ESTRO 36 Abstract Book

S216 ESTRO 36 _______________________________________________________________________________________________

be related to poor treatment response. Thus, dose painting approaches have been proposed based on the hypothesis that local recurrence is related to resistant foci not eradicated by the currently prescribed doses, which might however be controlled by delivering non- homogeneous dose distributions targeting specific tumour phenotypes related to local control or risk of relapse after (chemo)radiotherapy. Clinical implementation of dose painting, however, is not a trivial task and the success cannot be guaranteed as there are several potential challenges and limitations related to the imaging techniques, the underlying radiobiological aspects and the current techniques for delivering the heterogeneous dose distributions. This talk will present a paradigm shift from focusing on the radiobiological dose prescription, such as in dose painting approaches, to biologically adapted radiation therapy, based on tumour responsiveness assessed with functional imaging. Thus, the general idea is to use functional information from advanced imaging modalities for the assessment of the tumour response early on during the course of the treatment followed by the adaptation of the treatment for the patients for which poor response is predicted. A previous study showing that the early response to treatment of NSCLC patients can be evaluated by stratifying the patients in good and poor responders based on calculations of the effective radiosensitivity derived from two FDG-PET scans taken before the treatment and during the second week of radiotherapy will be presented. Complementing studies on the feasibility of effective radiosensitivity calculations for H&N cancer patients as well as the identification of the optimal window during the treatment for assessing the effective radiosensitivity will also be presented. For the patient classified as poor responders, the distribution of the effective radiosensitivity displayed as a map of response overlapping onto the GTV could be used for guiding adaptive planning approaches. Thus, the method to be presented in this talk would allow the delineation of the sub-volumes expressing lack of response, hence the sub-volumes that should receive a dose boost as adaptive treatment based on functional imaging. Several strategies for treatment adaptation, including photon and proton irradiation, will be considered. This is an extremely novel approach to response assessment and treatment adaptation that opens the way for true treatment individualisation in radiation therapy. SP-0407 PET/CT artefacts for RT planning A. Santos 1 1 Hospital Cuf Descobertas- S.A., Nuclear Medicine Department, Lisboa, Portugal Nuclear Medicine, along with PET/CT technology has been playing an important role in the detection, staging and follow-up of lung cancer. The therapeutic approach to lung cancer can vary, depending on the staging of the tumour, being Radiotherapy one of the most important of the available treatments. The association of PET/CT to radiotherapy planning has a synergic effect that will benefit the patient. Nuclear Medicine Technologists (NMT) that perform PET/CT must be aware of the numerous artefacts and pitfalls that can influence the acquired images and the results of the diagnostic procedure. The equipment must have its quality standards assured, radiopharmacy aspects must be covered, the patient should be correctly prepared and also perform all stages of the procedure accordingly. Anyhow, artefacts and pitfalls can randomly occur and this is why it is so important to have theorical knowledge and practical skills in order to correctly identify the artefacts and correct it Symposium: Focus on lung cancer: What a radiotherapy department should offer their patients

when required. In addition, the active participation of the Radiotherapy technologists (RTT) in the multidisciplinary team surely increases the quality of the results. NMT benefit from the valuable inputs from RTT, since these professionals are specialists in radiotherapy patient positioning, and will be the common factor between PET/CT acquisition and radiotherapy treatment. Also, RTT commonly have a prior relation with the patient and this might play an important role in the patient welfare. The humanization of patient care, along with the state of the art of the technology, are the focus of the multidisciplinary team that surrounds the patient. SP-0408 ART in lung cancer: when and for whom? P. Berkovic 1 1 C.H.U. - Sart Tilman, Radiotherapy department, Liège, Belgium Lung cancer is the most common cause of cancer death worldwide [1]. Non-small cell lung cancer (NSCLC) accounts for 80 – 85% of all lung cancers of which about 30% are locally advanced (LA) at diagnosis [2]. Although concurrent chemoradiotherapy (cCRT) improves survival compared to sequential one (sCRT) [3], there remains room for improvement in the treatment of LA-NSCLC. Within the radiotherapy component, several possible treatment strategies were investigated, such as altered fractionation and/or dose escalation. However, dose escalation is severely hampered by normal tissue toxicity [4] and can lead to deleterious results when used without taking patient-, tumor- and treatment characteristics into account. This hurdle can be overcome by patient- individualized treatment approaches such as individualized dose-escalation using fixed dose constraints or adapting the treatment-fields to the shrinking tumor. However, adaptive radiotherapy (ART) is time consuming and it is not clear which patient is eligible or what the optimal time point for ART should be. Technical advances, such as intensity-modulated radiotherapy (IMRT) and tumor motion strategies, may further improve the therapeutic ratio. To reach full potential, these strategies imply the use of image-guided radiotherapy (IGRT), e.g. by using a cone-beam computed tomography (CBCT). The latter also allows monitoring tumor volume or -position changes over the treatment course. In this lecture we will address both anatomical- and especially tumor volume changes during chemoradiation and analyse potential predictive factors of volume and dosimetric parameter changes, as well as the potential gain to organs at risk (OARs) while maintaining target volume coverage. Furthermore, the optimal implementation strategy regarding selection of patients (who) and timing of imaging/replanning (when) will be discussed with an overview of the results, from a physician’s perspective. References: [1] Ferlay J et al. Estimates of worldwide burden of cancer in 2008 : GLOBOCAN 2008. Int J Cancer 2010 ;127: 2893 – 917. [2] Peters S et al. Metastatic non-small-cell lung cancer (NSCLC): ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up . Ann Oncol 2012 ; 23(Suppl 7) : vii56 – 64. [3] Auperin A et al. Meta-analysis of concomitant versus sequential radiochemotherapy in locally advanced nonsmall-cell lung cancer . J Clin Oncol 2010 ; 28 : 2181 – 90. [4] Bradley J. A review of radiation dose escalation trials for non-small cell lung cancer within the Radiation Therapy Oncology Group . Semin Oncol 2005 ; 32 : S111 – 3. SP-0409 Improvements in physics, DIBH in lung M. Josipovic 1 1 The Finsen Center - Rigshospitalet, Copenhagen, Denmark