Saxsons Group

TruPose™ Head Adjuster — the bore-linac rotational-correction citable backbone.

TruPose closes the rotational-correction gap on bore-class linacs without a robotic couch. The evidence here has three layers: the peer-reviewed quantification of what the residual rotational errors look like in CBCT-aligned cranial SRS (Dhabaan 2012, Wilbert 2010), the dosimetric cost of leaving those rotations uncorrected (Liu 2015), and the AAPM TG-147 IGRT QA framework that makes rotational localisation a verified parameter.

5 % maximum PTV-coverage loss when 4DoF-only correction omits pitch/roll (Dhabaan 2012)
98.5 % fraction of treatment time within 0.4 mm / 0.2° when rotational correction is active (Liu 2015)
±4.0° TruPose per-axis range — four times the published worst-case residual yaw rotation
Product specs Physicist's notes
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Dhabaan 2012 — bore-class linac 6DoF correction residuals
Mean residual rotational error (any axis)
Max observed yaw residual
Max translational residual (longitudinal)
PTV-coverage loss with 4DoF only
Bore-class 6DoF residuals 2012
< 0.3° mean residual rotational error after 6DoF correction across 28 patients / 38 targets / 63 fractions. Max observed yaw rotation residual ~1°. With 4DoF correction alone (omitting pitch/roll), PTV-coverage loss reached 5 % depending on target geometry.

Six degrees of freedom CBCT-based positioning for intracranial targets treated with frameless stereotactic radiosurgery

Dhabaan A, Schreibmann E, Siddiqi A et al., J Appl Clin Med Phys 13(6):3850

Wilbert 2010 — phantom vs clinical 6DoF accuracy
0.2 mm / 0.7°
Phantom
translational ± rotational precision
vs
1.6 mm 3D
Clinical
7 patients, inter-fraction repositioning vector
First clinical 6DoF 2010
1.6 ± 0.8 mm clinical inter-fraction 3D vector repositioning across 7 patients; intra-fraction 3D rigidity 0.6 ± 0.4 mm. Phantom translational precision 0.2 ± 0.2 mm, rotational 0.7 ± 0.8°. Established the bore-class 6DoF performance envelope.

Semi-robotic 6 degree of freedom positioning for intracranial high precision radiotherapy; first phantom and clinical results

Wilbert J, Meyer J, Baier K et al., Radiat Oncol 5:42

Liu 2015 — time within tolerance, corrected vs uncorrected
With rotational correction (0.4 mm / 0.2°)
98.5 %
Without correction
10.7 %
Rotational tolerance vs dose 2015
98.5 % fraction of treatment time within 0.4 mm / 0.2° tolerance when motion correction is active (vs 10.7 % uncorrected, 7 volunteers, 20 corrected vs 5 uncorrected experiments). Authors note rotational deviation "significantly affects target dose coverage" for non-spherical or multi-site treatments.

Robotic real-time translational and rotational head motion correction during frameless stereotactic radiosurgery

Liu X, Belcher AH, Grelewicz Z, Wiersma RD, Med Phys 42(6):2755–2762

TG-147 — rotational-correction QA inputs
Translational localisation accuracy
Rotational localisation accuracy
End-to-end test required
Frequency
IGRT QA framework 2012
6DoF QA TG-147 sets the QA programme for non-radiographic localisation systems (including SGRT) and treats rotational localisation accuracy as a verified parameter — the SGRT delta is only as good as the QA that supports it.

AAPM TG-147 — Quality assurance for non-radiographic radiotherapy localization and positioning systems

Willoughby T, Lehmann J, Bencomo JA et al., Med Phys 39(4):1728–1747

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TruPose Head Adjuster — manufacturer product page

Manufacturer product overview and specification sheet.

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Manufacturer webinar recording on bore-class linac 6DoF SRS. Click the tile to play in-page.

TruPose™ Head Adjuster

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Closing the 3DoF rotational gap on bore-class linacs

Bore-class linacs (Halcyon, Ethos, Radixact) have 4DoF couches — translations plus a single rotation. SGRT reports the residual pitch/roll/yaw deltas. Without a robotic couch, how big does a 1° residual rotation actually look in the dose distribution for a 1.5 cm intracranial target, and where does TruPose plug into the workflow? Sourced to Dhabaan 2012 (4DoF vs 6DoF dose impact) + Liu 2015 (motion-correction tolerances).

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