Effectiveness of the No action level protocol for head & neck patients – Time considerations

Abstract

Background

The No Action Protocol (NAL) was used to diminish the systematic set-up error. Recently, owing to the development of image registration technologies, the on-line positioning control is more often used. This method significantly reduces the CTV–PTV margin at the expense of the lengthening of a treatment session. The efficiency of NAL in decreasing the total treatment time for Head&Neck patients was investigated.

Methods

Results of set-up control of 30 patients were analyzed. The set-up control was carried out on-line. For each patient and each fraction, the set-error and the time needed for making the set-up control procedure were measured. Next, retrospectively, the NAL was applied to this data. The number of initial errors (without interventions) and after NAL protocol were compared in terms of errors larger than 3 and 4 mm. The average and total time used for portal control was calculated and compared.

Results

The number of setup errors in the posterior-anterior, inferior-superior, and right–left directions ≥3 mm and ≥4 mm were 98, 79, and 91 sessions and 44, 38 and 30 sessions out of 884 sessions. After NAL protocol the number of errors ≥3 mm and ≥4 mm decreased to 84, 57, and 39 sessions and 31, 15 and 10 sessions, respectively. The average time needed for one set-up control was 5.1 min. NAL protocol allows saving 4049 min for the whole group.

Conclusions

For locations where the random set-up errors are small, the NAL enables a very precise treatment of patients. Implementation of this protocol significantly decreases the total treatment time.