In this section the detailed description of the audit service based on end-to-end testing (E2E) is provided. The service consists of:
- Offsite preparation by MedAustron:
- Design of E2E Tests in discussion with the Proton Center
- Communication of necessary information to the Proton Center:
- Description of the phantoms for each E2E Test (shape, dimensions, weight, etc.)
- Description of target, dose constraints (if applicable), dose prescription and planning constraints for each E2E test
- Description of the dosimetry techniques used for the E2E tests.
- Delivery of phantoms and equipment > Read more
- Calibration and QA of alanine pellets in high-energy proton beam.
- Calibration and QA of EBT3 films in high-energy proton beam.
- Communication of tasks by MedAustron to be performed by the Proton Center and where necessary with support from a Medical Physicist employed by the Proton Center:
- CT imaging of the phantoms according to local procedures
- Planning of prescription for each selected E2E test according to local procedures
- Phantom immobilization, alignment and positioning according to local procedures
- Delivery of the planned beam delivery sequence according to local procedures
- Onsite support and onsite activities for max. 4 working days by a Medical Physicist employed by MedAustron:
- Onsite support with CT imaging of the phantoms, planning of prescription and phantom immobilization, alignment and positioning
- Loading and unloading of alanine pellets and radiochromic film in the phantom inserts and phantom assembly and disassembly
- Shipment of alanine pellets to NPL (UK) for readout.
- Evaluation of ion recombination and polarity behavior for MedAustron’s ionization chamber assembly (Farmer ionization chamber, cables and electrometer) at the Proton Center beam quality.
- Absorbed dose to water determination for each E2E test using MedAustron’s ionization chamber assembly (Farmer ionization chamber, cables and electrometer) calibrated in terms of absorbed dose to water at NPL.
- Post-processing and analysis of data by MedAustron
- Provision of a final audit report containing:
- Description of the methods of the audit and the measurement equipment used
- Description of the phantom, target, constraints (if applicable) and dose prescription for each E2E test performed
- NPL certificate containing:
- Co-60 equivalent absorbed dose to water values for each alanine pellet according to Accredited Radiotherapy Level Alanine Dosimetry service
- Absorbed dose to water values for each alanine pellet corrected for high-energy proton response as measured by MedAustron
- Corrections of the alanine pellets’ measurements provided by NPL for the proton energy dependence.
- Measurement results and comparison with prescribed absorbed dose to water values.
- For each E2E test, results for 22 alanine pellet positions and for one point measurement with Farmer ionization chamber are reported.
- Uncertainty budget of measurement results.
Interested institutions should send a request to MedAustron for the audit and fill a questionnaire. The purpose of the questionnaire is two-fold: (i) to collect information on the features of the beam delivery system, reference beam calibration and treatment planning system features at the proton facility and (ii) to outline the scope of E2E tests for dosimetry auditing (e.g. amount of tests, selection of phantoms, beam arrangements for each test). Further steps in the realization of the E2E test auditing procedure are based on the completed questionnaire and requested scope of E2E tests for dosimetry auditing. The contractual agreement aligned with the requested scope will be offered to the institution for further consideration.