Biomedical Optics 6 MCQ

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Questions and Answers

Which year did Darafsheh publish regarding light sources and dosimetry techniques for photodynamic therapy?

2020 (correct)

2021

2019

2018

What volume number is associated with the photodynamic therapy article by Darafsheh?

96 (correct)

What is the primary focus of the article authored by Makropoulou and colleagues?

Solar energy utilization

Chemical engineering applications

Light sources and dosimetry techniques (correct)

Environmental impacts of photobiology

Which of the following elements is NOT mentioned in the context of the articles provided?

Radiation safety Signup and view all the answers

On what page range does Darafsheh's article appear?

280-290 Signup and view all the answers

What role primarily ensures the safe and effective use of lasers in a biomedical setting?

Medical Laser Safety Officer (MLSO) Signup and view all the answers

Which of the following is NOT a responsibility of the Laser Safety Officer?

Designing laser control systems Signup and view all the answers

Who is primarily responsible for ensuring the safety of healthcare personnel and patients in laser applications?

Medical Laser Safety Officer (MLSO) Signup and view all the answers

What aspect of laser use does a Laser Safety Officer particularly focus on?

Safety regulations and compliance Signup and view all the answers

Which statement correctly reflects the importance of a Medical Laser Safety Officer in a healthcare setting?

They play a critical role in both patient and staff safety. Signup and view all the answers

In a biomedical context, which property of laser radiation is crucial for effective safety management?

Wavelength and intensity Signup and view all the answers

What is a significant consequence of improper laser use in a healthcare setting?

Patient and staff safety risks Signup and view all the answers

What is the primary responsibility of the LSO/MLSO?

To ensure laser hazard standards are followed Signup and view all the answers

Which of the following statements is true regarding the LSO/MLSO's qualifications?

They could also hold a Medical Physicist’s license Signup and view all the answers

In the context of laser safety, what does LSO stand for?

Laser Safety Officer Signup and view all the answers

Which of the following is NOT a duty of the LSO/MLSO?

Creating laser technology Signup and view all the answers

What aspect of laser operations may the LSO/MLSO oversee?

Compliance with hazard controls Signup and view all the answers

Which professional role might overlap with that of the LSO/MLSO?

Medical Physicist Signup and view all the answers

Which of the following tasks is essential for ensuring laser safety?

Monitoring compliance with safety standards Signup and view all the answers

What is the ultimate goal of the LSO/MLSO in their role?

To direct safe laser use and compliance Signup and view all the answers

Which competency is not required for the role of an LSO/MLSO?

Licensure as a Medical Physicist Signup and view all the answers

What initiates photochemical processes in biological tissues?

Molecular photo-excitation due to photon absorption Signup and view all the answers

Which statement correctly describes a consequence of photochemical effects?

They can initiate subsequent biochemical reactions. Signup and view all the answers

Which phenomenon is most directly involved in the induction of photochemical effects in tissues?

Molecular photo-excitation Signup and view all the answers

In photochemical interactions, what is the primary role of photons?

To enable molecular transitions between energy states Signup and view all the answers

What is NOT a characteristic of photochemical processes?

They always produce heat as a byproduct Signup and view all the answers

What determines the effectiveness of photochemical effects in biological tissues?

The wavelength and energy of the absorbed photons Signup and view all the answers

Which mechanism is primarily responsible for initiating photochemical reactions?

Absorption of photons leading to molecular transitions Signup and view all the answers

What is a common misconception about photochemical processes?

They can occur only with high-energy UV light Signup and view all the answers

What role does molecular photo-excitation play in biological systems?

It initiates chemical changes in target molecules Signup and view all the answers

Study Notes

Photodynamic Therapy (PDT)

PDT is a 120-minute session
Presented by Dr. Marjaneh Hejazi
Duration of session is 120 minutes
Date of presentation: 12/13/2021

Learning Objectives

Understanding the necessity of radiation dosimetry for treatment planning in biomedical applications
Learning about laser applications
Introduction of medical physicists in therapeutic hospital departments

Keywords

Photodynamic therapy
Physics
Dosimetry

References

Zhu, T.C., & Finlay, J.C. (2008). The role of photodynamic therapy (PDT) physics. Medical physics, 35(7Part1), 3127-3136.
Kim, M.M., & Darafsheh, A. (2020). Light sources and dosimetry techniques for photodynamic therapy. Photochemistry and photobiology, 96(2), 280-294.
Makropoulou, M., Kareliotis, G., Spyratou, E., Drakaki, E., Serafetinides, A.A., & Efstathopoulos, E. (2019). Non-ionizing, laser radiation in Theranostics: The need for dosimetry and the role of Medical Physics. Physica Medica, 63, 7-18.

Today's Content

Introductory remarks on laser radiation
Laser-tissue interactions and photobiological mechanisms
Biomedical laser applications in phototherapy
Current areas of basic PDT research
PDT dosimetry
PDT future research
Summary

1. Introductory Remarks

Laser discovery in 1960
Emphasis in 21st century
Enthusiasm in the field

2. Laser Radiation

Definition, properties, and biomedical applications
Lasers for cosmetic applications (wrinkle removal, hair removal)
Different wavelengths and their applications (e.g., 1320nm, Er, CO2, KTP, Ruby, Nd:YAG, 1450nm)
Properties of lasers and their application
Advantages of lasers

3. Laser-Tissue Interactions and Photobiological Mechanisms

Photochemical effects resulting from molecular photo-excitation via photon absorption
Chemical reactions such as production of free radicals and reactive oxygen species (ROS)
Interactions between power density and exposure time

4. Biomedical Laser Applications

Photodynamic therapy (PDT) of tumors
Biostimulation for wound healing (low-level laser therapy)
Photochemical ablation and photodisruption

4. Definition of PDT

Light-activated chemotherapy using photosensitive drug accumulation
Causing oxidative injury to cells

4. PDT Technique

Non-invasive technique employing three factors:
- Photosensitizing agent (PS) for targeting malignant cells
- Molecular oxygen (O2) producing reactive singlet oxygen
- Non-thermal monochromatic light irradiation

4. Type II Mechanism

Photon absorption by the sensitizer
Energy transfer to oxygen creating reactive singlet oxygen

4. Singlet Oxygen

An unstable form of molecular oxygen
A key factor in PDT's mechanism of action

5. Current Areas of Basic PDT Research

Photon use in the 600-850nm region of the electromagnetic spectrum
Diode lasers are fixed wavelength, and a unique laser unit is required for each photosensitizer
Clinical diode lasers provide up to 1 W/cm^2 irradiance
Diode lasers with outputs between 415-690 nm wavelength are commonly used in PDT

5. Dosimetry

Implicit Dosimetry: Using a metric (like photobleaching) that incorporates dose factors indirectly.
Explicit Dosimetry: Measuring each dose parameter separately and combining them using a model.
Direct Dosimetry: Method of directly measuring parameters in PDT

6. PDT Future Research

Efficacy in various malignant/premalignant conditions (head/neck, lung cancer, mesothelioma, Barrett's esophagus, prostate cancer, and brain tumors)
Targeted delivery of photosensitizers with nanotechnology
Synthesis of high tumor uptake selectivity nanoparticles

6. PDT Future Steps

Combining external beam radiation therapy
Using radioluminescence of nanoparticles
Down-converting xray radiation into visible light for adjacent photosensitizer activation

6. PDT Future (cont.)

High energy delivered (4-5 orders higher than in radiation therapy)
Miniaturized wireless implantable device with LEDs for local light delivery and dosimetry

Conclusion

Need for well-trained medical physicists in both radiation and laser-matter interactions, for dosimetry, treatment planning and safety
Bridging ionizing radiation and non-ionizing laser radiation in oncology treatment

Summary

PDT is a light-activated chemotherapy used in treating various diseases.
It depends on the combination of photosensitizing agent, molecular oxygen, and light irradiation.
Safety for patients and medical personnel relies on qualified expertise.
Ongoing research focuses on better understanding of photobiological mechanisms and optimization of clinical applications.

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Description

Test your knowledge on laser safety protocols and the role of Medical Laser Safety Officers in healthcare. This quiz covers key articles on light sources, dosimetry techniques, and safety responsibilities in laser applications. Perfect for professionals in the biomedical field seeking to understand safe laser practices.