The University of Osaka · Medicine
Professor Yu Shimojo's research lab specializes in computational biomedical optics and laser-tissue interactions, focusing on developing in silico models to predict and optimize the safety and efficacy of laser-based medical devices. The lab pioneers computational clinical trials and simulation frameworks that integrate patient-specific tissue properties to guide clinical decision-making for picosecond and nanosecond laser treatments. Key research directions include modeling light transport, thermal diffusion, and thermal damage in biological tissues, with applications in dermatological therapeutics and regulatory science for laser device approval.
Figures are computed from collected data and may differ slightly.
The errata correct errors that appeared in Table 2 of the published article.
This computational clinical trial shows the feasibility of applying computational clinical trials for the safety evaluation of novel medical laser devices. In contrast to preclinical and clinical tests, the proposed computational method offers regulatory science for appropriately and quickly predicting and evaluating the safety of a novel laser device.
The wavelength-dependent thresholds for melanosome disruption were determined. The results of the evaluation of irradiation parameters from the threshold-based analysis provided numerical indicators for setting the clinical endpoints for 532-, 730-, 755-, 785-, and 1064-nm picosecond lasers.
Laser ablation is a minimally invasive therapeutic technique to denature tumors through coagulation and/or vaporization. Computational simulations of laser ablation can evaluate treatment outcomes quantitatively and provide numerical indices to determine treatment conditions, thus accelerating the technique's clinical application. These simulations involve calculations of light transport, thermal diffusion, and the extent of thermal damage. The optical properties of tissue, which govern light tr
Our results showed that the MDTF model can be used to evaluate nanosecond laser treatments and provide clinical guidance on fluence settings based on laser-tissue interactions in moderately pigmented skin. The in silico method can, therefore, provide a robust and quantitative retrospective evaluation of the treatment effects that accounts for variation in irradiation parameters among patients by combining the MDTF model with the in vivo optical properties of individual skin types.
The <i>Journal of Biomedical Optics</i> (JBO) is a Gold Open Access journal that publishes peer-reviewed papers on the use of novel optical systems and techniques for improved health care and biomedical research.
Background: Picosecond lasers are promising modalities for treating nevus of Ota.However, inconsistent outcomes and complication rates have hindered consensus on their clinical advantage. Objective:To evaluate the association between irradiation parameters and outcomes of picosecond versus nanosecond lasers for treating nevus of Ota through in-silico-supported meta-analysis.Methods: A meta-analysis was conducted using studies reporting clearance and complication rates after treatment with a 755-
本研究では,接触式レーザー前立腺蒸散術用の新規ファイバーであるXCAVATORファイバーによる治療の熱影響を評価するために,ブタ前立腺組織を用いた照射実験にて蒸散深さ,損傷深さ,蒸散幅を既承認のTwisterファイバーと比較することを目的とする.同一光源装置を用いて2つのファイバーから出射される波長980 nmレーザー光の照射対象面での空間分布と光拡がり角を計測し,ブタ前立腺組織を用いて蒸散深さ,損傷深さ,蒸散幅を測定した.Twisterファイバーと比較し,XCAVATORファイバーは出射光数が多く,光拡がり角で36°広範囲に光照射された.蒸散深さ,損傷深さ,蒸散幅の最大値は,それぞれXCAVATORファイバーで 1.9 ± 0.4,4.0 ± 0.7,8.1 ± 1.6 mm,Twisterファイバーで2.7 ± 1.5,4.3 ± 1.5,5.0 ± 1.5 mmであった.XCAVATORファイバーはTwisterファイバーと比較して広くて浅い蒸散をしながら同等な損傷深さとなった.以上より,XCAVATORファイバーを用いた接触式レーザー前立腺蒸散術の熱影響解析を基に,治療における
We conducted an in silico trial using computational models of laser–tissue interaction to compare 755-nm picosecond and nanosecond lasers in the treatment of nevus of Ota. By integrating melanosome-disruption threshold fluences with Monte Carlo light transport simulations, we estimated the irradiation conditions required for effective treatment and calculated thermal damage in surrounding tissue. Theoretical fluence ranges closely matched those reported in clinical studies. Picosecond lasers wer
In picosecond laser treatments for pigmented skin lesions, selective optical absorption by melanin particles packaged in cutaneous melanosomes results in producing treatment effects. The treatment effects have been numerically analyzed by simulating light propagation and thermal diffusion at a tissue scale. During picosecond laser irradiation, cutaneous melanosomes are disrupted by explosive vaporization through optical absorption by melanin particles. A multiscale modeling of picosecond laser s
Photothermal damages in laser skin treatments were evaluated computationally to analyze differences between ethnic groups. Our results revealed the seriousness of photothermal damage was varied between the ethnic groups even on the same irradiation conditions.
Our analysis revealed the influence of the optical characteristics of the lung tissue on PDT light delivery. Integration of these results with the photosensitizer dose and the degree of necrosis changes will allow us to provide more clinically relevant insight in determining PDT dosimetry.
Short-pulsed lasers can treat dermal pigmented lesions through selective photothermolysis. The irradiated light experiences multiple scattering by the skin and is absorbed by abnormal melanosomes as well as by normal blood vessels above the target. Because the fluence is extremely high, the absorbed light can cause thermal damage to the adjacent tissue components, leading to complications. To minimize radiant exposure and reduce the risk of burns, a model of the melanosome-disruption threshold f
An artificial neural network was constructed to predict optical properties of biological tissues from measured spectral values with noise. Numerical calculation revealed the improvement of estimation accuracy of the optical properties from the noised values.
The treatment effect of pigmented lesions with picosecond and nanosecond lasers is produced mainly from optical absorption by melanosomes. Differences in the treatment effect have been evaluated based on the linear absorption of local fluence. However, nonlinear absorption by melanin inside melanosomes occurs during short-pulsed laser propagation in skin tissue owing to the high-power density. Our previous study demonstrated that a nonlinear absorption model based on sequential two-photon absorp
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