A Practical Approach to Commissioning a 3D Scanner for Brachytherapy

Brachytherapy treatment has evolved rapidly over the past decade, moving away from two-dimensional planning toward fully three-dimensional image-guided workflows. Modern scanners now allow clinical teams to capture applicator geometry, patient surface contours, and custom-printed moulds with millimetric accuracy. Commissioning these devices properly is not a bureaucratic exercise; it is the foundation on which safe, accurate dose delivery rests. For Australian centres operating under the Australian Radiation Protection and Nuclear Safety Agency framework, rigorous commissioning also demonstrates compliance with national safety codes.

Practitioners who have travelled to international meetings know how valuable peer-reviewed protocols can be. The following sections walk through a practical, step-by-step approach to bringing a new 3D scanner into clinical service for brachytherapy, drawing on lessons shared at forums such as the COMP Annual Scientific Meeting and refined through local experience in Sydney, Melbourne, and Perth.

Understanding the clinical role of the scanner

Before unboxing the hardware, the commissioning team must clearly define what the scanner will be used for. Common applications include capturing the external contour of a patient for superficial or interstitial treatments, digitising custom surface applicators, and verifying the position of templates or needles before planning. Each use case places different demands on spatial resolution, acquisition speed, and integration with the treatment planning system. A surface scanner used for custom bolus fabrication, for example, requires excellent accuracy over a curved geometry, while a scanner used to digitise needle positions may prioritise point cloud precision over surface texture.

In Australia, where many regional centres serve vast catchment areas, choosing a device with robust remote support capabilities has practical value. Vendors offering secure remote diagnostics and software updates reduce the need for costly site visits and help maintain uptime across busy public hospital networks, particularly in remote parts of Queensland and Western Australia where engineer travel can take days to arrange.

Facility preparation and site readiness

Physical installation begins with a site survey. Most structured-light and laser scanners operate reliably between 18 °C and 28 °C, so the scanner room should have stable temperature control and low humidity. Lighting matters too: many optical systems struggle under direct sunlight or fluctuating ambient conditions. Blackout blinds or fixed-wavelength LED panels are common solutions.

Australian electrical installations run at 230 V and 50 Hz, and most clinical-grade scanners are supplied with region-specific power cords. Check that the uninterruptible power supply rating matches the scanner's peak draw, and that the network drops support the bandwidth required for transferring large surface mesh files to the planning system. For departments in Brisbane or Adelaide that share IT infrastructure with other hospital systems, early engagement with the local biomedical engineering group avoids delays during commissioning week.

Geometric calibration and accuracy testing

The heart of commissioning is geometric verification. A calibrated test phantom containing fiducial markers of known separation is scanned multiple times from different orientations. The resulting point clouds are compared against the manufacturer's specification using software such as 3D Slicer or in-house validation scripts. Acceptable tolerances vary by application, but a typical target for high-dose-rate brachytherapy surface scanning is sub-millimetre mean distance error with a maximum deviation below 1.5 mm across the working volume.

It is also worth assessing the scanner's performance on surfaces with different reflectance properties. Clear plastic applicators, matte silicone moulds, and skin all behave differently under structured light. Documenting these responses helps physicists advise clinicians on when a spray-on contrast agent or alternative imaging modality is appropriate. ACPSEM members frequently share these phantom protocols through the college's special interest groups, which is a useful starting point for new centres building local validation libraries.

Software configuration and workflow integration

Once hardware performance is confirmed, attention turns to software. The scanner must export data in a format that the treatment planning system can ingest, typically DICOM Surface Segmentation or an STL mesh that can be converted downstream. Commissioning should verify not only file integrity but also coordinate system consistency; a mesh exported with an arbitrary origin must align correctly with the planning CT.

This is also the stage to address cybersecurity. Patient surface data are identifiable, and any device connected to the hospital network must comply with the local information security policy. Engineers commissioning a new scanner should confirm that data transfer uses encrypted channels, that user authentication integrates with the hospital's active directory, and that audit logs capture every access event. Colleagues interested in the broader topic of data protection may wish to read the companion piece on securing patient information in medical physics environments.

End-to-end testing with anthropomorphic phantoms

Geometric and software tests confirm that the scanner works, but end-to-end testing confirms that it works for brachytherapy. An anthropomorphic pelvis or breast phantom, fitted with brachytherapy catheters and loaded with radioactive sources on the afterloader, exercises the entire chain from scanning to dose calculation. The physicist compares the planned dose distribution based on the scanned geometry against an independent calculation, typically performed using a second commercial system or a Monte Carlo reference.

End-to-end testing is also the ideal time to refine standard operating procedures. How long does a full scan take? Where does the patient sit or lie? Which staff member operates the scanner, and how is the data labelled and archived? Documenting these answers in the commissioning report provides a useful training resource once the device enters routine service, and helps new registrars and radiation therapists become confident users during their first weeks on the brachytherapy rotation.

Commissioning documentation and ongoing quality assurance

The commissioning report is the lasting evidence that the scanner is fit for clinical use. Under ARPANSA's Code of Practice for radiation oncology and the related state-based legislation, facilities must maintain documented evidence of equipment performance, staff competency, and quality assurance schedules. A well-organised report should include the purchase specification, installation records, calibration certificates, test results with statistical analysis, software version history, and a baseline image dataset for future comparisons.

Ongoing QA should be proportionate to risk. A quick daily check using a simple geometric phantom is often sufficient to catch drift or damage, with more comprehensive quarterly tests examining accuracy, noise, and reproducibility. Linking these QA records to the facility's broader quality management system ensures that trends are visible to the radiation safety officer and that any out-of-tolerance results trigger a predefined response.

Teams preparing to refresh their commissioning protocols will find it valuable to connect with peers at the upcoming scientific meetings. Delegates attending the Banff gathering can review the accomodations options when planning their trip, and the abstract archive offers numerous examples of scanner validation studies from colleagues across the Asia-Pacific region.