Effect of Breast Volume on Treatment Reproducibility on a Tomotherapy Unit in the Treatment of Breast Cancer

Offerman, Shannon; Lamba, Michael; Lavigne, Rob

doi:10.1016/j.ijrobp.2010.02.022

Cited by 15 publications

(9 citation statements)

References 15 publications

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“…The absolute 3-dimensional distance of setup error was about 5 mm. In accord with our results, Offerman et al [ 19 ] in their evaluation of setup errors using helical TomoTherapy, suggested that the mean random shift for all patients in the lateral direction was 2.7 mm, longitudinal was 3.1, and vertical 3.2 mm. The mean absolute distance shifted was 6.0 mm.…”

Section: Discussionsupporting

confidence: 93%

Setup Error and Effectiveness of Weekly Image-Guided Radiation Therapy of TomoDirect for Early Breast Cancer

et al. 2015

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PurposeThis study investigated setup error and effectiveness of weekly image-guided radiotherapy (IGRT) of TomoDirect for early breast cancer.Materials and MethodsOne hundred and fifty-one breasts of 147 consecutive patients who underwent breast conserving surgery followed by whole breast irradiation using TomoDirect in 2012 and 2013 were evaluated. All patients received weekly IGRT. The weekly setup errors from simulation to each treatment in reference to chest wall and surgical clips were measured. Random, systemic, and 3-dimensional setup errors were assessed. Extensive setup error was defined as 5 mm above the margin in any directions.ResultsAll mean errors were within 3 mm of all directions. The mean angle of gantry shifts was 0.6°. The mean value of absolute 3-dimensional setup error was 4.67 mm. In multivariate analysis, breast size (odds ratio, 2.82; 95% confidence interval, 1.00 to 7.90) was a significant factor for extensive error. The largest significant deviation of setup error was observed in the first week of radiotherapy (p < 0.001) and the deviations gradually decreased with time. The deviation of setup error was 5.68 mm in the first week and within 5 mm after the second week.ConclusionIn this study, there was a significant association between breast size and significant setup error in breast cancer patients who received TomoDirect. The largest deviation occurred in the first week of treatment. Therefore, patients with large breasts should be closely observed on every fraction and fastidious attention is required in the first fraction of IGRT.

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Section: Discussionsupporting

confidence: 93%

Setup Error and Effectiveness of Weekly Image-Guided Radiation Therapy of TomoDirect for Early Breast Cancer

et al. 2015

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“…As for bony matching, patient setup error could be consistent regardless of their breast size as breast motion (soft tissue displacement and/or soft tissue deformation) is not taken into account. However, Offerman et al 32 found no correlation between breast size, BMI, height, weight and age and degree of daily shift on a tomotherapy unit for treatment of breast cancer. The main reason for the differing results could be due to the variation in patient position, flat in the Offerman study This study demonstrated correlation between BMI and breast size with setup errors measured with CBCT-S.…”

Section: Discussionmentioning

confidence: 99%

Comparison of setup accuracy of three different image assessment methods for tangential breast radiotherapy

et al. 2016

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IntroductionTo compare the differences in setup errors measured with electronic portal image (EPI) and cone‐beam computed tomography (CBCT) in patients undergoing tangential breast radiotherapy (RT). Relationship between setup errors, body mass index (BMI) and breast size was assessed.MethodsTwenty‐five patients undergoing postoperative RT to the breast were consented for this study. Weekly CBCT scans were acquired and retrospectively registered to the planning CT in three dimensions, first using bony anatomy for bony registration (CBCT‐B) and again using breast tissue outline for soft tissue registration (CBCT‐S). Digitally reconstructed radiographs (DRR) generated from CBCT to simulate EPI were compared to the planning DRR using bony anatomy in the V (parallel to the cranio‐caudal axis) and U (perpendicular to V) planes. The systematic (Σ) and random (σ) errors were calculated and correlated with BMI and breast size.ResultsThe systematic and random errors for EPI (Σ V = 3.7 mm, Σ U = 2.8 mm and σ V = 2.9 mm, σ U = 2.5) and CBCT‐B (Σ V = 3.5 mm, Σ U = 3.4 mm and σ V = 2.8 mm, σ U = 2.8) were of similar magnitude in the V and U planes. Similarly, the differences in setup errors for CBCT‐B and CBCT‐S in three dimensions were less than 1 mm. Only CBCT‐S setup error correlated with BMI and breast size.Conclusions CBCT and EPI show insignificant variation in their ability to detect setup error. These findings suggest no significant differences that would make one modality considered superior over the other and EPI should remain the standard of care for most patients. However, there is a correlation with breast size, BMI and setup error as detected by CBCT‐S, justifying the use of CBCT‐S for larger patients.

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“…In fact, all protocols required relatively small treatment margin expansions compared with the uncertainty introduced by tumor motion due to respiration, which is typically much larger in magnitude (AAPM Task Group 76 (31) reported 3.9–18.5 mm in SI direction for lung tumors) than residual systematic and random errors. Actually, Offerman et al (32) suggest that setup variation does not improve or degrade with repeated treatment setups for whole breast treatment, since no correlation between degree of daily shift and time course was found. For patients with boost or partial breast irradiation, Harris et al (33) showed that is possible to use the NI protocol when a PTV margin of 10 mm is applied, although high‐risk patients receiving simultaneous integrated boost with steep dose gradients may benefit from a margin reduction of 4 mm using a eNAL protocol, such as our AW protocol.…”

Section: Discussionmentioning

confidence: 99%

A retrospective tomotherapy image‐guidance study: analysis of more than 9,000 MVCT scans for ten different tumor sites

Sánchez-Rubio

Rodríguez-Romero

Castro

2014

J Applied Clin Med Phys

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The purpose of this study was to quantify the systematic and random errors for various disease sites when daily MVCT scans are acquired, and to analyze alternative off‐line verification protocols (OVP) with respect to the patient setup accuracy achieved. Alignment data from 389 patients (9,418 fractions) treated at ten different anatomic sites with daily image‐guidance (IG) on a helical tomotherapy unit were analyzed. Moreover, six OVP were retrospectively evaluated. For each OVP, the frequency of the residual setup errors and additional margins required were calculated for the treatment sessions without image guidance. The magnitude of the three‐dimensional vector displacement and its frequency were evaluated for all OVP. From daily IG, the main global systematic error was in the vertical direction (4.4–9.4 mm), and all rotations were negligible (less than 0.5°) for all anatomic sites. The lowest systematic and random errors were found for H&N and brain patients. All OVP were effective in reducing the mean systematic error to less than 1 mm and 0.2° in all directions and roll corrections for almost all treatment sites. The treatment margins needed to adapt the residual errors should be increased by 2–5 mm for brain and H&N, around 8 mm in the vertical direction for the other anatomic sites, and up to 19 mm in the longitudinal direction for abdomen patients. Almost 70% of the sessions presented a setup error of 3 mm for OVPs with an imaging frequency above 50%. Only for brain patients it would be feasible to apply an OVP because the residual setup error could be compensated for with a slight margin increase. However, daily imaging should be used for anatomic sites of difficult immobilization and/or large interfraction movement.PACS numbers: 87.55.‐x, 87.56.‐v

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Effect of Breast Volume on Treatment Reproducibility on a Tomotherapy Unit in the Treatment of Breast Cancer

Cited by 15 publications

References 15 publications

Setup Error and Effectiveness of Weekly Image-Guided Radiation Therapy of TomoDirect for Early Breast Cancer

Setup Error and Effectiveness of Weekly Image-Guided Radiation Therapy of TomoDirect for Early Breast Cancer

Comparison of setup accuracy of three different image assessment methods for tangential breast radiotherapy

A retrospective tomotherapy image‐guidance study: analysis of more than 9,000 MVCT scans for ten different tumor sites

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