Analysis of Daily Setup Variation With Tomotherapy Megavoltage Computed Tomography

Zhou, Jining; Uhl, Barry M.; Dewit, Kelly; Young, Mark; Taylor, Brian; Fei, Ding-Yu; Lo, Yeh-Chi

doi:10.1016/j.meddos.2009.01.005

Cited by 27 publications

(25 citation statements)

References 36 publications

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“…9) In our study, Y and Z directions were higher than at X. Moreover, the maximum displacements at X, Y, Z, and Roll were 3.9 mm, -7.9 mm, 6.7 mm, and 1.5°, respectively.…”

Section: Resultssupporting

confidence: 43%

“…Table 1 to account for variations in size, shape, and the CTV. 9,15) The setup margin formulas used the systematic and random errors.…”

Section: Resultsmentioning

confidence: 99%

“…However, correction of the axis of X (pitch) and Z (yaw) angles are impossible due to couch limitations with similar properties like CT platform. [7][8][9] The patient setup variations by occurred the translational and rotational displacement can cause the geometric uncertainty during the treatment. Kaiseret et al 8) has analyzed the rotational errors for patients with the head and neck cancer, and reported that the rotational setup errors have effect depend on the couch hardware design in Tomotherapy.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rotation Errors of Breast Cancer on 3D-CRT in TomoDirect

et al. 2015

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“…9) In our study, Y and Z directions were higher than at X. Moreover, the maximum displacements at X, Y, Z, and Roll were 3.9 mm, -7.9 mm, 6.7 mm, and 1.5°, respectively.…”

Section: Resultssupporting

confidence: 43%

“…Table 1 to account for variations in size, shape, and the CTV. 9,15) The setup margin formulas used the systematic and random errors.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rotation Errors of Breast Cancer on 3D-CRT in TomoDirect

et al. 2015

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“…Although other authors 20 , 21 have made similar analyses, this study also investigates alternative OVPs in relation to the patient setup accuracy achieved. An adequate OVP would allow an improved utilization of the unit at the same time that dose escalation and OAR sparing through a reduction in the PTV remain possible in as safe way as daily IG.…”

Section: Discussionmentioning

confidence: 96%

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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“…the daily variations of the mean tumor position stemming mostly from diaphragm driven processes [9], must be taken into account with safety margins. In that regard, the mid-position (MidP) strategy [10] allows a significant reduction of the tumor motion contribution in the planning target volume (PTV) margin computation, while MV-CT scans efficiently decrease the residual patient setup errors [11].…”

Section: Introductionmentioning

confidence: 99%