ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof...
Transcript of ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof...
![Page 1: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/1.jpg)
ATTENTION! The whole content of the lecture with all the
animations can be dowloaded from:
http://www.onko.szote.u-
szeged.hu/letoltes/radioter_phys_basis/radiother_phys_basis.zip
Size > 300 M!!!
The dowloaded .zip fijle should be unpacked into an independent
new folder, than please start the file named
„Part 1.ppt”. The embedded icons will show/play the pictures or
films. At the end of the presentation please continue with Part 2.ppt
and than with Part 3.ppt!
![Page 2: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/2.jpg)
Radiation TherapyTechnical Aspects
![Page 3: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/3.jpg)
Introduction
Treatment modalities for cancer:
Surgery – Radiotherapy – Chemotherapy
Radiotherapy – 50% of patients
About 60% of all tumor patients can be
considered to be potentially curable.
(Malignant localized tumor, no metastatic
disease)
The aim: to deliver a radiation dose, to kill all
tumor cells.
Difficulties: OAR are located close to the tumor
![Page 4: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/4.jpg)
The double goal of radiation therapy:
• Increase the dose to the target volume !
• Decrease the dose to healthy tissue !
1. better tumor control
TCP – Tumor Control Probability
2. decrease of side effects
NTCP – Normal Tissue Complication
Probability
These means higher probability of patient cure.
![Page 5: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/5.jpg)
CONVENTIONALCONFORMAL
![Page 6: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/6.jpg)
CONVENTIONALCONFORMALIMRT
![Page 7: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/7.jpg)
The course of radiotherapy
Radiotherapy treatment chainRadiotherapy treatment chainRadiotherapy treatment chainRadiotherapy treatment chainRadiotherapy treatment chain
![Page 8: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/8.jpg)
I. Patient Immobilization
High TU dose, low dose at OARs
Sophisticated delivery techniques very steep
dose gradient between target and the organs at risk
patient immobilization is a crucial issue.
Setup errors – underdosage in the target,
overdosage in the normal tissue.
General Considerations
1. Definition of Target Volumes (ICRU 50, ICRU 62)
GTV (Gross Tumor Volume) – the clinically evident
target volume, visible in diag. images.
CTV (Clinical Target Volume) – GTV + margin
(containing micr. population of tumor cells)
PTV (Planning Target Volume) – accounts for setup
uncertainties, organ motion and deformation
![Page 9: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/9.jpg)
The PTV should have a high probality of containing the CTV during the whole treatment
IMMOBILIZATION
2. Sources of Uncertainties
a. Patient setup uncertainties
b. Organ motion and deformation
3. Design Requirements
General intention to reduce the CTV – PTV safety margins.
High reproducibility.
Compatible with the imaging modalities.
Practical and easy to use.
Comfortable for the patient.
![Page 10: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/10.jpg)
Immobilization Techniques
Head targets: Invasive fixation – radiosurgery
total dose – in a single fraction
Overall setup uncertainty < 1mm
![Page 11: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/11.jpg)
INVASIVE FIXATION
![Page 12: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/12.jpg)
Non-invasive fixation
bite blocks and/or face masks
mask – individually fabricated for each patient
thermoplastic material, polyurethane foam, self-hardening Scotch-cast bandages.
![Page 13: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/13.jpg)
MASK OF SCOTCH –CAST BANDAGES
![Page 14: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/14.jpg)
Extracranial Targets
much more challenging
rotations around the body axis
target position may change within the body
organ motions
Several possible solutions
Vacuum pillows
Evacuated flexible bags
Self-hardening bandages – thermoplastic sheets, bandages.
Decreasing of movements caused by breathing
Breast Treatments
one of the most complicated problems
fixation of opposite side mamma
position of arms
![Page 15: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/15.jpg)
VACUUM PILLOW
![Page 16: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/16.jpg)
VACUUM PILLOW PRODUCTION
![Page 17: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/17.jpg)
VACUUM FIXATION SYSTEM
![Page 18: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/18.jpg)
SELF-
HARDENING
BANDAGES
![Page 19: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/19.jpg)
ABDOMINAL
COMPRESSION
DEVICE
![Page 20: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/20.jpg)
II. Imaging
Imaging for therapy planning serves the following purposes• A target volume (TU) and the organs at risk are the basis for therapy
planning. 3D patient model beam directions are optimized.
• The dose is calculated based on CT data. DVHs can be plotted for the tumor and the organs at risk.
• A 3D-anatomical model is also required for positioning of the patient at the therapy device.
A 3D-model is normally obtained using X-ray computed tomography (CT).
Functional imaging (MRI, PET, SPECT)
useful for the definition of tumor, allows the visualization of microscopic
disease outside the region of highest cell density.
1. X-ray Computed Tomography (CT)
2. Magnetic Resonance Imaging (MRI)
3. Nuclear Medicine SPECT (Single Photon Emission Tomograph)
PET (Positron Emission Tomograph)
![Page 21: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/21.jpg)
III. Tumor Localization
Before image data can be used for radiation treatment planning relevant structures have to be identified
– Which structures are important?
– How structures and volumes can be delineated?
– How can be combined different modalities?
1. Volume Definition
Two different kinds of structures are important
– The target volume
– The organs at risk (OAR),which have to be spared.
ICRU Report 50 (1993) és ICRU Report 62 (1999)
(International Commission on Radiation Units and Measurements)
GTV, CTV, PTV
– GTV – Gross Tumor Volume
– CTV – Clinical Target Vomume (GTV+margin)
– PTV – Planning Target Vomume (CTV+margin)
![Page 22: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/22.jpg)
IMPORTANT STRUCTURES
![Page 23: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/23.jpg)
VOLUMES in ICRU 50
![Page 24: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/24.jpg)
2. Image segmentation
Segmentation – the process of distinguishing relevant structures/volumes from the background.
1 slice – 2D segmentation
More than 1 slice – 3D segmetation
Segmentation in radiation treatment planning
_- delineating the PTV
– delineating the organs at risk
– delineating the surface contour of the body
Manual segmentation
Semiautomatic segmentation algorithms
Automatic segmentation algorithms
Two groups of segmentation algorithmsRegion-based approaches (find an area of similar properties)
Edge detection algorithms (look for sudden changes)
![Page 25: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/25.jpg)
3. Image Registration
Image sequences of various modalities are used:
CT, MRI, PET, SPECT
A definite relation is necessary between the picture elements (pixels).
Registration : methods which are able to calculate these relations (transformations)
Eg. At least 3 corresp. pairs of points transformation
matrix calculation correlation between the two sequencies.
Manual registration: user interaction
Semiautomatic registration: partly user interaction
Automatic registration: do not require any user interaction
Scope of transformation: global and local
Geometrical properties: rigid –elastic transformation
Image fusion – Display of registered image sequences
![Page 26: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/26.jpg)
PARALLEL DISPLAY
![Page 27: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/27.jpg)
SLIDING WINDOW
![Page 28: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/28.jpg)
INTERACTIVE MATCHING
![Page 29: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/29.jpg)
IV. 3D Treatment Plannig
The goal of planning: to find the optimal treatment plan.
Based on 3D model of patient anatomy.
- to find the optimal beam directions.
- to form the beam shape exactly to the tumor
shape (to minimize the dose to healthy tissues).
- to accurately calculate the physical dose distribution.
The 3D patient model is based on
- 3D tomographs (CT,MR,PET)
- 2D slices 3D (image cube)
3D Model
![Page 30: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/30.jpg)
3D patient model
![Page 31: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/31.jpg)
3D navigation
![Page 32: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/32.jpg)
- Contouring transformation to a 3D model
(interpolation)
The Radiotherapy Planning Cycle
- a series of beams are applied in order to concentrate the
dose on the target volume.
- the beams (dose) are superimposed on the target.
- the healthy tissues can be kept below tolerance lewels.
![Page 33: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/33.jpg)
The 3D model
![Page 34: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/34.jpg)
Dose distributions
![Page 35: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/35.jpg)
THE PLANNING CYCLE
Acquisition of CT(MR,PET)image sequences
Definition of tumor, target volume and organs at risk
Definition of treatment parameters
Virtual therapy simulation
Dose calculation
Evaluation of dose distribution
Patient treatment
Optimization
![Page 36: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/36.jpg)
1. Definition of Beam Directions
- Spatial relations between target volume and organs at risk!
- Main criterion: the target volume is enclosed completely by the beam without enclosing any organs at risk. If it is not possible, to minimize the volume of organ at risk covered by beam.
Tools: Beam's Eye View (BEV)
The planner views the 3D-model from the position of the radiation source.
Interactive Beam’s Eye ViewBeam’s Eye View
![Page 37: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/37.jpg)
Beam's Eye View
![Page 38: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/38.jpg)
Beam's Eye View
BEAM 1 BEAM 2 BEAM 3
![Page 39: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/39.jpg)
Beam's Eye View
BEAM 1 BEAM 2 BEAM 3
![Page 40: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/40.jpg)
Beam's Eye View
BEAM 1 BEAM 2 BEAM 3
![Page 41: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/41.jpg)
Beam's Eye View
![Page 42: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/42.jpg)
- Observer's View
presents the 3D model from an arbitrary
point of view.
Helps to minimize that subvolume where the single
beams overlap.
- Spherical View
Observer’s ViewObserver’s View
Spherical View
![Page 43: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/43.jpg)
Observer’s View
![Page 44: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/44.jpg)
Observer’s View
![Page 45: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/45.jpg)
Spherical View
![Page 46: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/46.jpg)
2. Additional Treatment Parameters
Irradiation directions and beam shapes
A series of other parameters:
- Selection of radiation type: fotons - generally
electrons – superficial tumors
protons, heavy ions
- energy of radiation, beam quality
- beam modifying devices
bloks, wedges, compensators, dynamic
collimátors etc.
It is possible to shape the 3D dose distribution
to better match to the form of target volume.
![Page 47: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/47.jpg)
3. Dose Calculation
- A dose calculation algorythm calculates the
expected dose distribution using the beams
specified.
4. Evaluation of Treatment Plans
Several alternative configurations can be compared
and the most suitable one used.
Qualitative Evaluation of Dose Distribution
Biological Models : TCP, NTCP
Forward Planning, Inverse Planning
![Page 48: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/48.jpg)
Forward and Inverse Planning
![Page 49: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/49.jpg)
- 3D dose distribution: isodose surfaces
- Isodose distribution from slice to slice:
isodose lines, color wash
- Dose-Volume-Histograms
DVH – a simple way of displaying the 3D dose
distribution.
DVHs usually are displayed as cumulative histograms
showing the fraction of the total volume receiving doses
up to a given value.
![Page 50: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/50.jpg)
3D isodose distributions
![Page 51: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/51.jpg)
2D isodose distributions
![Page 52: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/52.jpg)
Dose-Volume- Histograms
![Page 53: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/53.jpg)
V. Patient Positioning
Substancial role in radiation therapy:
Fixation and immobilization of patient
Absolute positioning at the irradiation device.
1. Step: Definition of patient-fixed coordinates.
2. Step: Image acquisition.During planning target point is calculated in patient-fixed coordinates.
3. Step: Patient positioning at the irradiation device, immediately before treatment.(To move the target point to the isocenter)
![Page 54: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/54.jpg)
Patient-fixed coordinate system
![Page 55: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/55.jpg)
Patient-fixed coordinate system
![Page 56: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/56.jpg)
Image acquisition and target point coordinates
![Page 57: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/57.jpg)
Positioning at the irradiation device
![Page 58: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/58.jpg)
Positioning at the irradiation device
![Page 59: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/59.jpg)
2. Portal Films and Electronic Portal Imaging
Films: provide information for repositioning of patients, from fractions to fractions.
Electronic portal imaging devices (EPID): real time images, time efficient patient positioning.
Types:Fluoroscopic systems, scintillation screen – camera.
Ionization chamber arrays, e.g.256 x 256.
Patient positioning based on external markers and anatomical points . (Final control.) Comparison of :
Simulator images Port images
DRR Port images
![Page 60: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/60.jpg)
The Beamview system
![Page 61: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/61.jpg)
X-ray images and electronic ports
![Page 62: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/62.jpg)
VII. The Treatment
A. Treatment modalities
1. Linear Accelerators (Linacs)
Basic idea : to accelerate electrons in the field of electromagnetic wave travelling in a waveguide.
Principle of an elementary linac: X-ray tube
A high voltage of several MVs means a big insulation problem or a great tube size.
Instead of high-voltage a series of smaller voltage are applied.(These fields are produced by microwaves)
![Page 63: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/63.jpg)
Linac
![Page 64: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/64.jpg)
Increase of electron speed with energy
![Page 65: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/65.jpg)
Concept of an elementary accelerator
![Page 66: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/66.jpg)
Microwave cavities
electron oscillations in the wall,
acceleration of electrons in the cavities.
Travelling-wave Accelerator:
a series of microwave cavities of a length equal to one-quarter wavelength.
for a 10 MeV electron beam 125 cm length
at higher energies standing wave waveguide
![Page 67: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/67.jpg)
Principle of electron acceleration
![Page 68: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/68.jpg)
Travelling wave acceleration
![Page 69: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/69.jpg)
Travelling wave acceleration
![Page 70: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/70.jpg)
Gyorsító cső metszete
![Page 71: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/71.jpg)
Standing wave accelerator:
the RF energy reflected at both ends creating a standing wave.
The length of each cavities equal one-quarter wavelength.
Half of the cavities have zero field all times, they can be moved off the beam axis.(Shortened standing wave tube)
2. Accelerator Major Subsystems
structure - gantry.
RF source (magnetron or klystron), modulator, circulator, waveguides, electron gun, AFC system, cooling system, gas system, vacuum system,
treatment head: bending magnet, target, primary collimmator, flattening filter, monitor chamber, secondary collimator.
![Page 72: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/72.jpg)
Generation of a standing wave
![Page 73: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/73.jpg)
Standing wave acceleration
![Page 74: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/74.jpg)
Shortened standing wave tube
![Page 75: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/75.jpg)
Shortened standing wave tube
![Page 76: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/76.jpg)
Shortened tube
![Page 77: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/77.jpg)
3. Multi-Leaf-Collimators (MLCs)
In clinical radiotherapy it is often necessary to produce irregular shaped fields.
Two possibilities: beam shaping with blocks
use of multi-leaf-collimators (MLCs)
Integrated MLCs:
medium size and large fields (up to 40x40 cm2)
Accessory MLCs: e.g.for stereotactic conformal therapy, micro-MLCs, small fields (10x10 cm2)
![Page 78: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/78.jpg)
Integrated MLC
![Page 79: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/79.jpg)
Accessory type micro-MLC
![Page 80: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/80.jpg)
Accessory type micro-MLC
![Page 81: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/81.jpg)
Accessory type micro-MLC
![Page 82: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/82.jpg)
Beam shaping with micro-MLC
![Page 83: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/83.jpg)
Important features
Maximum field size – 40x40 cm2, 10x10 cm2
Leaf resolution (leaf width) – 1 cm, 2-3 mm
Maximum overtravel
How far a leaf can be moved over the midline
Operating modes
Static: Dynamic:
Focusing properties and penumbra
![Page 84: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/84.jpg)
MLC in static mode
![Page 85: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/85.jpg)
MLC in dynamic mode
![Page 86: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/86.jpg)
B. Treatment Procedures
(conformal therapy)
1. Convencional (classical) conformal RT
The basic problem:
- PDD is an exponential decreasing function of depth. The dose is higher close to the surface than at the depth of tumor.
The solution:
- using more fields
- to tailor the beams to the shape of target volume.
the conformity of dose distribution can be increased.
Conformity:
- a 3D dose distribution should follow the tumor shape while sparing the OARs.
![Page 87: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/87.jpg)
Four-field treatment technic
![Page 88: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/88.jpg)
How can be conformity increased?
Higher number of beams
Optimization of beam directions
Optimization of beam energy (photons))
Application of a MLC.
Smaller leaf width.
More than one target point.
Moving bean irradiations.
The Limits of Conventional Conformal RT.
Conformal and homogeneous dose distribution cannot be obtained in all cases.
-Difficult to find good directions.
-Beam overlap in the case of high number of beams.
![Page 89: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/89.jpg)
Micro-MLC
![Page 90: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/90.jpg)
Tumor and OARs
![Page 91: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/91.jpg)
Multifield radiation
![Page 92: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/92.jpg)
2. Intensity Modulated Radiation Therapy (IMRT)
Solution: IMRT-technique.
Basis: generation of intensity modulated fields and to treat with these fields.
(Fig. Shows a beam arrangement with seven IMFs).
How to deliver these fields?
Step-and-Shoot technique (superposition of irregurarly shaped and partial overlapping field components.)
Sliding Window technique, or dynamic MLC(independently moving leaves during radiation)
Physical Compensators (absorbing material)
![Page 93: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/93.jpg)
The principle of IMRT
![Page 94: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/94.jpg)
Intensity modulated fields
![Page 95: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/95.jpg)
Step-and-Shoot technique
![Page 96: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/96.jpg)
Dynamic MLC technique
![Page 97: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/97.jpg)
a, Step-and-Shoot technique
(static, Bortfeld-Boyer technique)
Generally an IMF is the superposition of irregularly shaped and partial overlapping field components.
Terms: intensity map, channel, intensity level, field component (subfield, segment)
Close-in technique
Sweep technique
Close-in: leaves are moving in both directions
Sweep: leaves are moving in one direction only
![Page 98: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/98.jpg)
Step-and-Shoot Close-in technique
![Page 99: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/99.jpg)
Technical terms
in IMRT
![Page 100: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/100.jpg)
Step-and-Shoot Close-in technique
![Page 101: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/101.jpg)
Step-and-Shoot Close-in technique
One leaf pair
![Page 102: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/102.jpg)
Step-and-Shoot Sweep technique
![Page 103: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/103.jpg)
Step-and-Shoot Sweep technique
![Page 104: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/104.jpg)
Step-and-Shoot Sweep technique
One leaf pair
![Page 105: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/105.jpg)
Step-and-Shoot Close-in and Sweep technique
![Page 106: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/106.jpg)
b, The Dynamic Technique
An analog-limiting case of the sweep technique, called sliding window technique.
Leaf position accuracy is very important.
Shorter treatment time High complexity
No problems with low dose fields Verification too.
c, Physical compensators
Compensator: an absorbing material with variable thickness. The prescribed intensity is produced
by the thickness of the matter.
+ −
![Page 107: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/107.jpg)
Dynamic IMRT technique
![Page 108: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/108.jpg)
Small positioning error– large dose error
![Page 109: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/109.jpg)
Physical
compensator
![Page 110: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/110.jpg)
Physical compensator
![Page 111: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/111.jpg)
Some specifics:
- Every intensity map – individual compensator (labour intensive)
- Divergence - layers
- High spatial resolution.
- Faster, than the step-and-shoot. (treatament time)
- IMFs without MLC.
- Mold material.
![Page 112: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/112.jpg)
VII. Clinical Radiation Dosimetry
1. Principles
Definition of Dose: the absorbed dose is the energy absorbed in the dm mass element divided by the dm.
Clinical dosimetry, water absorbed dose to water
Radiation types and fields:
wave or particle
Two types of radiations play a major role in radiology.
- photons: X-rays or gamma rays, with energies in the range of keV and higher. Zero rest mass.
- electrons: they have a rest mass and a negative charge. Electron states or nucleus transition (beta-rays)
(Gy – Gray)
![Page 113: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/113.jpg)
Radiation field: a part of the space where rays or particles are moving.
Flux density: the number of particles which cross through a small perpendicular plane per unit time.
Energy Transfer by Photons and Electrons
Photons: - photoelectric effect
- Compton effect
- Pair production
These interaction processes release secondary electrons, which again interact with the matter.
Electrons: - collisions with the atoms or electrons.
- radiative processes (Bremsstrahlung production)
Inelastic collisions with the electrons in the atomic shell lead to excitation and ionization of the atom.
![Page 114: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/114.jpg)
Photoelectric effect
![Page 115: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/115.jpg)
Compton effect
![Page 116: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/116.jpg)
Pair production
![Page 117: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/117.jpg)
2. Measurement of Dose
A variety of physical and chemical effects can be used.
Ionization in gas ionization chamber
proportional counter
Geiger-Müller counter
Ionization in solid semiconductor crystal
Luminescence TLD
Chemical effects photografic film
chemical dosimeter
Thermal effects calorimeter
![Page 118: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/118.jpg)
Absolute Measurement
Farmer-type ionization chamber + water phantom
1. Positioning 2. Connection 3. Measurement 4. Calculation 5. Corrections
1. Positioning
2. Connection
3. Measurement
4. Calculation
ND,w – calibration factor, SSDL ref. cond.
5. Corrections
k = kρ·ks ·kp ·kQ e.g.
Relative dose measurement
![Page 119: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/119.jpg)
Chamber positioning in water phantom
![Page 120: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/120.jpg)
Connection to the electrometer
![Page 121: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/121.jpg)
Measurement with the electrometer
![Page 122: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/122.jpg)
Control source for density correction
![Page 123: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/123.jpg)
Air density correction
![Page 124: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/124.jpg)
3. Phantoms
A measurement of absorbed dose is performed within an absorbing medium called phantom.
Standard phantoms
Water phantom: TBA (Therapy Beam Analyzer)
Anatomical phantoms: Alderson-Rando phantom
IMRT phantoms
4. Dose verification
A dose verification test is required to guarantee, that the radiation applied to the patient is exactly the same as simulated and calculated by the computer.
Steps of the verification:
a, Virtual treatment of an appropriate phantom (plan transfer to the phantom, calculation, dose distr.)
b, Irradiation of the phantom measurement
c, Comparison of the calc. and meas. results.
![Page 125: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/125.jpg)
Standard phantom
![Page 126: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/126.jpg)
Water phantom
![Page 127: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/127.jpg)
Alderson-Rando phantom
![Page 128: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/128.jpg)
IMRT phantom
![Page 129: ATTENTION! The wholecontentof thelecturewithallthe ... · ATTENTION! The wholecontentof thelecturewithallthe animationscanbe dowloadedfrom: ... (ICRU 50, ICRU 62) GTV (Gross Tumor](https://reader033.fdocuments.us/reader033/viewer/2022041914/5e68a70327df374462378c19/html5/thumbnails/129.jpg)
Comparison of plan and measurement