Physical-technical quality assurance in radiotherapy - proposals for the testing of the total treatment system

Due to the increasingly complex structure of modern radiotherapeutic processes, the provisions governing the quality assurance inspection no longer reflect all the key physical-technical aspects of the treatment procedure. This is both because of ambiguities in determining what is actually part of the radiotherapy system in the interest of testing, and because of unclear or nonexistent regulations regarding to which provisions should be applied to which components in the testing. Furthermore, some standards no longer reflect the state of the art. For this reason, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) requested the SSK to identify existing gaps in the technical inspections of the qualified experts and formulate new requirements.

In this context, the SSK adopted the following recommendations in its 241st meeting on 28/29 April 2010:

1. In a networked system, the tests must be conducted for both the total system and for its separate components as well. Therefore an integrated physical-technical testing, particularly of the dosimetry in the total system, should be introduced within the next two years. For all relevant systems, rules on transfer of data from the imaging equipment used for treatment planning to the irradiation devices must be stipulated within one year.
2. Since there are currently no binding tolerance values for dosimetric or geometric uncertainty, either of the individual components or the total system, the Commission advocates establishing a working group consisting of physicists and physicians to work on laying down manufacturer-independent tolerance levels in radiotherapy which relate to the respective therapeutic measure.
3. Because treatment planning and dosimetry systems are closely linked to radiotherapy equipment components, and in light of their importance for the success of the therapy, both systems should be included in the quality assurance testing. In the same way, other systems which support radiotherapy must be incorporated into the quality assurance concept for the total system.
4. Specifications on comprehensive quality assurance for radiotherapy treatment planning systems must be elaborated.
5. If algorithms used in the radiotherapy treatment planning systems lead to significant deviations between the results of calculation and measurement, the limitations arising from these deviations should be communicated to the users in an appropriate form, also indicating the parameters applied.
6. The SSK suggests modifying DIN standard EN 61223-2-6 (constancy test of CT equipment) to the requirements of radiotherapy.
7. The inspection of the individual components for Intensity Modulated Radiation Therapy (IMRT) should be based on DIN 6875-3.