Quality Improvement Investigation for Head and Neck Stabilization in Radiotherapy Using Setup Tattoos.

PURPOSE

Highly complex planning techniques and delivery methods in the treatment of head and neck cancer require an advanced level of accuracy and reproducibility.

AIM

To determine if the addition of tattoos placed on the chest inferior to the CIVCO Vac-Lok stabilization system improves accuracy and reproducibility of patient set up.

METHODS

Eighteen patients with head and neck cancer were studied. Nine underwent radical treatment using the routine CIVCO stabilization system. The second group of nine used the same stabilization device but were positioned daily with the use of tattoos. Daily orthogonal kilovoltage setup images were used to calculate setup errors. Displacements in the left/right (Lt/Rt), superior/inferior (Sup/Inf), and anterior/posterior (Ant/Post) directions were determined as well as pitch and yaw rotational errors.

RESULTS

Five hundred and twenty-three image pairs were analysed. Clinically significant differences were found in yaw error, Lt/Rt displacement, and Sup/Inf displacement in the tattooed patients. The median (interquartile range) absolute yaw error was larger for patients without tattoos: 1.4° (1.4° to 2.1°) compared to 0.8° (0.8° to 1.4°) for patients with tattoos. The percentage of both Sup/Inf and Lt/Rt errors >3 mm was also greater for patients without tattoos: 23.7% of Sup/Inf errors were >3 mm compared with 17.3% for patients with tattoos, and 22.3% of Lt/Rt errors were >3 mm compared with 10.0% for patients with tattoos.

CONCLUSION

The addition of chest tattoos resulted in clinically relevant improvements in Lt/Rt and Sup/Inf translational displacements and variations in yaw for head and neck cancer patients.