ESTRO 37 Abstract book

S125

ESTRO 37

measuring the breathing curve directly on the patient’s surface, surface scanners serve as ideal surrogates for robust and time efficient 4DCT scanning. As the user is free to select the spot on the patient’s surface, training and prior knowledge of the effects of choosing a region, which is not well correlated with internal tumor motion are vital to this application. There are multiple limitations in the use of optical surface scanning: For SBRT lung treatments for example, relying solely on surface information can lead to significant errors or uncertainties. So far, no vendor can provide updateable models for internal-external correlation of the patient’s surface and tumor motion, neither from surrogate or linac side. In general, surface guided radiation therapy has the capabilities of providing extra safety, improved accuracy, and giving the possibilities of implementing new radiation therapy techniques, while one must keep in mind, that an extra effort must be made always, such as additional training, QA procedures, and time expenses. SP-0246 Image Guided Adaptive RT: Challenges, pitfalls and opportunities using plan selection in daily clinical practice R. De Jong 1 1 Academic Medical Center, Radiation Oncology, Amsterdam, The Netherlands Abstract text Target volumes in the pelvic region (cervix, bladder and rectum) are prone to large deformations caused by daily variation in bladder and bowel filling. These deformations cannot be corrected by table shifts nor managed by drinking protocols and/or dietary instructions. Therefore, large population-based margins are necessary to compensate for these deformations. This makes sparing of the organs at risk (OAR) very challenging, even with the use of intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT). To overcome this problem, our department has implemented plan selection; a strategy using multiple pre-treatment plans tailored to a range of possible shape variations of the target volume that are patient specific. For cervix and bladder a full and empty bladder pre-treatment CT (or MRI) scan are used to generate the target volume structures covering the range of possible shape variations. For the rectum a full bladder CT is acquired and variable PTV margins are applied to create the set of treatment plans. Based on daily Cone Beam CT (CBCT) the best fitting plan is selected for the treatment. With this strategy PTV margins can be reduced significantly and thereby the dose to OARs, resulting in a risk reduction of toxicity without compromising target coverage. Despite these favourable aspects, plan selection has its challenges in daily clinical practice. Although plan selection uses a full and empty bladder CT scan to capture the range of motions of the target volume (cervix and bladder), those two CT scans remain a ‘snapshot’ of that particular moment and may not represent the real motion throughout the treatment. Moreover, selecting the best fitting plan at the treatment machine requires detailed knowledge of the target volume and relies on the image quality of the CBCT. This requires an intensive training of those responsible and may involve a shift in responsibilities for adequate use of plan selection. A clinical (protocolled) workflow of plan selection is thus required. Once a protocolled plan selection workflow is established in the department, it offers opportunities for target regions outside the pelvic region, for example, lung and oesophagus. In these regions deformations and displacement are rather unpredictable. Therefore, population based margins may be insufficient to account for the variation presented by certain patients and these patients may benefit from ad hoc plan selection. In this

lecture we will discuss the challenges and pitfalls of protocolled plan selection strategies in daily clinical practice. Additionally, we will demonstrate some ad hoc plan selection strategies outside the pelvic region.

Symposium: Modern learning methods

SP-0247 The educational offer of the ESTRO School: roadmap to choose the right course C. Verfaillie 1 1 ESTRO, Education and Science, Brussels, Belgium Abstract text The ESTRO School offers a wide range of educational opportunities to trainees and specialists in Radiation Oncology and associated professions. Around 35 live courses are conducted every year, in Europe and beyond. They address all professional and scientific needs of the radiation oncology community, based on the current core curricula. The School equally offers an annual program of live online contouring workshops (FALCON). Educational resources are made available through the ESTRO online library DOVE and the web-based platform Moodle has been implemented to enhance the learning experience of the live courses with permanent online access to learning material. The School also provides mobility grants for study visits to centers of excellence in Europe or beyond. A roadmap to all these activities is presented to familiarize (young) professionals with ESTRO’s educational portfolio. SP-0248 How to learn effectively? The role of modern learning methods in radiation oncology training (abstract by J.E. Bibault 1 ), M. Spalek 2 1 Université Paris Descartes - Hôpital Européen Georges Pompidou, Chef de Clinique Universitaire - Assistant Hospitalier en Oncologie Radiothérapie, Paris, France 2 The Maria Sklodowska-Curie Memorial Cancer Center, Warsaw, Poland Abstract text Radiation oncology is rapidly evolving in a multidisciplinary setting. Training has evolved from obtaining medical knowledge to the acquisition of skills and development of a professional attitude. Several tools are now available to learn radiation oncology: live, online or blended courses (ESTRO School) and workshops (FALCON), mobile apps, and social networks can all be leveraged to learn what makes a medical expert. In this presentation, we will highlight the best tools available. SP-0249 Experiences from young scientists: Participant ESTRO Physics Research Master Class M.L. Belli 1 1 Fondazione Centro San Raffaele, Deaprtment of Medical Physics, Milano, Italy Abstract text I am a young Medical Physics Expert, just finished my residency. During my residency, a part from a strong clinical involvement, I was actively involved in different research project and I had the opportunity to work with great experts in the field, both in my own country (Italy) as well as around Europe (i.e. Denmark, Belgium, Switzerland ). Now that I am working in a different institution as Medical Physics Expert, I am trying to pursue some research investigation and starting new projects. Even thought I am not at first-time investigator, I recognize that am still young in the field and that I need to discuss my projects with other researchers in order to be able to perform strong and valuable researcher