The EURAMET Technical Committee for ionising radiation (TC-IR)
Roadmap for 2020:
TC-IR Roadmap
Dosimetry and Radionuclides in Health Care (Jacco de Pooter, VSL and Jean-Marc Bordy, LNHB)
a. Medical applications
i. Verification of dose planning and treatment for external beam therapy.
ii. Measuring quantities and dosimetry for small fields
iii. Individualised dose planning and treatment for targeted radionuclide therapy
iv. Biological target volume
v. Dosimetry protocols for new modalities using a variety of energies and radiation type
vi. Medical information from X-ray, CT and nuclear medicine imaging ↔ optimisation of dose/quality information of imaging and combined imaging/treatment
vii. Quantity and metrology for late effects and secondary cancers
viii. Development of enhanced dosimetry techniques required for the radiation sterilization of novel medical devices and combination products containing active pharmaceutical and biological components
b. Neutron dosimetry (especially for hadron therapy and BNCT)
c. Occupational dosimetry in mixed beta photon radiation fields, dosemeters and measuring quantities and calibration procedure for H’(0.07) Hp(0.07), H’(3) and Hp(3).
Drivers and Challenges
The last decades the application of ionising radiation based techniques in healthcare has evolved considerably allowing for advanced diagnostic and therapeutic modalities. The therapeutic application is dominated by external beam radiotherapy applied in the treatment of cancer. Currently, there are about 4 million new cases of cancer in Europe per year. These figures are predicted to increase in the future due to the improvement of diagnostic methods and the global ageing of the population in Europe. About 75% of cases are treated using radiotherapy (alone or with chemotherapy and/or surgery), it is estimated that about 50% of successful treatments can be attributed to radiotherapy. Recently developed treatment modalities and new irradiation facilities may lead to a further increase of the use radiotherapy techniques.
Advancing technology has enabled the introduction of complex forms of radiotherapy in the treatment of cancer, in which dose is delivered in ways that are far removed from established reference dosimetry. While treated volumes can now conform closely to the defined target, so reducing damage to surrounding normal tissue, the accuracy with which the dose is delivered may fall short of the requirements given by ICRU Report 24. These methodologies raise metrological problems for which (i) the traceability of tumour doses to primary standards and (ii) the validation of the treatment plans have to be demonstrated. It is expected that this development continues to enable better targeting of the tumor with a reduced dose to the healthy tissue. This will be accomplished by online imaging techniques (CT, MRI), using types of radiation (protons, carbons) with better physical properties and highly focused dose distributions delivered by rotational radiotherapy, novel brachytherapy sources and robotic techniques. New dosimetric techniques are needed to bridge the gap between the dosimetry for these new techniques and the currently applied reference dosimetry.
Next to external beam radiotherapy also other techniques such as targeted radionuclide therapy (TRT) is increasing and evolving. For targeted radionuclide therapy no standardized dosimetric techniques are available.
For diagnostic applications the use of practical quantities such as CDTI, CK required to study dedicated references. This point is very important taking into account the patient’s doses dues to the very large number of diagnostic exams, more than 1 per person per year on average, in developed countries.
New compact facilities for proton therapy are studied which will lead to increase the use of the treatment modalities based on these particles. The use of such particles raised the question of the patient’s neutrons doses resulting of the hadron interaction with tissues. Dedicated methods for measuring or evaluating the neutrons doses are necessary. Whatever is the treatment modality, it is necessary to define which quantity has to be used to report neutron “doses” for patient in order to harmonize these practices so that to facilitate comparison between treatments in terms of side effects.
Recently eye lens doses have received a lot of attention because of some epidemiological studies showing that the threshold dose for cataract induction, if there is one, could be lower than that assumed. Therefore, ICRP issued a “Statement on Tissue Reaction” including a revision of the eye lens limit (Paragraph 3) that lowers the annual limit to 20 mSv. On the other hand, the operational quantity for eye lens,Hp(3), is not usually monitored.
The ORAMED project has proposed an overall procedure for a correct eye lens dose assessment, the construction of a dedicated dosemeter prototype, the better suited calibration phantoms cheap and easy to build and the definition of an adequate procedure for type test and calibration of eye lens dosemeters. The Air kerma to Hp(3) conversion coefficients (CCs) for monoenergetic photons and electrons have been published by ENEA and CEA LNHB. The new ORAMED procedure better matches these new anthropomorphic model HT(eye lens) data published by PTB.
Although, the use of such a new procedure enables by the standards, have to be improved and generalised in the light of the workplace situation. More generally, the calculations of CCs for Hp(3) raised questions of their calculation method for all the operational quantities (Hp, H’, H*). In the past kerma approximation was always used and lead to large discrepancies with protection quantities for energies where electronic equilibrium is not reached.
Targets
Improved metrology will lead to sustained improvements of patients’ Quality of Life by achieving a higher cure rate while reducing the side effects (second cancer risks and physiological effects). In addition it will facilitate faster clinical dissemination of new radiotherapy techniques.
Safe working environment for European workers.
Improved metrology for diagnostic equipment will lower the radiation burden to the European citizen by improved optimisation of dose and image quality.
Deliverables
To achieve these targets the following deliverables are needed
i. Verification of dose planning and treatment for external beam therapy.
ii. Measuring quantities and dosimetry for small fields
iii. Individualised dose planning and treatment for targeted radionuclide therapy
iv. Biological target volume
v. Dosimetry protocols for new modalities using a variety of energies and radiation type
vi. Medical information from X-ray, CT and nuclear medicine imaging ↔ optimisation of dose/quality information of imaging and
vii. Standardized dosimetry for combined therapy and (online) imaging systems (using CT, MRI)
viii. Quantity and metrology for late effects and secondary cancers
ix. Development of enhanced dosimetry techniques required for the radiation sterilization of novel medical devices and combination products containing active pharmaceutical and biological components
x. Quantities for neutron dosimetry should be adapted to therapy.
xi. Traceability for dose estimations of workers. Derive Conversion coefficient from air kerma into H’(3) for photons. Verification, for electrons, that H’(3) could be estimated by for HP(10).
Technologies
New primary standards for new treatment modalities.
Development of new instruments (dosimeters, phantoms …) , dose reconstruction systems, and traceability.
Nuclear imaging applied to dose planning for TRT verified by phantom measurements.
Development of Biological and Functional Imaging techniques.
Methods and measurement protocols for neutron dosimetry in radiotherapy.
Enabling Science
Monte-Carlo simulation of radiation transport
Detector modelling
Primary standards
If you want more information please contact the roadmap pilot or TC-IR Chair.