Additional imaging doses and associated risks in image-guided radiotherapy - Toward an optimized therapeutic approach – AID-IGRT

Image-guided radiotherapy (IGRT) and adaptive radiotherapy (ART) represents an indispensable, life-saving therapeutic approach against cancer, in the frame of predictive medicine. IGRT/ART treatment scenarios required multiple imaging sessions to define accurately the target volume and to monitor the treatment. These multiple imaging procedures are mainly based on X-ray imaging devices. The increased use of radiographic image guidance in IGRT/ART could lead to additional doses from 1 to 2 Gy. Today, these additional doses delivered to the patient, as well as their potential impact on mid- and long-term increase of health risks, are poorly estimated, reported and hence neglected. This is part of a major concern for public health, called imaging dose management, which deals with several initiatives worldwide to optimize doses due to diagnostic or positioning procedures, especially for children and young adults. The case of children and young adults is of particular importance because they are much more radiosensitive than adults and that X-ray imaging-induced doses could be responsible for extra morbidity and late side effects. In radiation oncology, there is no tool yet available in clinical routine for dose management, mainly because no legal obligation of reporting dose exists. However, scientific societies recommend the greatest caution for populations presenting higher risks.

This project aims at providing an integrated approach for imaging dose management of IGRT/ART treatments, in order to deploy them even more efficiently and safely. The different steps involved in dose management will be treated during this project. First of all, delivered doses have to be known as accurately as possible, and the main difficulty is that imaging protocols are varying a lot, depending on many parameters. Accurate dosimetric protocols will first be developed in order to measure organ doses using calibrated dosimeters on anthropomorphic phantoms representing a standard morphology of patient. Since our goal is to determine imaging doses on a patient-by-patient, organ-by-organ, and situation-by-situation, new Monte Carlo-based software will be then developed and commissioned against measurements. Finally, the concept of dose management in IGRT implies developing strategies for dose optimization. Among these strategies, the incorporation of imaging doses during the treatment planning process will be studied. Several problems have still posed before deploying this strategy in clinical routine. This project will help solving some of these problems, developing the main experimental and numerical tools necessary to dose management in IGRT/ART. Moreover, several routes to market will be explored during the project, in order to be able to propose to health professionals (medical physicists, clinicians) this tool under the most appropriate format for their use. This software will be the first of its generation, and will advantageously complete the portfolio of solutions and services offered by the Dosisoft firm, and help comforting them as a leader in Quality Assurance for radiotherapy.