Knowledge Hub · Saxsons Fixed Laser Positioning
AAPM TG-142 expects ≤ 2 mm patient-positioning-laser-to-isocentre alignment for routine treatments and ≤ 1 mm for stereotactic-class work. The Saxsons own-brand fixed laser system delivers < 0.5 mm ISO-centre adjustment precision by default — a factor of two tighter than the stereotactic threshold. Semiconductor red 635 nm Class II lasers, two cross + one linear configuration, < 1 mm line width at 3–5 m. This page unpacks why.
Why this matters
< 0.5 mm ISO-centre precision
AAPM Task Group 142 frames the daily / monthly / annual QA expectations for a linac. The patient-positioning-laser-to-radiation-isocentre alignment is a daily-QA check: the published tolerance is ≤ 2 mm, with ≤ 1 mm as the stereotactic-class action threshold. The Saxsons fixed laser system is engineered for < 0.5 mm ISO-centre adjustment precision — a factor of two tighter than the stereotactic threshold. Every treatment in the room can run at stereotactic precision without a separate alignment cycle.
Based on: AAPM TG-142 — Quality Assurance of Medical Accelerators.
Read source ↗Semiconductor red 635 nm
Semiconductor laser diode designs replace the older gas-laser tube architecture. Three practical consequences: the device runs Class II eye-safe at the IEC 60825-1 classification used in clinical lighting; the diode does not drift with ambient temperature the way a tube does; and the failure mode of "tube end-of-life replacement every 2 years" disappears. The line stays straight, narrow and stable across the lifetime of the diode.
Based on: IEC 60825-1 Laser Safety Classification; manufacturer optical-design rationale.
Read source ↗2 cross + 1 linear configuration
A complete patient-positioning system needs three independent alignment axes converging at iso-centre. The Saxsons fixed configuration delivers two cross lasers (orthogonal cross-hairs on the patient lateral sides) and one linear laser (single line along the patient sagittal midline). Daily QA reads each axis independently — a drift in one axis without the others is the first signal that a specific mount has shifted, not that the whole iso-centre is off.
Based on: AAPM TG-179 — CT-simulator and treatment-vault patient positioning systems.
Read source ↗< 1 mm line width at 3–5 m
A narrow line width at the patient surface lets the radiation therapist read the alignment to within a millimetre by eye. Older laser designs project lines that widen with distance to several millimetres at the patient — soft, washed-out lines that hide alignment error. The Saxsons design maintains < 1 mm line width at the typical 3–5 m projection distance from wall mount to patient surface. Read the line precisely; align the patient precisely.
Based on: Manufacturer optical specification; AAPM TG-142 patient-positioning laser line-width expectations.
Read source ↗Linac · cobalt · simulator · CT-sim
Indian radiotherapy departments operate a mix of room types — modern linacs, older cobalt units in continued operation, dedicated CT-simulators and conventional X-ray simulators. The Saxsons fixed laser system serves all four from a single product line. The hospital procures one model across multiple rooms; the service contract covers all installed units; the QA protocol is consistent across the facility.
Based on: Saxsons product framing; AERB radiotherapy-facility licensing covering accelerator + cobalt + simulator + CT.
Read source ↗Saxsons local service
The same Saxsons team that supplies the laser system installs it, commissions it against the linac isocentre, supplies the acceptance-test documentation, and returns annually to verify the alignment hasn't drifted out of the < 0.5 mm precision. No overseas teleassistance dependency; no third-party service contractor in the loop. One supplier across procurement and lifecycle.
Based on: Saxsons service framing; consistent with Saxsons own-brand Dose Cabinet lifecycle approach.
Read source ↗AAPM, IEC and AERB documents that frame radiotherapy patient-positioning laser systems.
AAPM framework for daily / monthly / annual linac QA including patient-positioning laser tolerance specifications.
AAPM task-group framing for patient-positioning systems across imaging and treatment.
International standard for laser product safety classification, including the Class II designation.
Indian framework for radiotherapy-room licensing and fixed-installation registration.
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