL-PDT) is an effective treatment for actinic keratosis (AK). Among the artificial daylight sources, the Dermaris (Surgiris, Croix, France) is specially designed for SDL-PDT (simulated daylight PDT) of AK. To perform the PDT session, a long duration (2.5 h) and low-intensity light exposure (2.9 mw/cm²) is used. This long duration is considered as a major limitation by both the patient and the dermatologist.

OBJECTIVES

The paper aims to report the clinical outcomes of SDL-PDT using the Dermaris in patients treated for AK lesions of the scalp at our medical dermatology center using only one hour low-intensity light exposure.

METHODS

Thirty patients (19 males, 11 females), mean age: 72.8 ± 9.3, with phototype 1 (11 patients), with phototype 2(17 patients) and phototype 3 (2 patients), with grade I-II AK of the scalp were treated with a drug-light interval (DLI) of 10 min and a light exposure of 1 h. The cure rate of AK lesions at six months after the treatment was determined. Erythema, crusts, discomfort and during or/and post the treatment were also evaluated.

RESULTS

In total, 293 AK were treated. Six months following treatment, the cure rate of patients was 93%. Pain score reported after the first PDT session was from 0 to 1 on a visual analogue scale (VAS) ranging from 0 to 10. Erythema was observed in 28 patients and lasted 3 days, crusts were seen in 19 patients. Discomfort was as mild or less in more than 97% of patients.

CONCLUSIONS

the shortening of the exposure time to one hour does not modify the efficacy of the SDL-PDT using the Dermaris. This observation is in agreement with recent published data demonstrating that PDT can be performed successfully with half the illumination time used in daylight PDT today. Besides, this clinical study confirmed that SDL-PDT is an effective and nearly painless treatment with minimal side effects for patients with AK lesions of the scalp.

An open-label prospective study to assess short incubation time white LED light photodynamic therapy in the treatment of superficial basal cell carcinoma

Artificial white LED light photodynamic therapy (awl-PDT) is an effective, pain-free treatment for actinic keratosis. The efficacy of awl-PDT in the treatment of superficial basal cell carcinoma (sBCC) has not been assessed. Patients with histologically confirmed sBCC underwent two treatments of awl-PDT 1 week apart. Lesions were incubated with methyl 5-aminolaevulinic acid for 30 min and then illuminated using the Maquet Power LED 500 theatre light (405-800nm, 140 000 lux) to deliver an equivalent red light dose of 75 J/cm² at a rate of 55 mW/cm² . Pain was measured using a visual analogue scale during treatment. Clinical response was assessed at day 28. Follow-up continued 3 months for 1 year. Cosmetic outcome was assessed at 3 months and 1 year. Twenty-eight patients with 36 lesions and a mean age of 63.64 (SD 2.62) were recruited. The median lesion size was 15 mm (IQR 8.75). The response rate at day 28 was 100%. Recurrence rates were 3/36 (8.3%) at 3 months, 6/36 (16.7%) at 6 months, 10/36 (27.8%) at 9 months and 11/36 (30.6%) at 1 year. Median pain scores were 0/100 (IQR 0) and 0/100 (IQR 5) during treatments one and two, respectively. Cosmetic outcome was excellent or good in the majority of cases. Although initially effective for sBCC at 28 days, 30.6% of lesions recurred 1 year after awl-PDT. Pain scores were negligible, and the cosmetic outcome was favourable. Further head-to-head studies with optimised protocols are required to determine if awl-PDT has a role in the treatment of sBCC.

Preparation, stimuli-response performance of HPC-PMAA/PpIX nanogels and their application in photodynamic therapy

In the present study, a novel nanogel of HPC-PMAA/PpIX with thermo- and pH sensitive performance and its application in cancer photodynamic therapy is reported. HPC-PMAA/PpIX nanogels were prepared by free radical polymerization method with HPC as template, hydroxypropyl cellulose (HPC), methyl acrylic acid (MAA), protoporphyrin IX (PpIX) and N,N'-methylene bisacrylamide (BIS) as raw materials. The as-prepared nanogels were characterized by Fourier transform infrared (FTIR), photoluminescence (PL) and UV-visible spectrophotometer (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). PL and UV-vis spectra demonstrate that PpIX is incorporated into HPC-PMAA by covalent bonds, and its aggregation is prevented. Moreover, the as-prepared nanogels can be dispersed in water over 1 week, significant singlet oxygen can be produced under irradiation of laser. With tumor cell of HepG2 as model cell, the nanogels are biocompatible with cell viability of >85% even at high concentrations of the PpIX in vitro. In addition, the HPC-PMAA/PpIX nanogels show photo-dependent toxicity in the concentration range of 10 µg/mL of PpIX, suggesting that HPC-PMAA/PpIX nanogels have potential for the treatment of photodynamic therapy (PDT).

Irradiance uniformity optimization for a photodynamic therapy treatment device with 3D scanner

SIGNIFICANCE

The light dose in photodynamic therapy (PDT) has a considerable influence on its treatment effect, and irradiance uniformity is an issue of much concern for researchers. However, achieving intelligent and personalized dosimetry adjustments remains a challenge for current PDT instruments.

AIM

To meet the requirements of intelligent and personalized dosimetry adjustments for the light dose on an irregular surface, a new PDT device with its optimal control method is proposed.

APPROACH

This research introduces a new PDT device that includes a 3D scanner, a light-emitting diode (LED) array, and a computer. The 3D scanner is proposed to generate the point cloud of the lesion and the LED array light source, and obtain the relative position and rotation parameters between them. Then, an image segmentation algorithm is used to segment the lesion point cloud into several cluster regions. Last, the current of each LED unit is adjusted separately to achieve the expected irradiance on each cluster.

RESULTS

Compared with the general light source, the optimized light source increases the effective irradiance area by 9% to 15% and improves its uniformity by ∼9  %   on a human port-wine stain head model.

CONCLUSIONS

The device and its optimal method may be used for optimizing the light dosimetry to realize intelligent and personalized treatment.

Global verification of a model for determining daylight photodynamic therapy dose

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). This model has been verified against spectral irradiance data from the UK, however the accuracy of the model has not been determined outside the UK. In this work, we test the O'Mahoney model against spectral irradiance measurements from several global locations to within bounds of a median deviation of ±10 %. The median percentage deviations are shown to be independent of location latitude and longitude. The model can be used confidently to determine PpIX-effective irradiance from illuminance measurements irrespective of location and can be widely implemented as an effective and low-cost means of accurately measuring effective light exposure for this important treatment.

SmartPDT®: Smartphone enabled real-time dosimetry via satellite observation for daylight photodynamic therapy

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.

METHODS

SmartPDT® is a smartphone-based application and web-portal, developed by siHealth Ltd, enabling remote delivery of dPDT. It uses satellite imagery and computational algorithms to provide real-time determination of exposure to PpIX-effective solar radiation ("light dose"). The application also provides forecast of expected radiant exposures for 24- and 48-hs prior to the treatment period. Validation of the real-time and forecasted radiant exposure algorithms was performed against direct ground-based measurement under all weather conditions in Chilton, UK.

RESULTS

Agreement between direct ground measurements and satellite-determined radiant exposure for 2-h treatment was excellent at -0.1 % ± 5.1 % (mean ± standard deviation). There was also excellent agreement between weather forecasted radiant exposure and ground measurement, 1.8 % ± 17.7 % at 24-hs and 1.6 % ± 25.2 % at 48-hs. Relative Root Mean Square of the Error (RMSE_r) demonstrated that agreement improved as time to treatment reduced (RMSE_r = 22.5 % (48 -hs), 11.2 % (24-hs), 5.2 % (real-time)).

CONCLUSION

Agreement between satellite-determined, weather-forecasted and ground-measured radiant exposure was better than any existing published literature for dPDT. The SmartPDT® application and web-portal has excellent potential to assist with remote delivery of dPDT, an important factor in reducing risk in an elderly patient population during the Covid-19 pandemic.

Measuring Daylight: A Review of Dosimetry in Daylight Photodynamic Therapy

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. Furthermore, for the majority of practitioners who do not carry out any formal dosimetry and for the patients receiving DPDT, building confidence in the evidence supporting this important treatment option is of key importance. This review seeks to clarify the methodology of DPDT and discusses the literature relating to DPDT dosimetry.

Preclinical Evaluation of White Led-Activated Non-porphyrinic Photosensitizer OR141 in 3D Tumor Spheroids and Mouse Skin Lesions

Photodynamic therapy (PDT) is used to treat malignancies and precancerous lesions. Near-infrared light delivered by lasers was thought for a while to be the most appropriate option to activate photosensitizers, mostly porphyrins, in the depth of the diseased tissues. More recently, however, several advantages including low cost and reduced adverse effects led to consider light emitting diodes (LED) and even daylight as an alternative to use PDT to treat accessible lesions. In this study we examined the capacity of OR141, a recently identified non-porphyrin photosensitizer (PS), to exert significant cytotoxic effects in various models of skin lesions and tumors upon white light activation. Using different cancer cell lines, we first identified LED lamp as a particularly suited source of light to maximize anti-proliferative effects of OR141. We then documented that OR141 diffusion and light penetration into tumor spheroids both reached thresholds compatible with the induction of cell death deep inside these 3D culture models. We further identified Arlasove as a clinically suitable solvent for OR141 that we documented by using Franz cells to support significant absorption of the PS through human skin. Finally, using topical but also systemic administration, we validated growth inhibitory effects of LED-activated OR141 in mouse skin tumor xenograft and precancerous lesions models. Altogether these results open clinical perspectives for the use of OR141 as an attractive PS to treat superficial skin malignant and non-malignant lesions using affordable LED lamp for photoactivation.

A novel light source with tuneable uniformity of light distribution for artificial daylight photodynamic therapy

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. A novel light source is developed with tuneable direction of light emission in order to meet this challenge.

METHODS

Wavelength composition of the novel light source is controlled such that the protoporphyrin-IX (PpIX) weighted spectra of both the light source and daylight match. The uniformity of the light distribution is characterised on a flat surface, a model head and a model leg. For context, a typical conventional PDT light source is also characterised. Additionally, the wavelength uniformity across the treatment site is characterised.

RESULTS

The PpIX-weighted spectrum of the novel light source matches the PpIX-weighted daylight spectrum, with irradiance values within the bounds for effective dPDT. By tuning the direction of light emission, improvements are seen in the uniformity across large anatomical surfaces. Wavelength uniformity is discussed.

CONCLUSIONS

We have developed a light source that addresses the challenges in uniform, multiwavelength light distribution for large area artificial dPDT across curved anatomical surfaces.