The document discusses the commissioning and quality assurance procedures needed for radiation treatment planning systems, including performing various dose calculation and distribution tests on photon and electron beams to validate the system is working accurately before clinical use. It also describes the ongoing quality control checks that should be done such as reproducibility tests, plan verification, and in vivo dosimetry to ensure continued safe and proper system performance. Commissioning a new system typically takes months while quality assurance should involve trained staff spending about 20 minutes checking each patient's plan.

1. Radiation Protection in
Radiotherapy
Part 10
Good Practice including Radiation
Protection in EBT
Lecture 3 (cont.): Radiotherapy Treatment Planning
IAEA Training Material on Radiation Protection in Radiotherapy

2. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 2
C. Commissioning
 Complex procedure depending very much on
equipment
 Protocols exist and should be followed
 Useful literature:
 J van Dyk et al. 1993 Commissioning and QA of treatment
planning computers. Int. J. Radiat. Oncol. Biol. Phys. 26: 261-273
 J van Dyk et al, 1999 Computerised radiation treatment planning
systems. In: Modern Technology of Radiation Oncology (Ed.: J
Van Dyk) Chapter 8. Medical Physics Publishing, Wisconsin,
ISBN 0-944838-38-3, pp. 231-286.

3. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 3
Acceptance testing and
commissioning
Acceptance testing: Check that the system conforms with
specifications.
 Documentation of specifications either in the tender, in
guidelines or manufacturers’ notes – may test against
standard data (e.g. Miller et al. 1995, AAPM report 55)
 Subset of commissioning procedure
 Takes typically two weeks
Commissioning: Getting the system ready for clinical use
 Takes typically several months for modern 3D system

4. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 4
Some equipment required
 Scanning beam data acquisition system
 Calibrated ionization chamber
 Slab phantom including
inhomogeneities
 Radiographic film
 Anthropomorphic phantom
 Ruler, spirit level

5. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 5
Commissioning
A. Non-dose related components
B. Photon dose calculations
C. Electron dose calculations
(D. Brachytherapy - covered in part 11)
E. Data transfer
F. Special procedures

6. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 6
A. Non-dose components
 Image input
 Geometry and scaling of
 Digitizer,
 Scans
 Output
 Text information
 Anatomical structure information
 CT numbers
 Structures (outlining tools, non-axial
reconstruction, “capping”,…)

7. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 7
Electron and photon beams
 Description (machine, modality, energy)
 Geometry (Gantry, collimator, table,
arcs)
 Field definition (Collimator, trays, MLC,
applicators, …)
 Beam modifiers (Wedges, dynamic
wedges, compensators, bolus,…)
 Normalization

8. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 9
B. Photon calculation tests
 Point doses
 TAR, TPR, PDD, PSF
 Square, rectangular and irregular fields
 Inverse square law
 Attenuation factors (trays, wedges,…)
 Output factors
 Machine settings

9. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 10
Photon calculation tests (cont.)
 Dose distribution
 Homogenous
 Profiles (open and wedged)
 SSD/SAD
 Contour correction
 Blocks, MLC, asymmetric jaws
 Multiple beams
 Arcs
 Off axis (open and wedged)
 Collimator/couch rotation
PTW waterphantom

10. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 11
Photon calculation tests (cont.)
 Dose distribution
 Inhomogeneous
 Slab geometry
 Other geometries
 Anthropomorphic phantom
 In vivo dosimetry at least for the
first patients
 Following the incident in Panama, the IAEA
recommends a largely extended in vivo dosimetry
program to be implemented

11. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 12
C. Electron calculation
 Similar to photons, however, additional:
 Bremsstrahlung tail
 Small field sizes require special consideration
 Inhomogeneity has more impact
 It is possible to use reference data for
comparison (Shui et al. 1992 “Verification
data for electron beam dose algorithms” Med.
Phys. 19: 623-636)

12. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 13
E. Data transfer
 Pixel values, CT numbers
 Missing lines
 Patient/scan information
 Orientation
 Distortion, magnification
All needs verification!!!

13. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 14
F. Special procedures
 Junctions
 Electron abutting
 Stereotactic procedures
 Small field procedures (e.g. for eye
treatment)
 IMRT
 TBI, TBSI
 Intraoperative radiotherapy

14. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 15
Sources of uncertainty
 Patient localization
 Imaging (resolution, distortions,…)
 Definition of anatomy (outlines,…)
 Beam geometry
 Dose calculation
 Dose display and plan evaluation
 Plan implementation

15. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 16
Typical accuracy required (examples)
 Square field CAX:
1%
 MLC penumbra: 3%
 Wedge outer beam:
5%
 Buildup-region: 30%
 3D inhomogeneity
CAX: 5%
From AAPM TG53

16. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 17
Typical accuracy required (examples)
 Square field CAX:
1%
 MLC penumbra: 3%
 Wedge outer beam:
5%
 Buildup-region: 30%
 3D inhomogeneity
CAX: 5%
Note:
Uncertainties have
two components:
Dose (given in %)
Location (given in
mm)

17. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 18
Time and staff requirements for
commissioning (J Van Dyk 1999)
 Photon beam: 4-7 days
 Electron beam: 3-5 days
 Brachytherapy: 1 day per source type
 Monitor unit calculation: 0.3 days per
beam

18. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 19
Some ‘tricky’ issues
 Dose Volume Histograms - watch sampling,
grid, volume determination, normalization
(1% volume represents still > 10E7 cells!)
 Biological parameters - Tumour Control
Probability (TCP) and Normal Tissue
Complication Probability (NTCP) depend on
the model used and the parameters which
are available.

19. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 20
Commissioning summary
 Probably the most complex task for RT
physicists - takes considerable time and training
 Partial commissioning needed for system
upgrades and modification
 Documentation and hardcopy data must be
included
 Training is essential and courses are available
 Independent check highly recommended

20. Quick Question:
What ‘commissioning’ needs to be done for a hand
calculation method of treatment times for a superficial
X Ray treatment unit?

21. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 22
Superficial beam
 HVL
 Percentage depth dose (may be look up table)
 Normalization point (typically the surface)
 Scatter (typically back scatter) factor
 Applicator and/or cone factor
 Timer accuracy
 On/off effect
 Other effects which may affect dose (e.g. electron
contamination)

22. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 23
Quality Assurance of a treatment
planning system
 QA is typically a subset of commissioning
tests
 Protocols:
 As for commissioning and:
 M Millar et al. 1997 ACPSEM position paper.
Australas. Phys. Eng. Sci. Med. 20 Supplement
 B Fraas et al. 1998 AAPM Task Group 53: QA for
clinical RT planning. Med. Phys. 25: 1773-1829

23. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 24
Aspects of QA (compare also
part 12 of the course)
 Training - qualified staff
 Checks against a benchmark -
reproducibility
 Treatment verification
 QA administration
 Communication
 Documentation
 Awareness of procedures required

24. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 25
Quality Assurance

25. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 26
Quality Assurance
Check prescription
Hand calculation of
treatment time

26. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 27
Frequency of tests for planning (and
suggested acceptance criteria)
 Commissioning and significant upgrades
 See above
 Annual:
 MU calculation (2%)
 Reference plan set (2% or 2mm)
 Scaling/geometry input/output devices (1mm)
 Monthly
 Check sum
 Some reference test sets

27. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 28
Frequency of tests (cont.)
 Weekly
 Input/output devices
 Each time system is turned on
 Check sum (no change)
 Each plan
 CT transfer - orientation?
 Monitor units - independent check
 Verify input parameters (field size, energy, etc.)

28. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 29
Treatment planning QA summary
 Training most essential
 Staying alert is part of QA
 Documentation and reporting necessary
 Treatment verification in vivo can play
an important role

29. Quick Question:
How much time should be spent on treatment
planning QC?

30. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 31
Staff and time requirements
(source J. Van Dyk et al. 1999)
 Reproducibility tests/QC: 1 week per
year
 In vivo dosimetry: about 1 hour per
patient - aim for about 10% of patients
 Manual check of plans and monitor
units: 20 minutes per plan

31. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 32
QA in treatment planning
The planning system
QA of the system
Plan of a patient
QA of the plan

32. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 33
QC of treatment plans
 Treatment plan:
Documentation of
 treatment set-up,
 machine parameters,
 calculation details,
 dose distribution,
 patient information,
 record and verify
data
 Consists typically of:
 Treatment sheet
 Isodose plan
 Record and Verify
entry
 Reference films
(simulator, DRR)

33. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 34
QC of treatment plans
 Check plan for each patient prior to
commencement of treatment
 Plan must be
 Complete from prescription to set-up
information and dose delivery advise
 Understandable by colleagues
 Document treatment for future use

34. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 35
Who should do it?
 Treatment sheet checking should involve
senior staff
 It is an advantage if different professions
can be involved in the process
 Reports must go to clinicians and the
relevant QA committee

35. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 36
Example for physics treatment sheet
checking procedure
1. Check prescription (energy/dose/fractionation is everything signed ?)
2. Check prescription and calculation page for consistency: Isocentric (SAD) or fixed distance (SSD) set-up ? Are all
necessary factors used? Check both,dose/fraction and number of fractions.
3. Check normalisation value (Plan or data sheets).
4. Check outline, separation and prescription depth.
5. Turn to treatment plan: Does it look ok ? Outline ? Bolus ? Isocentre placement and normalisation point ? Any concerns
regarding the use of algorithms near surfaces or inhomogeneities? Would you expect problems in planes not shown ?
Prescription ?
6. Check and compare with treatment sheet calculation page: treatment unit and type, field names, weighting, wedges,
blocks, field size (FS), focus surface distance (FSD), Tissue Air Ratio (TAR) (if isocentric treatment) - is this consistent
with entries in treatment log page?
7. Electrons only: …
8. Photons only: …
9. Check shadow tray factor, wedge factor. Are any other attenuation factors required (e.g. couch, headrest, table tray...) ?
10. Check inverse square law factor (in electron treatments: is the virtual FSD appropriate?)
11. Calculate monitor units. Is time entry ok ?
12. Check if critical organ (e.g. spinal cord, lens, scrotum) dose or hot spot dose is required. If so, is it calculated correctly ?
13. Suggest in vivo dosimetry measurements if appropriate. Sign calculation sheet (if everything is ok).
14. Compare results on calculation page with entries in treatment log.
15. Check diagram and/or set up description: is there anything else worth to consider ?
16. Sign top of treatment sheet (specify what parts where checked if not all fields were checked).
17. Contact planning staff if required. Sign off physics log book.

36. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 37
Example for physics treatment sheet
checking procedure
1. Check prescription (energy/dose/fractionation is
everything signed ?)
2. Check prescription and calculation page for
consistency: Isocentric (SAD) or fixed distance (SSD)
set-up ? Are all necessary factors used? Check
both,dose/fraction and number of fractions.
3. Check normalisation value (Plan or data sheets).
4. Check outline, separation and prescription depth.
5. Turn to treatment plan: Does it look ok ? Outline ?
Bolus ? Isocentre placement and normalisation point ?
Any concerns regarding the use of algorithms near
surfaces or inhomogeneities? Would you expect
problems in planes not shown ? Prescription ?

37. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 38
Example for physics treatment sheet
checking procedure (cont.)
6. Check and compare with treatment sheet calculation page:
treatment unit and type, field names, weighting, wedges,
blocks, field size (FS), focus surface distance (FSD), Tissue
Air Ratio (TAR) (if isocentric treatment) - is this consistent with
entries in treatment log page?
7. Electrons only: …
8. Photons only: …
9. Check shadow tray factor, wedge factor. Are any other
attenuation factors required (e.g. couch, headrest, table
tray...) ?
10. Check inverse square law factor (in electron treatments: is the
virtual FSD appropriate?)
11. Calculate monitor units. Is time entry ok ?
12. Check if critical organ (e.g. spinal cord, lens, scrotum) dose or
hot spot dose is required. If so, is it calculated correctly ?

38. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 39
Example for physics treatment sheet
checking procedure (cont.)
13. Suggest in vivo dosimetry measurements if
appropriate. Sign calculation sheet (if everything is
ok).
14. Compare results on calculation page with entries in
treatment log.
15. Check diagram and/or set up description: is there
anything else worth to consider ?
16. Sign top of treatment sheet (specify what parts
where checked if not all fields were checked).
17. Contact planning staff if required. Sign off
physics log book.

39. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 40
Treatment plan QA summary
 Essential part of departmental QA
 Part of patient records
 Multidisciplinary approach

40. Quick Question:
What advantages has a multidisciplinary
approach to QC of treatment plans?

41. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 42
Did we achieve the objectives?
 Understand the general principles of
radiotherapy treatment planning
 Appreciate different dose calculation
algorithms
 Be able to apply the concepts of optimization
of medical exposure throughout the treatment
planning process
 Appreciate the need for quality assurance in
radiotherapy treatment planning

42. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 43
Overall Summary
 Treatment planning is the most important step
towards radiotherapy for individual patients -
as such it is essential for patient protection as
outlined in BSS
 Treatment planning is growing more complex
and time consuming
 Understanding of the process is essential
 QA of all aspects is essential

43. Any questions?

44. Question:
Please label and discuss the following processes in
external beam radiotherapy treatment.

45. Radiation Protection in Radiotherapy Part 10, lecture 3 (cont.): Radiotherapy treatment planning 46
Question:
Patient
Treatment unit
Diagnostic tools
Treatment
planning
1
3
5
4 2
6