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Protonterapia en la Comunidad Valenciana. ¿Cuándo y cómo?

• Francisco Javier Celada Álvarez (Hospital Universitario y Politécnico La Fe)

Hacia una integración eficiente de tecnologías de imagen y terapias por radiación en la práctica clínica

• Montserrat Carles Farina (Hospital Universitario La Fe)

Networking

Expanding the Toolbox for Theranostics: From Chemical Probes to Reporter Genes

• Susana Carregal Romero (CIC biomaGUNE)

Range Verification in Particle Therapy for Preclinical Research Using PET

• Giulio Lovatti (Ludwig Maximilian University of Munich, Department of Physics )

Bridging physics, biology, and clinic: a forward view of UHDR radiotherapy and VHEE FLASH

• Costanza Panaino (University of Manchester)

Poster: EFECTO ESPECTRAL DE FILTRO SELECTIVO: CARACTERIZACIÓN COMPARATIVA ENTRE EMISIÓN DIGITAL Y REFLECTANCIA DEL PAPEL (Monitoring)

• CARMEN MARTIN ARANDA (UNIVERSIDAD COMPLUTENSE DE MADRID)

El uso de dispositivos digitales ha incrementado la exposición a fuentes de luz artificial con espectros distintos a los medios impresos. Muchas pantallas emiten un pico en la región azul del espectro visible(440-460 nm), inexistente en el papel bajo iluminación normal(1). La luz azul, por su mayor energía, puede afectar a la fatiga ocular, la supresión de melatonina y otros procesos biológicos(2). Para reducirla se emplean filtros de absorbancia selectiva(3). Este trabajo compara la emisión espectral de una pantalla digital con y sin filtro frente a la reflectancia del papel. Para la caracterización espectral del papel, se dividió un folio en 9 áreas y se registraron mediciones espectrofotométricas en cada una, bajo una iluminación de 16.8cd/m² medida con luxómetro. Los valores obtenidos se promediaron y se analizaron las longitudes de onda de 440 y 470nm principalmente. De la misma forma, la pantalla de un iPhone 13 se dividió en 9 áreas, realizándose mediciones en cada una con y sin filtro selectivo, y con el brillo ajustado a tres niveles(mínimo, medio y máximo). Los datos resultantes se promediaron para las mismas longitudes de onda de interés. Los resultados mostraron que la reflectancia del papel se mantuvo baja y estable en ambas longitudes de onda, con una intensidad ≈700 cuentas, en contraste con la pantalla digital, cuya intensidad de emisión se incrementó notablemente, especialmente en 470nm, alcanzando valores superiores a 10.000 cuentas con brillo máximo. La aplicación del filtro de absorbancia selectiva redujo la intensidad emitida en esta banda, con descensos de alrededor del 10–20% según el nivel de brillo, mientras que en 440nm las diferencias fueron menores. Los resultados evidencian diferencia entre la emisión espectral de las pantallas digitales y la reflectancia del papel en la región de 460-470nm, lo que refuerza la importancia de implementar medidas que limiten la exposición a esta franja del espectro durante el uso prolongado de pantallas, en particular cuando se utilizan con niveles altos de brillo.

Poster: The Physics of the Pupil: Age and Ethnicity Effects in Static Mesopic Conditions (Monitoring)

• CELIA SANCHEZ RAMOS (Universidad Complutense de Madrid)
• VANESA BLAZQUEZ SANCHEZ (Universidad Complutense de Madrid)
• MAME DIATOU TOURE SARR (UNIVERSIDAD COMPLUTENSE DE MADRID)

Purpose: This study aimed to compare static pupillometry under mesopic conditions between European and African populations, given the limited data directly contrasting pupillary dimensions across ethnic groups. Characterizing pupil diameter is relevant in detecting ocular alterations, particularly in a multicultural context. While age-related pupillary changes are well documented in Caucasian and Asian populations, evidence in Africans is scarce. This work establishes initial reference values for the Senegalese population as a starting point for further studies. Settings: Data were collected at three locations: Caucasian participants at the Optometry Clinic of the Complutense University of Madrid; Afro-Europeans (AFE, African origin but lifelong residents in Europe) in the Lavapiés district of Madrid; and Africans (AFR) at Abass Ndao Hospital, Dakar. The study complied with the Declaration of Helsinki. Methods: Analytical cross-sectional observational study with 88 CAU, 129 AFR, and 78 AFE, aged 18–75 years. All provided written informed consent. Static pupillometry was measured with the Nidek HandyRef-K portable autorefractor-keratometer; five measurements per participant by the same examiner. Results: • Ethnic comparison: mean pupil diameters: CAU 4.67 ± 0.7 mm; AFR 5.11 ± 1.0 mm; AFE 4.44 ± 1.0 mm (p < 0.001). • Age comparison: In CAU, no significant differences among young, adult, and >45 years groups (p > 0.05). Both AFR and AFE showed significant differences (p < 0.05), with younger participants having the largest diameters, followed by adults, and the smallest values in those >45 years. Conclusions: Africans showed larger pupil diameters compared to Caucasians and Afro-Europeans, between whom no significant differences were observed. Age had no effect in Caucasians, while both Africans and Afro-Europeans showed decreasing diameters with age. These findings provide reference data for Senegalese populations and support further cross-ethnic research. Key words: Axial length, Race, Sex, Ocular Biometry, Africans, Caucasians References: 1. Birren JE, Casperson RC, Botwinick J. Age changes in pupil size. Journal of Gerontology. 1950;5(3):216-21. 2. Winn B, Whitaker D, Elliott DB, Phillips NJ. Factors affecting light-adapted pupil size in normal human subjects. Investigative ophthalmology & visual science. 1994;35(3):1132-7 3. Tekin K, Sekeroglu MA, Kiziltoprak H, Doguizi S, Inanc M, Yilmazbas P. Static and dynamic pupillometry data of healthy individuals. Clin Exp Optom. 2018 Sep;101(5):659-665. doi: 10.1111/cxo.12659. Epub 2018 Jan 21. PMID: 2935607

Asamblea

PTCOG 2025 award: Mapping intratumoral heterogeneity through PET-derived washout and deep learning after proton therapy (Positron Emission Tomography)

• Pablo Cabrales (Grupo de Física Nuclear and IPARCOS, Universidad Complutense de Madrid)

The distribution of produced isotopes during proton therapy can be imaged with Positron Emission Tomography (PET) to verify dose delivery. However, biological washout, driven by tissue-dependent processes such as perfusion and cellular metabolism, reduces PET signal-to-noise ratio (SNR) and limits quantitative analysis. In this work, we propose an uncertainty-aware deep learning framework to improve the estimation of washout parameters in post-proton therapy PET, not only enabling accurate correction for washout effects, but also mapping intratumoral heterogeneity as a surrogate marker of tumor status and treatment response. We trained the models on Monte Carlo-simulated data from eight head-and-neck cancer patients, and tested them on four additional head-and-neck and one liver patient. Each patient was represented by 75 digital twins with distinct tumoral washout dynamics and imaged 15 minutes after treatment, when slow washout components dominate. We also introduced "washed-out" maps, quantifying the contribution of medium and fast washout components to the loss in activity between the end of treatment and the start of PET imaging. Trained models significantly improved resolution and accuracy, reducing average absolute errors by 60% and 28% for washout rate and washed-out maps, respectively. For intratumoral regions as small as 5 mL, errors predominantly fell below thresholds for differentiating vascular status, and the models generalized across anatomical areas and acquisition delays. This study shows the potential of deep learning in post-proton therapy PET to non-invasively map washout kinetics and reveal intratumoral heterogeneity, supporting dose verification, tumor characterization, and treatment personalization. The framework is currently being validated using phantom experiments at Clínica Universidad de Navarra, Spain, and clinical data at Massachusetts General Hospital, USA. The implementation code is available at https://github.com/pcabrales/ppw.

Production of medical radioisotopes using laser-plasma accelerators (Positron Emission Tomography)

• Jose Benlliure (IFIC (CSIC - Universitat de Valencia))

The development of novel medical imaging techniques such as PET (Positron Emission Tomography) and SPECT (Single-Photon Emission Computed Tomography) has increased the demand for nuclear radioisotopes in medical diagnostics. Currently, the production of radioisotopes for medical imaging and treatment is primarily carried out using conventional accelerators (cyclotrons) and dedicated nuclear reactors. In the case of positron emitters used in PET imaging, the current approach involves producing positron radiotracers at large facilities that are responsible for supplying radioisotopes on a regional or national scale. Due to the cost of production centres, accelerators, radio-pharmacies and, in particular, radiation shielding, the economic viability of these centres depends on mass-producing single doses for distribution to as many hospitals and research centres as possible. As a result of this regional scope, commercial production of PET radioisotopes is mainly limited to 18F, which has a half-life of around 110 minutes and can therefore endure the time required for production, post-processing and distribution. Consequently, the production of a limited number of doses of shorter-lived radioisotopes, such as 11C (with a half-life of ~20 min), 13N (with a half-life of ~10 min) and 15O (with a half-life of ~2 min), is generally beyond the capabilities of these facilities. Over the last few decades, the use of ultra-short, ultra-intense lasers for radioisotope production has been proposed as a cost-efficient alternative for the on-demand production of single doses of short-lived radioisotopes. Through the target normal sheath acceleration (TNSA) mechanism, ultra-intense laser pulses (I > 10¹⁸ W/cm²) impinging on a micrometre-thick target can result in the acceleration of ion beams to energies of several tens of MeV. The nature and properties of this laser-induced acceleration process overcome the main constraint of conventional production facilities. As the laser-target interaction occurs over a micrometre-scale distance, the shielding requirements are much lower than for nuclear reactors or accelerators. Thus, laser systems of this class become significantly more affordable for hospitals, clinics and research centres. These facilities could then produce radioisotopes on demand and explore shorter-lived emitters that are not currently produced. In this talk, we will present our key accomplishments in this area. In particular, we will demonstrate our ability to produce 11C using the 11B(p,n)11C reaction with activation levels exceeding 4 MBq in a recent experiment conducted at CLPU in Salamanca.

Closing session

• Gabriela Llosá (IFIC (CSIC-UV))