Impact of body-mass factors on setup displacement in patients with head and neck cancer treated with radiotherapy using daily on-line image guidance

Abstract

BackgroundTo determine the impact of body-mass factors (BMF) before radiotherapy and changes during radiotherapy on the magnitude of setup displacement in patients with head and neck cancer (HNC).MethodsThe clinical data of 30 patients with HNC was analyzed using the alignment data from daily on-line on-board imaging from image-guided radiotherapy. BMFs included body weight, body height, and the circumference and bilateral thickness of the neck. Changes in the BMFs during treatment were retrieved from cone beam computed tomography at the 10th and 20th fractions. Setup errors for each patient were assessed by systematic error (SE) and random error (RE) through the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions, and couch rotation (CR). Using the median values of the BMFs as a cutoff, the impact of the factors on the magnitude of displacement was assessed by the Mann–Whitney U test.ResultsA higher body weight before radiotherapy correlated with a greater AP-SE (p = 0.045), SI-RE (p = 0.023), and CR-SE (p = 0.033). A longer body height was associated with a greater SI-RE (p = 0.002). A performance status score of 1 or 2 was related to a greater AP-SE (p = 0.043), AP-RE (p = 0.015), and SI-RE (p = 0.043). Among the ratios of the BMFs during radiotherapy, the values at the level of mastoid tip at the 20th fraction were associated with greater setup errors.ConclusionsTo reduce setup errors in patients with HNC receiving RT, the use of on-line image-guided radiotherapy is recommended for patients with a large body weight or height, and a performance status score of 1–2. In addition, adaptive planning should be considered for those who have a large reduction ratio in the circumference (<1) and thickness (<0.94) over the level of the mastoid tip during the 20th fraction of treatment.

Adaptive radiotherapy for head and neck cancer

“…The median follow-up ranged from 29 to 38 months. Tumors were located primarily in the oropharynx [16,18,38] or the nasopharynx [17,19]. The dose delivered to the high-risk volume ranged from 66 to 76 Gy.…”

“…The time point ranged from the second fraction to the 28th fraction for the first replanning session and from the 11th fraction to the 25th fraction for the second replanning session. Three studies reported the clinical results of ART in comparison with a no-ART technique [17,19,38] without randomization. Two studies were prospective [16,19], while the remaining three studies were retrospective [17,18,20].…”

Optimal adaptive IMRT strategy to spare the parotid glands in oropharyngeal cancer

“…Large anatomical variations can, however, occur during the treatment, such as weight loss [4,5], primary tumor shrinking [4], parotid gland (PG) volume reduction [6], and neck diameter reduction [7][8][9]. These modifications may generate differences between the planned and actual delivered doses, inducing the risk of PG radiation overdose [10,11] that can potentially increase the risk of xerostomia [12].…”

The ratio of weight loss to planning target volume significantly impacts setup errors in nasopharyngeal cancer patients undergoing helical tomotherapy with daily megavoltage computed tomography

“…Furthermore, weight loss greatly impacts setup error magnitude, and is consistent with previous findings in patients treated with head and neck RT. 13, 20, 21 Weight loss during RT for head and neck cancers is multi-factorial. Ionizing radiation, along with concurrent systemic chemo-therapy, induces acute mucositis and taste change.…”