IntroductionThis quality improvement study tested three methods of tattoo alignment and isocentre definition to investigate if aligning lateral tattoos to minimise pitch, roll and yaw decreased set-up error, and if defining the isocentre using the lateral tattoos for cranio-caudal (CC) position improved isocentre reproducibility. The study population was patients receiving curative external beam radiotherapy (EBRT) for prostate cancer. The results are applicable to all supine pelvic EBRT patients.MethodsThe three sequential cohorts recruited 11, 11 and 10 patients respectively. A data set of 20 orthogonal pairs of electronic portal images (EPI) was acquired for each patient. EPIs were matched offline to digitally reconstructed radiographs. In cohort 1, lateral tattoos were adjusted to minimise roll. The anterior tattoo was used to define the isocentre. In cohort 2, lateral tattoos were aligned to minimise roll and yaw. Isocentre was defined as per cohort 1. In cohort 3, lateral tattoos were aligned as per cohort 2 and the anterior tattoo was adjusted to minimise pitch. Isocentre was defined by the lateral tattoos for CC position and the anterior tattoo for the left–right position.ResultsCohort 3 results were superior as CC systematic and random set-up errors reduced from −1.3 mm to −0.5 mm, and 3.1 mm to 1.4 mm respectively, from cohort 1 to cohort 3. Isocentre reproducibility also improved from 86.7% to 92.1% of treatment isocentres within 5 mm of the planned isocentre.ConclusionThe methods of tattoo alignment and isocentre definition in cohort 3 reduced set-up errors and improved isocentre reproducibility.

We compared cardiometabolic demand and post-exercise enjoyment between continuous walking (CW) and time-and intensity-matched interval walking (IW) in insufficiently active adults. Sixteen individuals (13 females and three males, age 25.3 ± 11.1 years) completed one CW and one IW session lasting 30 min in a randomised counterbalanced design. For CW, participants walked at a mean intensity of 65-70% predicted maximum heart rate (HR max ) . For 36 IW, participants alternated between 3 min at 80% HR max and 2 min at 50% HR max . Expired gas 37 was measured throughout each protocol. Participants rated post-exercise enjoyment 38 following each protocol. Mean HR and V� O 2 showed small positive differences in IW vs. CW (2, 95%CL 0, 4 beat.min -1 ; d = 0.23, 95%CL 0.06, 0.41 and 1.4, 95%CL 1.2 ml.kg -1 .min -1 , d = 0.36, 95%CL 0.05, 0.65, respectively). There was a medium positive difference in overall kcal expenditure in IW vs. CW (25, 95%CL 7 kcal, d = 0.58, 95%CL 0.33, 0.82). Post-exercise enjoyment was moderately greater following IW vs. CW (9.1, 95%CL 1.4, 16.8 AU, d = 0.62, 95%CL 0.06, 0.90), with 75% of participants reporting IW as more enjoyable. Interval walking elicits meaningfully greater energy expenditure and is more enjoyable than CW in insufficiently active, healthy adults.