Suitable Frequency of Patient Position Check for Head and Neck Cancer Treated with Radiotherapy

Abstract

Radiotherapy is often used in head and neck cancer for complete cure through palliative care. The physical complex and purpose of treatment cannot focus only on complete cure, but must also consider the quality of life of patients during treatment and post-treatment. Image-guided radiation therapy (IGRT) has been used to improve the precision and accuracy of treatment, to reduce the exposure of healthy tissues during radiation treatments and thereby reduce complications from surrounding tissue damage. This qualitative research aimed to study the appropriate frequency of patient position check for head and neck cancer with radiotherapy, using an electronic portal imaging device (EPID). Radiographic verification was performed on 45 patients at 236 examination times, to check the positional accuracy of the anterior lower neck and the lateral face and neck in different directions. The radiotherapy image was checked once a week to compare different skull and spine positions (bony landmarks), and bodyweight was also recorded. Weight loss or gain during the treatment course was not consistent. The patient positioning errors at a variability of 0.5 cm or more occurred in 42 of 472 examinations (8.9%). The errors were found 20, 12, and 10 times in the first, second, and third verifications, accounting for 47.62%, 28.57%, and 23.81%, respectively. The largest offsets occurred in the left and right sides of the anterior lower neck field. It is suggested that image verification should be performed first in the anterior lower neck position in both the left and right sides to achieve the maximum benefit of controlling the essential dose and decreasing workload. The need for individual additional verification should be considered at the discretion of the doctor and physicist.