Model-Based Dosimetry for Intranasal PBM with Custom LED Parameters compare MCM model to real life
Matas Jarutis
I am currently engaged in an experimental study that employs an LED with a wavelength of 808nm, delivering an output of 50mW, which can be pulsed at 10Hz or operated in continuous wave (CW) mode. We utilize nasal-held probes for intranasal illumination, targeting the nostril position, in an attempt to understand its penetration on pig brain tissue. Our setup includes measurements using an Ocean Optics spectrometer to record the results of our intervention.
We are keen to accurately simulate our parameters to validate and compare them with the findings in real-life experimental arrangements, as demonstrated in your study using the Colin27 atlas model leads us to believe this is the best option for us as well. To this end, I would greatly appreciate it if you could provide guidance on incorporating our power parameters into the model-based dosimetry study. Specifically, we are looking to:
1. Understand the necessary steps to simulate our specific LED power and pulsing parameters within the previous work framework.
2. Learn how to run the simulation explained that accurately represent intranasal illumination placement.
Thank you for considering my request. I look forward to the possibility of further correspondence or collaboration.
Kind regards,
Qianqian Fang
Dear Dr. Qianqian Fang,
I am writing to seek your expertise regarding a study you authored, "Selective photobiomodulation for emotion regulation: model-based dosimetry study," which was published online on February 7, 2019.
I am currently engaged in an experimental study that employs an LED with a wavelength of 808nm, delivering an output of 50mW, which can be pulsed at 10Hz or operated in continuous wave (CW) mode. We utilize nasal-held probes for intranasal illumination, targeting the nostril position, in an attempt to understand its penetration on pig brain tissue. Our setup includes measurements using an Ocean Optics spectrometer to record the results of our intervention.
We are keen to accurately simulate our parameters to validate and compare them with the findings in real-life experimental arrangements, as demonstrated in your study using the Colin27 atlas model leads us to believe this is the best option for us as well. To this end, I would greatly appreciate it if you could provide guidance on incorporating our power parameters into the model-based dosimetry study. Specifically, we are looking to:
1. Understand the necessary steps to simulate our specific LED power and pulsing parameters within the previous work framework.
the approach that mcx currently uses to handle source power and source waveforms is strictly based on the linear property of the RTE to the source term - i.e., mcx only obtains the impulse response function (IRF(r,t)) by simulating a Dirac-delta function as the source, and assumes
1. a source with an arbitrary power A that is not unitary will yield a response of A*IRF(r,t), and
2. a source with an arbitrary waveform S(t) will result in a response conv(S(t), IRF(r,t)), where conv() is the temporal convolution between S and IRF
I am aware that in PMB treatment, pulsed waveforms are often used
and are known to have different effectiveness compared to CW
sources. Unfortunately, from mcx's simulation perspective, if your
CW and pulsed waveform delivered the same total power (after
integration), the total deposit energy will be exactly identical
based on the above linear assumption - in other words, mcx won't
be able to explain such therapeutic difference purely from a light
dosage perspective - it might be caused chemically or thermally,
but I will leave this to PBM researchers.
2. Learn how to run the simulation explained that accurately represent intranasal illumination placement.
you will need to have an anatomical scan of the pig model, such
as a CT or MRI, segment into tissue regions, extract he nasal
cavity surface, and then you can set your source position based on
the mesh or segmented volume. For LED emission profile, a recently
implemented angular launch distribution feature could be helpful,
although not critical - a pencil beam or angular Gaussian
(zgaussian) source could also lead to reasonable results
3. Compare our experimental outcomes with model-predicted results to discern the variations and potential implications for human clinical applications.
this will be absolutely a meaningful work and let me know if I can explain anything in addition. one thing to keep in mind is that simulation will always involve simplifications and approximations. to exactly match in absolute scale will be hard, but you can match in relative values or scales. the choice of optical properties for different tissue types (skin, muscle, fat, bones) and the assumption of tissue layer thicknesses could always impact your absolute values (energy deposition etc), but relative ratios between different wavelengths, placement locations, angles, or LED profiles could still be meaningful.
Qianqian
Thank you for considering my request. I look forward to the possibility of further correspondence or collaboration.
Kind regards,
Matas
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Matas Jarutis
Thank you for your prompt and informative response to my queries. Your detailed explanations have helped me understand better.
To facilitate a deeper understanding and help validate our study's next steps, could you please share the experimental code/calculations used in your study? Specifically, the implementations related to the Colin27 atlas model within the mcx space would be of great interest in trying to replace the results you achieved If you are willing, please send the relevant files or details to my private email at matasa...@gmail.com.
I look forward to any additional guidance you offer, I am continuing with the practical steps since this is currently taking most of my time the MCM model would be the cherry on the top for validation and is in very early stages of understanding.
Warm regards, Matas Jarutis