ESTRO 2021 Abstract Book

S165

ESTRO 2021

activation, in particular the production of Ar-41 (T½ 110 minutes) can cause severe concerns in the application process but is insignificant in relation to radiation protection in a PT facility and, most important, extremely difficult to measure and quantify. But at the end of the day, do not let us forget why we want to use protons. PT gives a significantly lower exposure to non-target tissues and the significant reduction in integral dose, often far more than 50%, is frequently seen as an indication for PT, particularly for children and young adults. The need for accurate positioning and adaption is higher in proton RT but with the young profile of patients, it is of crucial importance not to dilute the reduction in integral dose by too extensive imaging.

SP-0250 Radiation protection when you are installing a PET-CT for planning: Tips and tricks TBC

SP-0251 Implementation of new BSS in a radiotherapy department: Implications for medical physicists B. McClean 1 1 St Luke’s Radiation Oncology Network, Physics, Dublin, Ireland Abstract Text Implementation of new BSS in a radiotherapy department: Implications for medical physicists The new BSS strengthens requirements in relation to the Justification principal, information on risks and benefits of ionising radiation and information on dose. It continues to identify the need for close involvement of the MPE in therapeutic procedures and sets out detailed responsibilities, education and training requirements for MPE’s in all areas of patient, staff and members of the public radiation exposure considerations. The listed responsibilities of the MPE have implications for medical physicists in radiotherapy in all areas of the patient pathway from imaging used in target volume definition to dose calculation and evaluation, treatment delivery and verification. There has been a dramatic increase in the use of ionising radiation for imaging in advanced radiotherapy treatment techniques in recent years, both in pre-treatment and image guided treatment delivery which allows better conformity of high dose to the target. The imaging dose is added to the high level of therapy dose and needs to be carefully managed through optimisation. It is important for the MPE to consider what the images are being used for and to understand the impact of the protocols on the selection of the appropriate image quality. The BSS makes it clear the MPE must be involved in the optimisation and evaluation of dose. In the treatment planning process this includes a determination of dose to non-target volumes and tissues. As a TPS is primarily designed for calculation of dose to target volumes, the effect of beam models and extensive use of small fields on determination of dose to non-target can be challenging. The ongoing success of radiotherapy in the primary treatment of disease leads to an increasing frequency of re-treatments as patients live longer. Re- treatment, together with the treatment of multiple metastatic disease further increases the requirement for accurate determination of non-target doses. The stated responsibility for the MPE to undertake appropriate physical measurement to evaluate dose to the patient continues to contribute to debate on the need for patient specific QA measurements. The use of hypofractionated treatments, flattening filter free beams and emerging FLASH beams require careful consideration of the measurement of dose. The BSS states the need for the MPE to take responsibility for appropriate quality assurance and risk assessment. In terms of delivery systems, the frequency, scope and analysis of quality control processes with modern advanced treatment techniques can be quite different from conventional QC approaches. The need for risk assessments is a recurring theme in the BSS. Balancing of the QC requirement with available resources and risk to the patient needs careful management. The use of incident reporting and investigation systems, including the availability of key databases such as SAFFRON and ROSEIS, can be used to assist in determining appropriate QC. The MPE needs to work closely with equipment manufacturers to understand their engineering controls and testing along with the effect of failure before installation of the systems. Further systems to prevent accidents or minimise the severity and duration can then be developed. The BSS also requires member states to establish criteria of acceptability for equipment, including when to take equipment out of clinical use. This in turn requires the MPE to undertake a detailed uncertainty analysis of the equipment and techniques and use this knowledge to establish QC and acceptable performance of equipment consistent with the intended therapeutic use. Extensive education and training of MPE’s is a clear consequence of the responsibilities set out in the BSS. The EFOMP pathway to becoming an MPE sets out the education and qualification framework to ensure MPE’s are suitably qualified to meet the requirements of the BSS. The core curriculum for MPE has been recently reviewed to accommodate changing technology and increases in the use of artificial intelligence in healthcare settings. While many opportunities for ongoing CPD for MPE’s are available through for example ESTRO and EFOMP education programmes, time for staff to undertake such training is a logistical challenge for departments. The determination of an appropriate number of MPE in a department to undertake the clinical service and meet the needs of CPD and the range of BSS responsibilities is at times controversial and leads to ongoing discussion in the professional bodies.

SP-0252 Justification and optimisation of radiation doses for imaging in radiotherapy A. Torresin 1 1 ASST GOM Niguarda and Physics University, Medical Physics Dep., Milano, Italy

Abstract Text The use of imaging in radiotherapy for planning and verification purpose has constantly increased in the last decade. The benefits offered are evident, an improved imaging for dosimetric planning, patient positioning prior to treatment, replanning related to the new dosimetric evaluation, but it is always important to remember and