Biomedical Instruments Flashcards
1
Q
What are 3 examples of Radiation Therapy
A
- X-Ray
- Gamma Knife
- Hadron Therapies
2
Q
What is the Goal of Radiation Therapy
A
- Use radiation to KILL cancer tumor tissues while minimizing damage to healthy tissue
3
Q
What does dose mean in Radiation Therapy? What does it generate?
A
- Measure of energy deposited by the radiation in the body
- This energy generates ionization of cell molecules that ultimately leads to cell death
4
Q
X-rays deposit more dosage at which penetration depth? What about ions such as protons and carbon?
A
- More energy near the body entrance for X-rays
- Protons and Carbon concentrate more dose at the tumor (more penetration)
5
Q
The depth of the energy deposition peak (Bragg peak) can be efficiently tuned by changing what?
A
Changing the ION ENERGY!
6
Q
Killing Cancer cells by these radiation therapies induce what?
A
Induce SIGNIFICANT DNA DAMAGE to prevent cell replication
7
Q
Double strand break of the DNA is required since cells are very efficient at repairing single strand breaks by two mechanisms. Name them!
A
- Direct Route
- Ionization of DNA directly from the radiation - Indirect Route
- Radiation interacts with water (H2O) to create free radicals HO- which then induce DNA damage
8
Q
Explain Stereotactic Radiosurgery
A
- Called “Stereotaxy”
- Non-invasive form of “surgery”
- Results compare to conventional surgery
- Highly precise delivery of radiation (accurate to 1-2 mm of target)
9
Q
What does Stereotactic Radiosurgery rely on?
A
- 3D imaging (such as CT scan)
- Highly focused gamma ray beams
- Image-guided radiation therapy
10
Q
Names Treatment applications of Stereotactic Radiosurgery
A
- Brain tumors
- Arteriovenous malformations (AVMs) = Tangling of expanded blood vessels limiting blood flow
- Trigeminal neuralgia
- Tremors
- Epilepsy
11
Q
Case SCENARIO!!!!
A patient has headaches and nausea, diagnosis involves an MRI where we diagnosed a Benign Brain Tumor
What is the treatment of choice?
- Chemo/Immuno therapy?
- Invasive Brain Surgery?
- Non-invasive radiotherapy?
- Non-invasive stereotactic radiosurgery?
A
- Chemo/Immuno therapy? No, Blood brain barrier
- Invasive Brain Surgery? No, High risk
- Non-invasive radiotherapy? No, too non-specific
- Non-invasive stereotactic radiosurgery? YES! Localization of specific area for radiation
12
Q
Break time?
A
Nah lol
13
Q
Explain 3D Stereotactic Localization
A
Goal: Target tissue of interest with as much accuracy as possible
Use imaging and 3D mapping techniques to target tissue of interest (EX. X-ray, PET, MRI, etc)
14
Q
Describe Tomographic Techniques
A
- PET (CT) and MRI
- Good for tumor pathologies
- Use multiple layers to get 3D image
15
Q
Describe X-Ray based Techniques
A
- X-ray and Digital Subtracted Angiography
- Good for vascular imaging (for treatment of vascular malformations)
- Use pins and depth perception methods to get 3D localization
16
Q
Describe Radiosurgery
A
- Focused radiation beams delivered to a
specific tissue volume - Multiple beams or multiple passes
(fractionated treatment) that intersect - Keeps radiation exposure to surrounding tissue at
benign levels - Treats targeted tissue (the point of intersection)
with a higher dose of radiation
17
Q
How is Radiosurgery therapeutic?
A
- Radiation does NOT remove the tumor or tissue abnormality
- For tumors, radiation distorts DNA (ionizing radiation induces mutations and other forms of DNA damage)
18
Q
How long does it take for a benign tumor to disappear?
What about Metastatic (Cancerous) tumors (with a much faster growth rate)?
A
- Benign = Up to 2 years
- Metastatic = Only months
19
Q
What are some side effects of Radiosurgery?
A
- Swelling: Cells lose ability to retain fluid, edema may occur
- Necrosis: Dead tumor cells may cause complications (inflammation, fibrosis)
- Psychological side effects: Loss of memory and decreased cognitive abilities
- Radiation-induces tumor/cancer: Radiation-induced mutations may result in a new tumor or cancer
20
Q
What are the applications of Radiosurgery?
A
- Mostly used for CNS, head and neck surgery
21
Q
What are the different types of radiation plus their sources
A
- High energy X-Ray: from Linear accelerator systems
- Gamma Radiation: From Cobalt-60 source
- Proton: From particle beam or cyclotron
22
Q
Explain Gamma Knife
A
- From Cobalt-60 source
- Uses multiple beams to treat tissue volume
- Multiple targets can be easily treated in one session
23
Q
Explain LINAC (Linear Accelerator-based) systems
A
-Less accurate
- In use in more hospitals
- Less efficient (longer treatment times)
24
Q
Explain CyberKnife
A
- Can treat most regions of body
- w/ Stereotactic frame, can approach accuracy of LINAC or GammaKnife
25
What is the process of Gamma Knife
- Injected with contrasting fluid and medicine
- Patient first gets a CT or MRI scan of the target area
- A computer takes the images created and combines them to form a 3-D map of the target area
- The head frame is then placed on the patient as the
operator sees fit
- The patient then lies on a special bed that moves backward into the machine
– While the bed moves into the machine, beams shoot from all different directions towards the target area with the guidance of the 3-D map
26
What are the ADVANTAGES of Gamma Knife
- Able to reach tumors that are unreachable by conventional surgery
- Stops the growth by altering DNA
- No physical cuts involved (non- invasive)
- Extremely accurate
- Takes less time to complete (30-60 minutes) than comparable therapy treatments
- More effective than comparable therapy treatments
- Cost covered entirely by some medical insurance companies
- Less side effects than other treatments
27
What are the DISADVANTAGES of Gamma Knife
- Side effects exist like fatigue, headaches, brain swelling, etc.
- Cannot destroy the tumor
- Expensive (if not covered by insurance)
- Results take time
28
Explain LINAC-based systems in terms of accuracy and efficiency
- Less accurate
- In use in more hospitals
- Less efficient (longer treatment times)
29
Explain CyberKnife
- Can treat most regions of body
- w/ Stereotactic frame, can approach accuracy of LINAC or GammaKnife
30
Recognize the Radiosurgery history
- Professor Lars Leksell, a Swedish neurosurgeon, first developed stereotactic devices (used to guide the gamma rays) as well as the very concept of radiosurgery in the early 1950’s.
- Together with Borje Larsson, a physicist, Leksell built the first Gamma Knife unit in Sweden in 1968.
- Since that time, this non-invasive technique for the treatment of brain tumors and vascular malformations has enjoyed incredible success.
- More than 60,000 patients have been safely treated with focused gamma rays world-wide.
31
Compare Gamma Knife to Radiation Therapy
- With standard external beam radiation therapy techniques, tumors and much or all of the
surrounding brain are treated to the same dose of radiation.
- There is increasing evidence that over long periods of time, high doses of radiation are harmful to
normally functioning brain. The technique of Gamma Knife radiosurgery treats only the abnormal tissue, in a single session, without significant radiation to adjacent brain.
32
What are the 4 Forces of Nature
1. Strong Nuclear Force
2. Weak Nuclear Force
3. Electromagnetic Force
4. Gravitational Force
33
What are Hadrons?
- Subatomic particles which experience the STRONG NUCLEAR FORCE
- They are composed of fundamental particles called quarks, anti-quarks, and gluons
- Hadrons are divided into 2 categories based on type of quarks they are: Baryons and Mesons
34
Define Baryons
- One of the categories of quarks
- STABLE!
- Proton and Neutron
35
Define Mesons
- One of the categories of quarks
- NOT STABLE!
- Kaon, Antiproton, Antineutron
36
Higgs boson particle is known as the
" God particle"
37
Why are Hadrons useful in Cancer Therapy?
- Penetration depth can be well defined and adjustable
- Most energy deposited at end-of-range
- No dose beyond target
- Leak to normal tissue minimized
- Good tumor kill
38
Hadrons can reach a depth of what?
In slideshow, it went as deep as 25 cm which is a lot more than X-rays for instance.
39
Compare Fission to Fusion
- Fission: Break one molecule into two. Easy to get started. Not as safe.
- Fusion: Combine 2 into one. Tremendous amount of energy required to initiate reaction. Safer to use.
40
Explain the properties of Neutrons
- Mass = 1.67 e^-27 kg
- No Charge
- Indirectly Ionizing Radiation
- Neutron Half-life = 10 minutes
41
All neutrons are initially what?
All neutrons are initially FAST Neurons which lose kinetic energy through interactions with their environment until they become thermal neutrons which are captured by nuclei in matter
42
Explain the properties of Protons
- Mass: 1.67 e^-27 kg
- Positive Charge
- Directly Ionizing Radiation
- Proton Half-life = 10^35 years
43
Understand Proton vs Photon Depth Dose in Water
- Look at slides
- Increasing energy 130MeV --> 190 MeV increase depth of penetration.
- Higher energy = more depth
44
Defend why Protons are of good use
- Protons have GOOD DOSE distribution
- Low entry dose
- Most of the energy deposited at a SPECIFIC DEPTH
- No dose beyond specific range (minimizing damage to surroundings)
45
Make sure you can compare Protons and X-Ray
- Protons: More directly radiated to a specific range
- x-Ray: Target not just the specific range, but surrounding cells as well. X-Ray is not as good in targeting as protons.
46
Custom components involved in proton therapies
Range compensator:
- Made of GLASS-like which conforms dose distribution to the DISTAL shape of the target
- Made from water equivalent material
Beam Aperture:
- Made of BRASS and it Conforms dose distribution LATERALLY
47
What are Heavy Ions?
-Ionized atoms which are usually heavier than Carbon
- Refers to atoms that are generally completely ionized i.e. they are bare atomic nuclei
- Ex.) C, Si, W, Au, Pb, U
- The nuclei can be directed to a fixed target, or can be split into two beams moving in opposite directions that are brought into collision at a well-defined spot
48
Collision of heavy ions can produce what?
HADRONS!!!
49
Explain Fusion Reaction
- More energy produced than Fission Reaction
- No harmful radiation produced
50
E = mc^2 Special Theory of Relativity
What is the correct/full equation?
Correct equation is:
E= mc^2/ sqrt(1-V^2/C^2)
51
What are the 3 Laws of Robots by Isaac Asimov
1. A robot may NOT injure a human being or, through inaction, allow a human being to come to harm
2. A robot MUST obey the orders given it by human beings, except where such orders would conflict with the First Law
3. A robot MUST protect its own existence as long as such protection does NOT conflict with the First or second Law
52
Briefly describe the PUMA 560 CT guided brain biopsy device
- A robot with improved absolute positioning accuracy for CT-guided stereotactic brain surgery
- Collect biopsies of brain and neck region
53
Explain the Da Vinci Surgical System
- 1st robotic system approved by the FDA for general laparoscopic surgery
- The 1cm diameter surgical arms represent a significant advancement
- Extend the benefits of minimally invasive surgery to patients
- 3D magnification screen allows the surgeon to view the operative area with the clarity of high resolution
54
Pros and Cons of Robotic technology for surgery for Patients
Pros:
- Fast recovery
- Less pain
- Less scarring
- Less loss of blood
- Less need for blood transfusion
- Smaller incision
Cons:
- Inexperienced surgeon
- Power/Network dependent
- Expensive
55
Pros and Cons of Robotic technology for surgery for Surgeons
Pros:
- Less liability for the surgeon
- Surgeons are less fatigued
- More comfortable during surgery
- Better visibility during surgery
- Da Vinci is dependent on surgeons
Cons:
- Cost about $2.5 million
- Steep learning curve
- Not easy to operate
