Physiological considerations acting on triplet oxygen for explicit dosimetry in photodynamic therapy

Sánchez, Víctor; Romero, María Paulina; Pratavieira, Sebastião; Vera, César Costa

doi:10.1016/j.pdpdt.2017.07.008

Cited by 9 publications

(6 citation statements)

References 25 publications

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“…This would require measurements of dynamic drug and oxygen concentrations that entered into theoretical models. 11,12,20 Extensive in vivo studies and very promising results on this topic have been published. [11][12][13] For example, using an explicit model, one study calculated 1 O 2 concentrations at different radial distances from the excited benzoporphyrin derivative monoacid ring A (BPD).…”

Section: Introductionmentioning

confidence: 99%

Multispectral singlet oxygen and photosensitizer luminescence dosimeter for continuous photodynamic therapy dose assessment during treatment

et al. 2020

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Significance: Photodynamic therapy (PDT) involves complex light-drug-pathophysiology interactions that can be affected by multiple parameters and often leads to large variations in treatment outcome from patient to patient. Direct PDT dosimetry technologies have been sought to optimize the control variables (e.g., light dose, drug administration, tissue oxygenation, and patient conditioning) for best patient outcomes. In comparison, singlet oxygen (1 O 2) dosimetry has been tested in various forms to provide an accurate and perhaps comprehensive prediction of the treatment efficacy. Aim: We discuss an advanced version of this approach provided by a noninvasive, continuous wave dosimeter that can measure near-infrared spectrally resolved luminescence of both photosensitizer (PS) and 1 O 2 generated during PDT cancer treatment. Approach: This dosimetry technology uses an amplified, high quantum efficiency InGaAs detector with spectroscopic decomposition during the light treatment to continuously extract the maximum signal of 1 O 2 phosphorescence while suppressing the strong PS luminescence background by spectrally fitting the data points across nine narrow band wavelengths. 1 O 2 and PS luminescence signals were measured in vivo in FaDu xenograft tumors grown in mice during PDT treatment using Verteporfin as the PS and a continuous laser treatment at 690 nm wavelength. Results: A cohort of 19 mice was used and observations indicate that the tumor growth rate inhibition showed a stronger correlation with 1 O 2 than with just the PS signal. Conclusions: These results suggest that 1 O 2 measurement may be a more direct dosimeter of PDT damage, and it has potential value as a definitive diagnostic for PDT treatment, especially with spectral separation of the background luminescence and online estimation of the PS concentration.

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Section: Introductionmentioning

confidence: 99%

Multispectral singlet oxygen and photosensitizer luminescence dosimeter for continuous photodynamic therapy dose assessment during treatment

et al. 2020

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“…In order to model the photo-physical-chemical reactions in PDT is common to use these differential equations to describe PS transitions, oxygen interactions and cell kill. [16][17][18]28 The term with positive or negative sign means respectively that, the rate of the molar concentration increase or decrease by some process of energy absorption or release.…”

Section: Typical Mathematical Model For Pdtmentioning

confidence: 99%

“…[12][13][14][15] Nowadays, theoretical and simulation researches have been developed to estimate the efficiency of PDT. [16][17][18] In this study, the concept of the photon dose is addressed. We assumed that the total photodynamic effect is the sum of fractionated effects.…”

Section: Introductionmentioning

confidence: 99%

Theoretical evaluation of the light distribution and PDT dose for a multi-wavelength light source

Guachamin¹

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The broad absorption spectrum of Protoporphyrin IX (PpIX) allows being activated by a source with an emission spectrum in the visible region. Also, PpIX can be activated simultaneously by two or more sources whose emission spectrum overlaps with its absorption spectrum. Sources with a wide spectrum of illumination, such as lamps and Sun, have a different light-tissue interaction, and the constant monitoring of the dose of light and the total damage caused by photodynamic therapy (PDT) becomes difficult. The main objectives of this study were to simulate the distribution of light in the tissue for a multiwavelength source and determine the total theoretical photodynamic dose. This study is composed of three parts. First, photobleaching experiments of PpIX using different light sources and the development of a mathematical model was used to explain the change in PpIX concentration. Second, Monte Carlo simulation using MCX (Monte Carlo eXtreme) was performed to know the light distribution through in a human skin model. Finally, the theoretical photodynamic dose was determined using the two steps mentioned previously. The experimental results show that the decrease in the concentration of PpIX is mainly dependent on the dose of photons absorbed. Therefore, for a multi-wavelength source, the total damage is calculated by partial damages caused by each wavelength that active the PpIX. The simulation of the light distribution in the human skin phantom demonstrated that the energy fluence rate decrease as a function of the depth. The mathematical model estimates that the efficacy of PDT, where it is guaranteed there is necrosis, has a diameter and depth of about 0.3 and 0.2 mm respectively. This model can be expanded to other biological media, other photosensitizers and even to any source of illumination.

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“…42 Alternatively, 1 P S * may undergo an intersystem crossing (ISC), to form a more stable triplet state T changing the spin orientation of one electron getting two electrons with equal spins, a total spin of f Fluorescence is a form of luminescence (light emission of a molecule that has absorbed light or other electromagnetic radiation) whose typical lifetimes are of the order of nanoseconds. Source: SANCHEZ et al 41 S=1 and a spin multiplicity of 3, as follows:…”

Section: Photophysics and Photochemistry Process In Pdtmentioning

confidence: 99%

Analysis of sono-photodynamic effects with PpIX - >i<in Vitro>/i< and >i<in vivo>/i< studies

Ayala¹

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stormy path of life, giving me the opportunity day by day to grow as a person, as a professional, to enjoy life and give back to it giving my best. Thank you for, without a doubt, the most precious treasure I have: my beautiful family. I am very thankful to my parents Neil and Redina, for the love and education they gave me, for the effort they made so that nothing ever lacks me, and I could continue chasing my goals and dreams. Thank you so much for always trusting me, making me feel so safe and comforted in moments of weakness. I thank my sisters, Emily and Tamara, my two little princesses whom I adore and who without knowing it, turned my troubled days into the most fun and endearing. I would also like to thank my grandparents, uncles, cousins and nephews, both paternal and maternal ones, whose messages during this time outside my country helped me to feel not that far from home.

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Physiological considerations acting on triplet oxygen for explicit dosimetry in photodynamic therapy

Cited by 9 publications

References 25 publications

Multispectral singlet oxygen and photosensitizer luminescence dosimeter for continuous photodynamic therapy dose assessment during treatment

Multispectral singlet oxygen and photosensitizer luminescence dosimeter for continuous photodynamic therapy dose assessment during treatment

Theoretical evaluation of the light distribution and PDT dose for a multi-wavelength light source

Analysis of sono-photodynamic effects with PpIX - >i<in Vitro>/i< and >i<in vivo>/i< studies

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