Observation of the effect of organ displacement on target area of intensity-modulated radiotherapy during swallowing for head and neck cancer based on dynamic MRI images / 中华放射肿瘤学杂志

ABSTRACT

Objective:Continuous acquisition of swallowing images of head and neck cancer patients by using MRI technique was performed to observe and measure the movement regularity and maximum displacement of the soft palate, tongue and larynx.Methods:From July 2018 to October 2018, 20 patients with primary head and neck cancer were chosen randomly, 17 male and 3 female. The median age was 58.5 years (28 to 78 years). Among the 20 patients, 7 patients were diagnosed with nasopharyngeal carcinoma, 3 patients with oral cancer, 5 patients with oropharyngeal cancer, 3 patients with hypopharyngeal cancer, and 2 patients with nasal and paranasal sinuses cancer. Two patients were classified as stage Ⅰ-Ⅱ, 8 patients as stage Ⅲ and 10 patients as stage Ⅳ according to the eighth edition of AJCC.Results:The displacement of the upward movement of the soft palate during swallowing was (1.06±0.31) cm and followed the pattern normal distribution. The displacement of backward movement of the soft palate was (0.83±0.24) cm, which also almost normally distributed. The displacement of backward tongue movement was (0.77±0.22) cm and followed the normal distribution pattern. The displacement of upward tongue movement was 0 in patients with tongue depressor for image acquisition. The mediandisplacement of upward tongue movement in patients without tongue depressor was 1.23 cm (0.59 to 1.41 cm). The displacement of upward laryngeal movement was (1.14±0.22) cm and followed the normal distribution pattern, and the median displacement of forward laryngeal movement was 0.4 cm (0.27 to 0.90 cm).Conclusions:Swallowing movement may occur in head and neck cancer patients during radiotherapy. It can also cause the movement of gross tumor volume (GTV) and surrounding normal tissues. Therefore, extensive attention should be paid to the individual distance between GTV and planning gross tumor volume (PGTV) when making radiotherapy plans, aiming to ensure the prescription dose of cancer.