PD17 From garden to GeoDome: delivering reliable daylight photodynamic therapy in a UK hospital

Abstract

Natural daylight photodynamic therapy (ndPDT) is effective and well tolerated for actinic keratoses, but UK delivery is often hindered by weather and lack of sheltered spaces. To address this, we aimed to establish a reliable, weather-protected ndPDT service using a transparent geodesic dome within a public university hospital. After confirming local commissioning of PDT, methyl aminolaevulinate and aminolaevulinic acid photosensitizers were added to the formulary. In 2022, light-level mapping identified a suitable garden site adjacent to dermatology and laser. We chose a transparent Perspex geodesic dome (GeoDomeX) with ultraviolet A/B filtration for shelter. Estate management objected on safety grounds, including risks from falling animals, emergency lighting, trip hazards and dome durability, delaying the project. An independent engineering assessment validated material safety, leading to installation in June 2025 and treatments starting in August 2025. We recorded treatment parameters (lux, temperature, duration) and clinical outcomes at 3 months. Nine patients (aged 52–86 years) received ndPDT: eight for actinic keratosis and one for field-change lesions in Muir–Torre syndrome. Seven procedures took place in the dome, and two were conducted outside on hot days. The mean light was 20 229 LUX (range 10 000–50 000). Rain occurred during six sessions, but all were completed without interruption due to the shelter. Dome temperature averaged 22.8 °C; mean lesion clearance at 3 months was 78.8%. The project cost totalled £3300. This experience shows that a geodesic dome shelter is a practical, low-cost solution for reliable PDT delivery in the NHS, supporting uninterrupted treatment and a scalable model for adoption.