ESTRO 2021 Abstract Book

S371

ESTRO 2021

evaluated which led to a change from the conventional 4D Thorax to 4D Abdo protocol which gave almost diagnostic cardiac quality images to define the target. Throughout this development period we worked closely with our colleagues in 2 other centres in the North of England who were implementing this technique at the same time. This allowed us to exchange ideas and get the best from the technology we were using. For all new SABR sites that we implement we have a multidisciplinary team present at treatment delivery. In this case the multidisciplinary team present was much larger as it included Cardiologists and radiologists. It was imperative that the radiographers provided the appropriate leadership of this group at the point of delivery to ensure the best possible outcome for the patient. This is particularly important as the ICD is switched off for treatment delivery and the patient needs to be carefully monitored throughout to ensure that they don’t go into VT at any point. SP-0482 SGRT - A hype or the new standard of practice? S. Perryck 1 , M. Guckenberger 2 1 University Hospital Zurich, Department of Radiation Oncology, Zurich, Switzerland; 2 University Hospital of Zurich, Department of Radiation Oncology, Zurich, Switzerland Abstract Text The first regulatory approval of a Surface Guided Radiation Therapy (SGRT) system was in 2006, other commercial SGRT systems have followed in the last 10 years. Can we still call SGRT a hype or has it become a new component standard of radiotherapy practice? The SGRT systems that are available can be seen as the computerized version of radiation oncology professionals setting up a patient by skin marks with the lasers in the treatment room. Looking at SGRT from this perspective, it could be perceived as a natural step forward in the digital age. Will it therefore reduce or even eliminate human errors in the set-up process? Or is SGRT a threat and a replacement for the skillset of patient positioning, that has been exclusively done by radiation therapists and nurses. With SGRT a more accurate patient set up is possible, resulting in fewer imaging which reduces treatment time. Changes in surface are detected early and therefor an adaptation of the treatment plan will ensure a continuously good treatment. SGRT helps reducing incidents for example setting up the wrong patient. Monitoring the patient during treatment reduces the risk of mistreatment due to intra-fraction motion. By proving these benefits, SGRT will be the new standard of practice. Maybe the commercially available systems that are on the market have already reached their full potential. Some are fully integrated in the linac, others are standalone systems, both can control beam delivery. Either way, the systems provide information about the position of the patients. New soft- and hardware can potentially provide this information faster but is that an improvement or a way for companies to exploit an existing system. Have we therefore seen the best of this technique and will it be forgotten in 10 years? Radiation oncology is field in which many new developments are focused on improving the accuracy of treatment delivery. SGRT can be an asset in monitoring patient movement during treatment, without giving extra dose. The question remains, how much you can and should rely on a SGRT System. As with every other new technique, you must be aware of the system downfalls and have a backup plan ready. All radiation oncology professionals need to be trained to use the system. The system also needs to be maintained and quality assurance checks needs to be performed regularly. If SGRT is a hype this system will find its way to the storage closet, joining a couple of old or non-functional accessories catching dust. If SGRT is the new standard of practice, we need to think about standardizing the usage, guidelines, and education for the next group of radiation oncology professionals. Abstract Text Over the last 30 years, major advances have been made in the treatment of lymphomas, here Hodgkin’s lymphoma. In 2018 we saw approximately 80000 new cases worldwide, accounting for 0.4% of all new tumours [1]. In Sweden with a 10 million population, approximately 200 new cases are seen yearly. Even though chemotherapy is very effective in Hodgkin’s lymphoma, radiotherapy plays a very important role of the treatment. And as radiotherapy have evolved, so has the treatment of Hodgkin’s lymphoma. 30 years ago, large mantle fields or inverted Y were the standard and treated all lymphatic nodes cranial or caudal of the diaphragm. Today, with the aid of better imaging, affected nodes can be pinpointed, the resulting target volume kept smaller, and with advanced radiotherapy techniques, irradiated volumes can be kept smaller as well. Can we enhance the radiotherapy we deliver today? Depending on stage, radiotherapy (RT) today will consist of treatment to involved node (INRT) or involved site (ISRT). Doses usually lies between 20-30 Gy, more seldom 40 Gy. The volume is smaller today, but we still see some quite large target volumes, as the RT will involve the initially engaged nodes. The organs at risk (OAR) to consider are heart, lungs, thyroid, parotid glands, esophagus, and mammary glands and if the target is within the lower pelvis, kidneys, uterus, and the ovaries will have to be considered. Today many patients are treated with different breath-hold techniques. The advantages with breath-hold, would be both to have the target movement under control and adding to the distance between the target and the OARs [2]. With rotational therapy the doses to OARs can be kept lower compared to 3D conformal therapy (3DCRT). However, the rotational techniques add dose to the whole circumference of the patient, and all possible OARs must be delineated to be considered in the optimization. The possible advantages with protons could be lower doses to organs at risk. But to consider protons it is important to evaluate the patient breathing pattern, how much the target moves, and if possible, use a breath-hold technique. The protons physical properties are what we want to use to lessen the dose to OARs. However, it may interfere with the breathing motion and add to the uncertainty using protons. This means that unless breathing motion is very SP-0483 Innovative practice for lymphoma radiotherapy - Can we use protons for this? I. Kristensen 1 , M. Enmark 1 , A. Edvardsson 1 1 Skane University Hospital, Radiation Physics, Lund, Sweden