Improving the reproducibility of lateral therapy portal placement

Quality improvement process to assess tattoo alignment, set‐up accuracy and isocentre reproducibility in pelvic radiotherapy patients

“…1). 14 Greer et al focussed his study on isocentre depth accuracy but also noted that lateral tattoos were aligned to each other and defined CC isocentre position 15,16. A correlation between the measured distance of the AP and lateral tattoos in the CC plane and the averaged CC isocentre position on paired AP and lateral EPIs of the same treatment fraction in cohort 2 patients supported Williamson's proposal.…”

“…For cohort 3 patients, lateral tattoos were aligned to minimise roll and yaw and pitch was also minimised by ensuring the anterior tattoo was within 5 mm of lateral tattoos in the CC direction. A 5 mm tolerance was considered acceptable as difficulty is often experienced with aligning the anterior tattoo to the lateral tattoos due to anterior tattoo movement vulnerability as previously discussed 6,14. Cohort 3 results achieved the most noteworthy improvements in set-up accuracy.…”

“…However, cohort 2 CC set-up errors did not decrease nor did isocentre reproducibility increase upon cohort 1 (Tables 1 and 2). This strongly suggested that the major contributor to this error was setting CC isocentre position relative to the anterior tattoo which is subject to movement due to weight changes and daily bladder volume variations 6,13,14. Williamson hypothesised that aligning the lateral tattoos to each other and using these to set CC isocentre position would be more accurate as the “lateral tattoos represented two points in line with the approximate position of the isocentre and as such were less subject to movement than the anterior skin surface” (Fig.…”

Human factors evaluation of teletherapy: Literature review. Volume 5

“…According to Hendrickson (1982), "the problem of possible patient movement during the course of treatment and the ability to reproduce the patient position on subsequent treatments may be one of the major problems in radiation oncology" (p. 31 1). The importance of this routine but difficult-to-replicate aspect of treatment has been noted by other authors as well (Barish & Lerch, 1978;Bentel et al 1989;Kartha, Chung-Bin, Wachtor & Hendrickson, 1975;Goldson, Young, Espinoza & Henschke, 1978;Huaskins & Thomson, 1973;Verhey, Goitein, McNulty, Munzenrider &Suit, 1982, andWilliamson, 1979). Alignment lasers are used to enhance the reproducibility of the patient's position; a number of positioning and immobilization devices -body casts, Alpha Cradle, Aquaplast, Scotchcast, arm boards, head and neck cradles, bite blocks -have become an integral part of patient set-up that is reflected in treatment planning.…”

“…The next area of uncertainty that also has received considerable notice in the literature is patient positioning and immobilization (e.g., Barish & Lerch, 1978;Bentel et al 1989;Hendrickson, 1982;Kartha, Chung-Bin, Wachtor & Hendrickson, 1975;Goldson, Young, Espinoza & Henschke, 1978;Huaskins & Thomson, 1973;Rabinowitz, Broomberg, Goitein, McCarthy & Leong, 1985;Svensson, 1989;Verhey, Goitein, McNulty, Munzenrider &Suit, 1982, andWilliamson, 1979). Whatever the patient's treatment position, it can not be so awkward and uncomfortable that it precludes reproducibility or encourages movement.…”