ESTRO 2020 Abstract Book

S3 ESTRO 2020

Abstract text Superficial skin cancer can be treated with a number of external beam modalities. The optimal technique is guided by depth of the target volume and proximity to organs at risk (OAR). The patient population is often elderly, and the ability to travel to the cancer center for repeat visits, as well as compliance with treatment setup and delivery must be taken into consideration when deciding on the dose fractionation regime and treatment modality. In this presentation, different methods for the treatment of superficial skin cancer with external beam radiation will be reviewed. Advantages and limitations of these methods will be discussed, along with comparison to brachytherapy techniques. Kilovoltage X-rays, including superficial and orthovoltage therapy, have the advantage of simple beam collimation, narrow penumbra, and relative ease of treatment setup; disadvantage includes the relatively slow dose drop off with higher energies and the high absorption of bone (f-factor) with lower energies. When using electron therapy the physical properties of the beam needs to be properly understood when prescribing treatment; bolus is required to ensure full surface dose, and an adequate margin around the target is needed to account for the wide penumbra, and as lower isodoses lines bow out at depth. The nuances of shielding are often more complicated with electron than with kilovoltage X- rays. Megavoltage photons are required for targets at depth, and IMRT or VMAT can be used to tailor the dose to cover large complex target volumes while minimizing dose to nearby OAR. IMRT and VMAT are useful techniques when treating large superficial targets over cured surfaces, such as the scalp. With stereotactic radiation, dose escalation to target is possible as using narrow margins, and may provide higher rates of tumor control and symptom palliation. However, rigid immobilization and longer treatment times are required and may not be well tolerated by all patients. Target delineation can be guided by incorporating ultrasound and MRI into the treatment planning process. Clinical cases will be used as examples, and recommendations given to help guide clinical practice. SP-0013 Which brachytherapy technique is optimal to manage complex skin targets? J. Guinot 1 , V. Gonzalez-Perez 2 1 Fundación Instituto Valenciano De Oncologia, Department Of Radiation Oncology, Valencia, Spain ; 2 fundación Instituto Valenciano De Oncologia, Department Of Radiation Physics, Valencia, Spain Abstract text Complex skin targets are related to extensive lesions as skull carcinomas with large targets, proximity of organs at risk as eye, anatomic uneven surfaces or cavities, and exophytic lesions. In all these situations, to achieve a good dosimetry is a challenge. New planning systems and high accuracy CLINACs allow for better isodose distributions, but air cavities and irregular shapes are difficult to be well covered. Dose on the skin is also a handicap, and bolus material not always adapts to the skin surface, Brachytherapy (BT) is being used for skin malignancies with excellent results. Most of the indications are related to small, not deep tumors or postoperative radiation to treat a few mm under the skin. These cases are well managed with contact brachytherapy, flaps, molds, or shielded devices. Complex skin targets need a different approach. Extensive superficial skull targets have dosimetric advantages when treated with personalized flaps or molds for contact brachytherapy. Dose is more homogeneous and brain receives lower doses. The proximity of organs at risk like eyes give advantage to interstitial BT due to the rapid fall-off of dose outside the target. Cavities like ear, orbit, nostrils, if included in the target offer the chance of making personalized molds to adapt the isodose to these irregular surfaces. And exophytic tumors need to be

future environment. The business dictionary defines a leader as a person or thing that holds a dominant or superior position within its field, and is able to exercise a high degree of control or influence over others (http://www.businessdictionary.com/definition/leader.h tml). The Collins dictionary defines a leader of a group of people or an organization is the person who is in control of it or in charge of it. Based on this narrow bsiness approach there are many RTT leaders in radiation oncology but do they actually demonstrate leadership or are they managing a service which, of course, is also valid? In a profession that, in the majority of countries, has no defined career pathway how can leaders rather than managers evolve? To support the evolution of leaders who are not necessarily managers but can come from any level within the team we need to take a broader view of the factors underpinning leadership. For the RTT profession to grow in the coming decades we must consider a leader as someone with a vision, who wants to bring about improvement and who guides and supports others to also become leaders. Professor Sandra Turner proposed that leadership in radiation oncology enables optimal clinical services and patient care, supports research and education and encourages initiatives at local, national and global level. Whilst there are many individual examples of leadership evolution amongst RTT community globally they are often in an individual silo with a predominantly local impact. The evolution of leadership from a pure management approach to one of vision and forward thinking impacting the totality of the profession is clearly demonstrated amongst the members of the ESTRO RTT community. Encompassing all elements of RTT practice and education members of this community are excellent examples of the evolution of leadership over three decades. Bringing their unique knowledge and skills they have supported the global growth of the profession from both a clinical and academic perspective. Dissemination of science through conferences, short courses, workshop and publications has grown exponentially over this period enabling colleagues to improve their own practice and thereby the care offered to patients. Coupled with the Train the Trainers project RTTs have been empowered to become directly involved in influencing the education standards within their local or national environment. The extensive network established has provided a platform for discussion and the evolution of shared vision for the future of the RTT profession and is a clear example of the evolution of leadership within our community. SP-0011 Simulation, applicator selection, planning and verification of complex skin targets. D. O'Farrell 1 1 Dana Farber/Brigham and Womens Cancer Center, Department of Radiation Oncology- Harvard Medical School, Boston, USA Abstract text Abstract: Surface brachytherapy necessitates some knowledge of specialized techniques and technologies to achieve safe and reproduceable treatment delivery. Here we show how our institution selects and treats patients with complex superficial targets and provide experience- based strategies for planning, optimization and verification. SP-0012 Which external beam modality is optimal? T. Barnes 1 1 Odette Cancer Centre, Radiation Oncology, Toronto, Canada Symposium: Management of complex skin targets-what is the optimal radiation technique?