Session Item

The aim of this study was to identify the impact of role delegation and responsibilities to RTTs on the time taken to treat various sites on an MR-Linac.

A service evaluation was carried out of all patients treated on a single MR-Linac between May 2019 and August 2022. The evaluation compared the time taken for each step in a patient’s treatment, using three workflows followed at our institution, with varying degrees of RTT responsibility within online adaptations. The levels are shown in Figure 1. These were A) clinician led (where the whole interdisciplinary team was present), B) clinician-lite (whereby image registration approval and acceptance of plan coverage on verification imaging was returned to the RTTs akin to a conventional linac), and C) RTT-led (where RTTs undertake tasks in step B alongside online plan adaptation). The time taken for each step in the workflow was recorded using a stopwatch, and the patients’ treatment approval documents were reviewed by a single observer to determine which delivery pathway was followed. Times taken for each process were compared to determine the impact of increased RTT responsibility in the online adaptations. Descriptive statistics were calculated.  Further analysis was performed using an unpaired two-sample assuming unequal variances t-test or ANOVA where appropriate. 

79 patients were treated during the study period (bladder = 1, head and neck = 3, lung = 4, prostate 20# = 33 and prostate 5# = 37) with a mean overall treatment time of 34:54 mins (range 22:35 to 78:43 mins). The total number of fractions analysed was 866 (Table 2).
For the three treatment sites with the largest patient numbers (lung, prostate and prostate SABR) the mean total plan time (indicated on figure 1 in the orange box) was significantly reduced from clinician led to both clinician-lite (p<0.001, p<0.001 and p=0.007) and RTT-led (p<0.001, p<0.001 and p=0.002). The overall treatment time reduction from clinician-led to clinician-lite and from clinician-lite to RTT-led was not significant.
For the two bladder patients treated, though the times appear to have reduced for the clinician-lite and RTT-led workflows, the results were not statistically significant for contouring, planning or overall treatment time, p=0.7, p=0.18, p=0.97 respectively.
For the three head and neck cases, all task times increased for both the clinician-lite and RTT-let workflows.  The increased time were only statistically significant for the overall treatment time (p=0.02), and not contouring (p=0.13) or planning (p=0.15) and p=0.02, respectively. This may be the result of lack of experience in these sites and may improve with more familiarity.

When treatments follow a ‘clinician-lite’ framework, the time taken to plan bladder, lung, prostate treatments were reduced, meaning a reduction in staff did not impact service capacity or patient experience. Lung and head and neck data will be revisited following more completed fractionations.