Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Patient Care > Leksell Gamma Knife > Flashcards

Leksell Gamma Knife Flashcards

1
Q

What is stereotactic irradiation (surgery)?

A

Refers to the delivery of radiation using stereotactic (accurate positioning of probes inside the brain or other parts of the body, based on three-dimensional diagrams) principles.

Delivery of a high dose radiation to small region usually within a well-immobilized system that conforms closely to the 3D shape of the target volume while ensuring rapid fall-off to the surrounding normal tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is ablative doses?

A

Ablation radiation: highly focused radiation treatment that gives an intense dose of radiation concentrated on a tumor, while limiting the dose to the surrounding organs

Utilizes 3D coordinate system with the highest possible accuracy/precision using a single of few fractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Conventional radiation therapy: Breast Cancer

A

Breast cancer

30-35 fractions, 1.8 Gy/fraction → 60-66 Gy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Conventional radiation therapy: Prostate cancer

A

Prostate cancer

35-45 fractions, 1.8 Gy/fraction → 75 Gy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Conventional radiation therapy: Lung cancer

A

Lung cancer

25-35 fractions, 1.8-2.0 Gy/fraction → 50-60 Gy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does stereotactic regimen typically consist of?

A

1-5 treatment sessions, each with a high dose per fraction, usually between 8-24 Gy (hypofractionated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Stereotactic Radiosurgery (SRS)?

A

Single, LARGE fraction

Intracranial

(GK delivers this*)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Stereotactic Body Radiotherapy (SBRT)?

A

1-5 large fractions

Extracranial (big, blue, body bags in room E)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Who invented Stereotactic Radiosurgery?

A

Professor Lars Leksell in 1950’s in Stockholm, Sweden

With Elekta, developed the Leksell Gamma Knife

Current model used it Gamma Knife Icon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fun fact (not so fun fact)

A

Suddam Hussein had his own Leksell Gamma Knife in his bunker.

Brain cancer? Or was the 40 Cobalt sources in GK used to make weapons?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

GK Indicators: Benign Brain Tumors

A

Benign: not cancer, no threat to host UNLESS in the cranium as it can push on vital brain regions

  • Meningioma (lining of brain)
  • Acoustic Neuroma/Schwannoma
  • Pituitary Tumor
  • Chordoma
  • Craniopharyngioma

Vascular Disorders: AVM (arteriovenous malformation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

GK Indications: Malignant Brain Tumors

A
  • GBM
  • Astrocytoma
  • Oligodendroglioma

Metastatic Disease: Lung and Breast most common

Functional Disorders: Trigeminal Neuralgia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is GK an option?

A

Kind of tumor

Rule of thumb: no larger than 35 mm in diameter

Pressing on critical structure and producing symptoms (does NOT help mass effects)

Age and health of patient

How good are alternatives

Patient’s preferance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Top 3 NMH Indications Treated

A
  1. Brain mets
  2. Glomus
  3. Glial Tumors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Top 3 NMH Metastatic Population

A
  1. Lung
  2. Breast
  3. Others
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The Physics and Basic Principles of GK

A

GK uses Cobalt-60 as radiation source which undergoes beta decay; as part of decay process, gamma rays are emitted

  • Recall, x-rays and gamma rays are exactly the same except their origin

Inside GK unit there are 192-201 Co-60 sources

Dose distribution is modified by using combination of isocenters and positions, using different collimators, and different dwell times, and highly sophisticated treatment planning

GK operates on principles of stereotaxy to achieve high level of precision

17
Q

GK Radiosurgery

A

Delivery of single, high dose radiation to a small and critically located intracranial volume though the intact skull

192 narrow, pencil like beams intersecting in one focal point

18
Q

Cobalt Delivery Systems

A

4 C Collimator System (where head/helmet goes)

Sector system (the inside portion)

19
Q

Treatment Procedure [for frame]

A
  1. Frame Fixation (frame vs. frameless)
  2. Diagnostic imaging
  3. Treatment planning
  4. Treatment
20
Q
  1. Frame Fixation
A

Patient fixation

Establish spatial reference for the planning phase

Fiducial box and measurements

21
Q
  1. Diagnostic Imaging
A

MRI, CT Scan, Angiogram with frame on

Coordinate frame provides optimal stereotactic localization

Digital image transfer to Leksell Gamma Plan

22
Q
  1. Treatment Planning
A

Leksell Gamma Plan provides:

  • Surgical precision (hence gamma KNIFE)
  • User-friendly software dedicated for GK Surgery
  • Fast creation for optimal treatment plan
23
Q
  1. Treatment Planning - Leksell Gamma Plan
A
  • Tailor made surgical planning
  • Real time dose calculation
  • Integrated dose plan optimization
  • Full 2D/3D image and dose display
24
Q
  1. Treatment Planning - Gamma Knife Dosing
A

Based upon indication treated, size, location and critical structures

  • Bigger volumes = smaller dose
  • Pinpoint doses to critical structures

Acoustic Neuroma → 1200 cGy/ 50%

AVM → 1600 cGy - 2000 cGy/ 50%

Meningioma → 1600 cGy/ 50%

Metastatic Disease → 1600 - 2400 cGy/ 50%

Trigeminal Neuralgia → 8160 cGy/ 100 %

25
Q
  1. Treatment
A

Delivery of Cobalt Radiation

Automatic Treatment (Redundant safety and verification systems)

Patient communication (Audio-Visual system)

26
Q

Follow-up

A

Biological effect of GK:

  • Damages to DNA of the tumor cells
  • AVMs – cause blood vessels to thicken and close off
  • Minimal damage to surrounding tissue

Effects of treatment will occur over a period of time

Follow up imaging

  • Depends on what was treated
  • Typically MRI in 3 months
27
Q

Patient Care Considerations Post Frame-Based GK

A
  • Band-aids
  • Slight bleeding at pin sites
  • Headache
  • Swelling above the eyes
  • Ice packs
  • Elevate head
  • Possible Steroid (Decadron)
  • Radiation Necrosis
28
Q

Treatment Procedure [frameless]

A
  1. Diagnostic imaging
  2. Simulation (mask-making)
  3. Treatment planning
  4. Treatment(s)
29
Q
  1. Diagnostic Imaging
A

MRI – typically morning of simulation or within the week prior to simulation

30
Q
  1. Simulation
A

Headrest/Mask (20 min in oven, 20 minutes to shape/cool)

Patient comfort

  • Table height
  • Music
  • Ativan if claustrophobic

Reference CBCT

Test HDMM

31
Q
  1. Treatment Planning
A

Physics will fuse reference CBCT with MRI

Same planning process as frame-based (Gamma Plan)

32
Q
  1. Treatment(s)
A

Daily CBCT prior to treatment

  • Match current CBCT with reference CBCT
  • Review of dosimetry prior to starting treatment
  • Adjust table positioning/shots based on positioning

1-5 fractions

Monitor motion entire treatment (1 mm or 1.5 mm tolerance)

3-month follow-up with MRI

33
Q

Frame vs. Frameless

A

Influencing factors:

  • Location of lesion(s)
  • Number of lesions
  • Treatment time
  • Patient preference/status
34
Q

Advantages of GK?

A
  1. Accuracy
  2. Faster recovery to normal life vs. Surgery & WBRT
  3. One time treatment
  4. Reduced costs per patient
  5. No intensive and minimal post-operative care
  6. Few support staff required
35
Q

Disadvantages of GK?

A
  1. Size limitation
  2. Invasive frame application
  3. Does not treat whole brain
  4. Not an immediate response
  5. Cobalt Sources
    1. Half life of 5.26 years and thus needs to be replaced

Patient Care (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions