Postal Beam Output Audit (BOA) for Radiotherapy
Aims and Scope
Proficiency Tests (PT) give participants the opportunity to demonstrate technical competence, meet accreditation requirements, and/ or gain confidence by comparing their results with those of other laboratories or radiotherapy hospitals. They also provide independent insight into measurement performance, strengthen quality systems, and support risk management in line with ISO/IEC 17025:2017.
Each PT consists of a postal beam output audit focused on reference dosimetry in 4 clinical photon beams of the participant’s choice (6 MV – 18 MV, FFF and/ or is MRL possible), conducted in accordance with NCS-18, TRS-398, or equivalent internationally recognised protocols.
Criteria of Participation
Participation is open to any laboratory or radiotherapy hospital which is capable of performing reference dosimetry in terms of absorbed dose to water, Dw, in high-energy photon beams (Co-60 or 6 MV – 18 MV x-rays) according to internationally accepted Codes of Practice (e.g. NCS-18, TRS-398, TG-51, etc.).
Quantities to be Measured
Absorbed dose to water, Dw, in the unit gray (Gy), at 10 cm depth in clinical photon beams between 6 MV and 18 MV of the participating laboratory or radiotherapy hospital.
Travelling Standard
The traveling standard and equipment is a small full-scatter PMMA-phantom with radiochromic films. The phantom and films should be handled according to the instruction and with care.
Method and Equipment
Participants are advised to use their own methods and equipment for beam calibration before performing the irradiation of the phantom and films. These should be carried out in accordance with international Codes of Practice and within the scope of the laboratories or radiotherapy hospital usual practices.
Instructions and Protocol
VSL will provide the PT protocol before shipping the instruments. A report sheet will be provided by email to submit the results. The traveling equipment will contain a clear and concise instruction sheet. Each participant will have one week to perform the measurements and submit the results.
Schedule
This programme is organised as an ongoing proficiency test and will operate on a calendar year basis.
The proficiency test will start as soon as the participant has registered on the site. After registration. the specific date for the dosimetry audit will be determined in agreement with the participant. The equipment required for the PT will be delivered by courier to each participant. Each participant will have one week to perform irradiation of the phantom and detector and submit their results. The aim is to release the PT report no later than three weeks after return of the equipment to VSL. Detailed instructions and contact information will be provided.
Assigned Value
Reference values will be determined by VSL using traceable calibrated standards. These assigned values form the basis for evaluating each participant’s measurement results.
Performance Evaluation
The results will be evaluated using the normalized error (En-score).
Interpretation of the En-score is as follows:
|En| <= 1 Satisfactory performance
|En| > 1 Unsatisfactory performance
The final report presents results anonymously. Each laboratory can identify its own performance via a unique code. VSL guarantees full confidentiality and does not share individual data with third parties.
Deliverables
Upon completion of the PT, each participant will receive:
- An individual performance evaluation (3 weeks after return of the equipment);
- A detailed report with anonymized results (at the end of a calendar year or pre-defined period).
This report may serve as supporting evidence for accreditations, clinical trials and (internal) quality reviews.
Confidentiality Statement
VSL keeps all data regarding the performance of individual participants, or groups of participants, strictly confidential. Data is accordingly protected and stored in areas on networks with restricted access. The relationship between results and the laboratories that submitted them will never be disclosed. Only the laboratory is granted access to its performance through the assigned code number.
Transport
VSL will handle and cover the shipment of instruments to all participating laboratories. Each participant is responsible for performing the calibration work within the agreed time frame and submitting their results using the provided report sheet, in accordance with the protocol. Detailed shipping instructions and tracking information will be provided, with all logistics fully managed by VSL.
Payment Terms
Payment in advance, at least one month before the start.
Failure to pay on time may result in exclusion from participation, without any right to refund or compensation.
Participants
This proficiency test is open to any number of participants.