Lecture 1 Overview Flashcards
What is the role of CT in RT?
- Diagnosis and staging
- treatment planning
- online / office verification
- adaptive radiotherapy
- follow up assessment
What is the role of CT in treatment planning?
- no geometric distortion
- provide hounsfield unit that can be converted to electron density date
- important for dose calculation
What are the pros of CT in treatment planning
- no geometric image distortion
- fast image acquisition time
What are the cons of CT in RT treatment planning?
- poor soft tissue contrast
- lack of functional information
- image artifacts
What are the Pros of MRI for radiotherapy ?
- variety of image contrast
- no radiation
- superiority in soft tissue contrast over CT
- flexible in image plane selection
- function and molecular imaging
- real time imaging
==> boundaries of the tumor can be clearly defined
What are the role of PET image in radiotherapy planning?
- Provide information of biochemical function of tissues and organs
- Provide information in microscopic spread of disease
What is the definition of image registration?
Transformation of different set of image data, can by multi-modality, into one coordinate system.
Name 3 major registration methods
- Manual rigid registration
- Automatic rigid registration
- Automatic deformable registration
What is the definition of IMRT?
Intensity modulated radiotherapy
= the act of varying the radiation intensity across the beam
IMRT VS 3DCRT ?
V higher target conformity
V increase sparing of critical structures
X increased low dose region due to large number of field used
What variables can be manipulated during beam on in VMAT?
- MLC positions
- gantry speed
- dose rate
- collimator angle (Elekta only)
What is the advantage of VMAT over IMRT?
Higher speed of delivery
Definition of SRS
Stereotactic radio surgery
= the use of a stereotactic apparatus and energetic radiation beams to irradiate the intracranial lesion with a single treatment
Definition of SRT.
the use of stereotactic apparatus and radiation beams for multiple fractions or treatments
Definition of SBRT?
Stereotactic body radiation therapy
= the lesion is outside of the brain. The combine use of stereotactic apparatus and radiation to irradiate the lesion with a single treatment or a few fractions
What are the benefits of knowledge-based planning?
- plan quality can rival human expert planner
- planning time can be fast
- allow more freedom
- allow interactive process
- integrate will all sources of knowledge
- truly individualised, patient-specific treatment planning
What s the role of 4DCT?
Reduce margin and create individualised ITV
HyperArc features?
- non coplanar
- multiple lesions
Halcyon features
- ring based system, 4 full rotations per min
- 6MV flattening filter free
- maximum field size 28 x 28
- max dose rate = 800 MU/min
- dual -layer MLC, max velocity = 5cm per sec
What is dynamic electron arc radiotherapy?
- Electron is delivered in arc mode
- couch and gantry move together,
- beam always normal and SSD = 100
- couch motion, gantry rotation and dose rate can be modulated to produce desirable dose distribution
What are the planning process of MR only treatment planning
- Acquire MRI image (multiple sequence.)
- Correct geometric distortion (systemic and patient specific distortion)
- Correct local motion and movement (if neccessary)
- Classify tissue / materials (generate external / air / vessel masks, classifify tissues using FCM-spatial constraints)
- Synthsize MRCT volumes (assign electron density with weights)
- Treatment planning (contouring / dose calculation / image guidance)
What are the two methods in autosegmentation?
- Deep learning
- model learn directly from large number of training example
- apply knowledge to new scans - Atlas-based methods
- deformable image registration of datasets onto new scans
