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

Elsner K, Francis K, Hruby G, Roderick S - J Med Radiat Sci (2014)

Bottom Line: The results are applicable to all supine pelvic EBRT patients.Cohort 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.

View Article: PubMed Central - PubMed

Affiliation: Sydney Cancer Centre, Department of Radiation Oncology, Royal Prince Alfred Hospital Sydney, Australia.

ABSTRACT

Introduction: This 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.

Methods: The 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.

Results: Cohort 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.

Conclusion: The methods of tattoo alignment and isocentre definition in cohort 3 reduced set-up errors and improved isocentre reproducibility.

No MeSH data available.


Related in: MedlinePlus

Illustrates pitch, yaw and roll as rotation about three axes.
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fig02: Illustrates pitch, yaw and roll as rotation about three axes.

Mentions: Globally, many centres practicing daily image-guided radiotherapy (IGRT) are limited to correcting translational errors via couch movement in three dimensions only. This inability to correct pitch, yaw and roll (Fig. 2) via couch movement means accurate in-room patient tattoo alignment and isocentre definition remains valid and valuable in the IGRT era.10 Treatment units with six degrees of freedom are commercially available but access to all patients in still limited. Furthermore, tattoo alignment continues to play an important role in identifying correct treatment sites, in patient groups without fiducial markers, in cases where daily IGRT is not appropriate or necessary, and where daily IGRT is not available such as radiotherapy centres in developing nations.11,12


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

Elsner K, Francis K, Hruby G, Roderick S - J Med Radiat Sci (2014)

Illustrates pitch, yaw and roll as rotation about three axes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4282035&req=5

fig02: Illustrates pitch, yaw and roll as rotation about three axes.
Mentions: Globally, many centres practicing daily image-guided radiotherapy (IGRT) are limited to correcting translational errors via couch movement in three dimensions only. This inability to correct pitch, yaw and roll (Fig. 2) via couch movement means accurate in-room patient tattoo alignment and isocentre definition remains valid and valuable in the IGRT era.10 Treatment units with six degrees of freedom are commercially available but access to all patients in still limited. Furthermore, tattoo alignment continues to play an important role in identifying correct treatment sites, in patient groups without fiducial markers, in cases where daily IGRT is not appropriate or necessary, and where daily IGRT is not available such as radiotherapy centres in developing nations.11,12

Bottom Line: The results are applicable to all supine pelvic EBRT patients.Cohort 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.

View Article: PubMed Central - PubMed

Affiliation: Sydney Cancer Centre, Department of Radiation Oncology, Royal Prince Alfred Hospital Sydney, Australia.

ABSTRACT

Introduction: This 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.

Methods: The 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.

Results: Cohort 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.

Conclusion: The methods of tattoo alignment and isocentre definition in cohort 3 reduced set-up errors and improved isocentre reproducibility.

No MeSH data available.


Related in: MedlinePlus