Per-site build sheet · Patient Positioning Solutions
The baseplate platform covers H&N IMRT, brain SRS, breast DIBH, pelvic IMRT, lung SBRT and MR-linac transfer. This page is the per-site build sheet — baseplate + headrest + accessory mix — plus the AAPM TG-142 / TG-101 setup-reproducibility tolerance each workflow targets.
Baseplate
Head / neck / shoulder
Headrest
Silverman or C-profile
Extras
Thermoplastic mask + shoulder-retraction strap
Reproducibility target
< 3 mm translation, < 2° rotation inter-fraction (AAPM TG-142)
Notes: Shoulder retraction is the dominant axis — drops the shoulders out of the cervical / supraclavicular treatment field; without it the field needs to wrap around the shoulder muscle bulk and the dose-fall-off geometry suffers.
Baseplate
Head-only baseplate
Headrest
C-profile or paediatric variant
Extras
Frameless thermoplastic mask + intra-fraction SGRT verification
Reproducibility target
< 1 mm translation, < 1° rotation per fraction (SRS dose-fall-off requirement)
Notes: Indexed locking-hole array matches the CT-sim and the linac at < 1 mm reproducibility; intra-fraction SGRT verification picks up any drift during the single SRS fraction.
Baseplate
Thorax baseplate
Headrest
Standard A or B-profile
Extras
Variable-angle breast board + above-head T-bar grip + SGRT chest-rise signal
Reproducibility target
< 5 mm setup at chest wall; DIBH breath-hold gate at ±3 mm gating window
Notes: Breast board angle indexed for reproducibility across the fraction series; T-bar grip ergonomics maintained for DIBH workflows where the patient holds breath for 15–25 s per arc.
Baseplate
Pelvis baseplate
Headrest
Standard A-profile (head position not critical)
Extras
Knee-foot support + prone board (where prone workflow is preferred)
Reproducibility target
< 5 mm prostate setup with daily CBCT IGRT; knee-foot reproducibility within < 2° femoral rotation
Notes: The knee-foot is the dominant axis — without it the upper-body shell can be perfectly indexed but the patient still rolls by 5–7 mm at the prostate. Prone variant displaces small bowel for rectum work, dropping small-bowel dose by ≈ 10–15 % vs supine.
Baseplate
Thorax baseplate
Headrest
Standard A-profile
Extras
Vacuum cushion + arm-support T-bar + 4D-CT or breath-hold gating
Reproducibility target
ITV-based ITV margin per AAPM TG-101 (typically 5 mm CTV-to-PTV after motion management)
Notes: The baseplate-to-cushion indexing chain is the SBRT reproducibility backbone. Vacuum cushion conforms within fraction; baseplate locks fraction-to-fraction. Both layers are required by AAPM TG-101.
Baseplate
MR-compatible variant matching the linac-side baseplate
Headrest
MR-safe variant from the same library
Extras
MR-safe indexing pins + MR-compatible vacuum cushion (if SBRT workflow)
Reproducibility target
Setup transfers from MR-sim to MR-linac at the same indexed-pitch reproducibility as CT-sim to conventional linac
Notes: Non-ferromagnetic composite construction means no B0-field perturbation and no MR-image artefact. Same indexed locking-hole array as the conventional baseplate — the planning isocentre transfers without per-room recalibration.
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