ESTRO 2023 - Abstract Book

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ESTRO 2023

Among forty patients, twenty patients (50%) developed clinical signs and symptoms of musculopathy. Among these patients, the most common symptom was pain (60%) and stiffness (60%). Other toxicities included rigidity (40%) and difficulty in neck movements (20%). The highest mean doses were received by SCM and scalene muscles receiving 70Gy & 68Gy respectively. V30 of trapezius, SCM, scalene, capitus & levator scapulae were 31%, 91%, 93%, 56% & 73%. Function of the muscles when compared to pre and post CTRT were as follows- shrugging of shoulder (50%); head tilt test and rotation of head (40%) each and the p values were significant (p< 0.05); flexion and extension of head – (10%) and overhead abduction was not seen in any of the patients. The most common grade of weakness of the neck muscles were grade I followed by grade II & none of the patients developed grade III weakness. The median latency period of developing these symptoms was 2.5 to 3 months.

Conclusion Radiation induced myopathy in neck muscles is one of the late complications in head and neck cancers, which is not clinically assessed or detected. Therefore, neck muscles must be considered as an OAR in the contouring of head and neck cancers. Further studies with longer follow up are needed.

PO-1224 A framework to link 3D radiotherapy to 2D ophthalmological findings

M.K. Hassan 1 , B. Kinaci-Tas 1,2 , F. Dankers 1 , B. Stoel 3 , L. Stalpers 4 , F. Verbraak 5 , C. Rasch 1 , T. Alderliesten 1

1 Leiden University Medical Center, Radiation Oncology, Leiden, The Netherlands; 2 Amsterdam University Medical Centers, Ophthalmology, Amsterdam, The Netherlands; 3 Leiden University Medical Center, Radiology, Leiden, The Netherlands; 4 Amsterdam University Medical Center, Radiation Oncology, Amsterdam, The Netherlands; 5 Amsterdam University Medical Center, Ophthalmology, Amsterdam, The Netherlands Purpose or Objective Radiation-induced retinopathy (RR) is a potential side effect of radiation treatment for head and neck tumors because of partial eye irradiation. 2D ultra-wide-field fluorescein angiography (UWFA) is a standard ophthalmological test to measure RR. The severity of RR is likely to be correlated with the radiation dose to the retinal surface. To enable investigation of the relationship between the 3D dose distribution and RR, we developed a framework that can link the 3D dose distribution to UWFA-based RR findings. Further, we assessed the impact of variability in ocular contour delineation (OCD) on the robustness of the extracted dosimetric values from the 3D dose distribution, and their applicability in a potential future dose-response model.