Reviewing: S-RP-S1-2

External Beam Radiotherapy Techniques

Information:

Module information

Details

Title
External Beam Radiotherapy Techniques
Type
Specialist
Module code
S-RP-S1-2
Credits
20
Requirement
Compulsory

Aim of this module

To develop the knowledge and skills within external beam radiotherapy to enable the trainee to understand and critically assess their role as a Clinical Scientist in relation to external beam treatment equipment and treatment planning. From beam characterisation and data collection to treatment planning and verification and all the associated quality assurance.

Work-based content

Competencies

# Learning outcome Competency Action
# 1 Learning outcome 1,3 Competency

Take accurate measurements to characterise and calibrate a megavoltage photon beam

 Action View
# 2 Learning outcome 1,3 Competency

Take accurate measurements to characterise and calibrate an electron beam

 Action View
# 3 Learning outcome 3 Competency

Calibrate tertiary chambers and electrometers for MV photon and electron measurements

 Action View
# 4 Learning outcome 2,3 Competency

Perform routine quality assurance for a treatment unit and its associated imaging equipment

 Action View
# 5 Learning outcome 3,8 Competency

Audit the overall quality assurance programme for a treatment unit and assess whether the quality management system meets the requirements.  Report your findings and make recommendations

 Action View
# 6 Learning outcome 2,3 Competency

Perform routine quality assurance on a kV treatment unit

 Action View
# 7 Learning outcome 1,3 Competency

Perform output factor calculations and measurements for electron beams

 Action View
# 8 Learning outcome 2,3 Competency

Perform routine CT quality assurance

 Action View
# 9 Learning outcome 3,8 Competency

Audit local rules for a treatment unit

 Action View
# 10 Learning outcome 4 Competency

Review, assess and advise on the accuracy of a variety of different immobilisation techniques for different anatomical sites

 Action View
# 11 Learning outcome 5 Competency

Review the choice of pre-treatment imaging modalities for a selection of patients

 Action View
# 12 Learning outcome 3,5 Competency

Assess the clinical relevance of the CT and CBCT scanning protocols available for one anatomical site

 Action View
# 13 Learning outcome 5,6 Competency

Import patient CT scans into a treatment planning system and assess the relevant parameters for RT treatment planning

 Action View
# 14 Learning outcome 3,4,5,6 Competency

Outline treatment planning volumes on a TPS including external contours, OARs, PRVs, PTVs, planning volumes for a range of patients covering different anatomical sites

 Action View
# 15 Learning outcome 3,6,7 Competency

Produce and critically appraise routine treatment plans for a range of patients covering different anatomical sites

 Action View
# 16 Learning outcome 3,6,7 Competency

Perform checks required before clinical use of inverse and forward planned patient treatments including patient specific quality assurance where appropriate

 Action View
# 17 Learning outcome 3,6,7 Competency

Perform in vivo dosimetry, analyse and interpret results

 Action View
# 18 Learning outcome 3 Competency

Write, review or update the local risk assessment for patient dose verification

 Action View
# 19 Learning outcome 2,3,8 Competency

Participate in an external dosimetry audit, perform measurements and contribute to the report

 Action View

Assessments

Complete 4 Case-Based Discussions

Complete 4 DOPS or OCEs

Direct Observation of Practical Skills Titles

  • Produce and evaluate a simple treatment plan.
  • Measure the output of a linac.
  • Perform, analyse and critically assess cone beam image quality of quality assurance images.
  • Perform patient specific quality assurance and critically analyse the results.
  • Calibrate an ionisation chamber as per the code of practice (MV/kV/electrons).
  • Assist in the adjustment of linac beam parameters and discuss the implications for clinical use.
  • Perform required measurements to characterise an electron treatment beam.

Observed Clinical Event Titles

  • Discuss different external beam RT treatment plan options for a patient.
  • Discuss appropriate actions when accepting a treatment machine following technical intervention or repair by external/internal engineers.
  • Handover equipment to the clinical team after technical/physics intervention.
  • Identify and explain the advantages and shortcomings of treatment planning algorithms in routine use to another healthcare professional, for a variety of treatment sites.

Learning outcomes

# Learning outcome
1

Perform required measurements to characterise treatment beams.
2

Perform required measurements to establish a treatment machine is suitable for clinical use; interpret results and instigate corrective action where required.
3

Apply appropriate guidance, regulations and codes of practice to ensure patient safety in all elements of practice.
4

Identify appropriate immobilisation techniques to ensure accuracy of treatment delivery.
5

Explain and critically analyse the use of pre-treatment and on-treatment imaging within radiotherapy.
6

Develop and appraise external beam radiotherapy treatment plans for clinical use.
7

Practice effectively as part of a multidisciplinary team.
8

Perform audits in a variety of contexts and interpret their findings, disseminating information to others as appropriate.

Academic content (MSc in Clinical Science)

Important information

The academic parts of this module will be detailed and communicated to you by your university. Please contact them if you have questions regarding this module and its assessments. The module titles in your MSc may not be exactly identical to the work-based modules shown in the e-portfolio. Your modules will be aligned, however, to ensure that your academic and work-based learning are complimentary.

Learning outcomes

On successful completion of this module the trainee will be able to:

  1. Explain the physical principles of dose deposition and measurement, including the differences between interaction processes and their relative importance for radiotherapy treatment and imaging.
  2. Apply integrative knowledge of the fundamental theory and principles, of reference dosimetry, including selection of appropriate dosimetry equipment and the calibration chain.
  3. Describe the function and operation of radiotherapy equipment and technology, including linear accelerators, superficial and orthovoltage machines, imaging systems and associated dosimetry equipment.
  4. Justify the commissioning and quality assurance processes for radiotherapy equipment.
  5. Critically evaluate dose calculation algorithms, considering their limitations and uncertainties, the commissioning data required, and the appropriate check procedures.
  6. Critically appraise different treatment planning techniques, plan evaluation methodologies, and independent check philosophies.

Indicative content

Interactions
Directly ionising radiation Electron interaction processes, dose deposition and scattering, absorbed dose, Bragg-Gray cavity theory and limitations
Indirectly ionising radiation – MV energies Photon interaction processes (Compton, photoelectric, pair production), attenuation coefficients, fluence, CPE, KERMA and absorbed dose
Indirectly ionising radiation – kV energies

 

 Bremsstrahlung and characteristic radiation, exposure and absorbed dose in air, chamber design
Interaction processes in RT Relative importance of interaction processes, dependence on Z and E, effective Z
Equipment and treatment beams
Linear accelerators – photons Construction and operation, impact of changing various parameters, FFF beams, induced radioactivity, leakage
Linear accelerators – electrons Changing for photon to electron mode, virtual source distance applicators
Orthovoltage and superficial units Equipment construction and operation, filters, beam modification
Linac commissioning and quality assurance National and international guidance (e.g. IPEM, AAPM). Action limits and suspension levels.
In-room imaging equipment IGRT equipment, kV and MV imaging, CBCT and MVCT,  tracking / monitoring systems, optimisation
Beam data handling PDD/RDD/TPR/TMR, measurement and conversion, practical examples
Small fields

 

 Definition, measurement techniques and detectors, practical recommendations and guidance, codes of practice
Safety Safety systems, interlocks, servos
Radiation detectors and calibration chains
Ionisation detectors Relative vs. absolute measurement. Ionisation chamber construction, dosimetry and correction factors, clinical use
Radiation detectors Diodes, TLDs, film, gel, scintillators, alanine dosimetry, diamond detectors, portal imager
In vivo dosimetry Aims, techniques and equipment, advantages and limitations
Codes of practice National and international codes of practice for MV photons, electrons and kV including FFF, small fields and non-standard fields
Quality assurance of dose Interdepartmental audit. Definitive calibration. Intercomparison. Patient-specific quality assurance
Treatment planning
Clinical treatment planning algorithms Types of algorithm and their approximations/limitations, dependence on field size and energy, clinical use and examples
Patient preparation and immobilisation
Clinical RT treatment planning Options for planning common tumour sites e.g. prostate, lung, breast, auto-contouring algorithms and AI in treatment planning, automated planning
IMRT/VMAT

 

 Fixed gantry and rotational techniques, advantages and limitations, inverse planning algorithms, optimisation, knowledge-based planning, multi-criteria optimisation, ICRU83, treatment plan robustness, IMRT QA requirements

 
Imaging for RT planning Selection of imaging modality, requirements, synthetic CT
Modelling algorithms Mathematics of modelling, digital signal processing, superposition and convolution, Fourier transforms, beam modelling and validation
TPS commissioning Beam data requirements, choosing an appropriate detector, effects of data processing, beam modelling parameters, virtual patient representation, CT-to-ED curves, image manipulation, contouring and dose visualisation, DVH and dose statistics, plan metrics, data transfer, end to end testing, ongoing QC

 
Plan validation Independent MU calc and PSQA techniques, dose reporting, plan comparison and deliverability metrics
Validation calculations Monitor unit calculations for photons and electron beams, corrections for field size, SSD and inhomogeneity

Clinical experiences

Important information

Clinical experiential learning is the range of activities trainees may undertake in order to gain the experience and evidence to demonstrate their achievement of module competencies and assessments. The list is not definitive or mandatory, but training officers should ensure, as best training practice, that trainees gain as many of these clinical experiences as possible. They should be included in training plans, and once undertaken they should support the completion of module assessments and competencies within the e-portfolio.

Activities

  1. Attend a multidisciplinary team meeting and follow a patient’s progress through referral, immobilisation, pre-treatment imaging, planning and treatment.
  2. Attend pre-treatment imaging sessions and consider causes of errors and uncertainties.
  3. Observe treatment for patients for a range of different anatomical sites and techniques.
  4. Attend an on treatment review clinic to appreciate the impact of the treatment plan on the patient.
  5. Attend a patient information session to appreciate how information about radiotherapy is communicated to patients and patient’s concerns around their treatment.
  6. Attend a departmental meeting where service and quality improvement is discussed.
  7. Shadow a Clinical Scientific Computing healthcare professional working with radiotherapy to appreciate their role and input to the radiotherapy patient pathway.

Module assigned to

Specialties

Specialty code Specialty title View
Specialty code SPE1-1-26 Specialty title Radiotherapy Physics [2026] Action View
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