The Physicist’s Role in Developing a Stereotactic Radiosurgery Program

Stereotactic radiosurgery (SRS) is a highly precise form of radiation therapy used to treat selected intracranial lesions, vascular malformations and functional disorders. Although the name suggests surgery, treatment is delivered without an incision, using tightly focused radiation in one or a small number of fractions. Its success depends on a carefully integrated clinical, technical and safety program.

The medical physicist is central to that integration. Their responsibilities extend from business planning and equipment selection to image registration, treatment planning, commissioning, quality assurance and incident learning. They also help the clinical team decide when a new technique is genuinely ready for patient use rather than merely technically possible.

The archived Canadian Organization of Medical Physicists meeting site provides a useful professional context for this work. A scientific meeting brings together practical experience in clinical implementation, adaptive radiotherapy, dosimetry and governance—topics that remain relevant to Australian departments developing or expanding stereotactic services.

For an Australian service, the local setting matters. A program in Sydney or Melbourne may have access to specialist neurosurgery and oncology networks, while a regional centre may need referral pathways across long distances. Staffing availability, state radiation legislation, accreditation expectations and the cost of maintaining advanced imaging all shape the final model.

Defining the Clinical Service

A physicist should help define the intended scope before any hardware is purchased. The service might begin with brain metastases, vestibular schwannoma and arteriovenous malformations, then expand to selected extracranial stereotactic body radiotherapy cases. Each indication requires clear limits for lesion size, location, motion, dose, fractionation and proximity to sensitive structures.

This early work should involve radiation oncologists, neurosurgeons, radiologists, radiation therapists, nurses, IT specialists and hospital executives. It should also identify referral volumes and whether the service will support public patients, private patients or both. In Australia, a realistic business case must account for capital expenditure, Medicare funding arrangements, private health billing and the cost of specialist service contracts.

The physicist can translate clinical ambition into measurable requirements. These may include image guidance tolerances, couch movement accuracy, small-field dosimetry performance, treatment time, backup arrangements and acceptable downtime. A written scope prevents the program from becoming dependent on individual enthusiasm or a single vendor’s demonstration.

Designing the Technical Architecture

SRS may be delivered on a dedicated radiosurgery system, a conventional linear accelerator with stereotactic capability, or a robotic platform. The physicist evaluates beam energy, multileaf collimator design, cone options, imaging systems, couch accuracy and integration with the treatment planning system. The best choice is the one that fits the department’s clinical workload and support capacity.

Commissioning must establish confidence in the complete chain, not just the radiation output. Small-field measurements, detector selection, beam modelling, end-to-end tests and independent dose verification are essential. Mechanical checks should cover gantry, collimator, couch, imaging geometry and immobilisation interfaces, because a small positional error can have a large clinical effect.

Australian departments also need to consider supply and support realities. A service located outside Sydney, Melbourne or Brisbane may face longer waits for engineers, replacement parts and specialist applications support. The physicist should build realistic contingency plans, including alternative treatment techniques, shared arrangements with nearby centres and procedures for managing equipment failure.

Managing Imaging and Treatment Planning

High-quality imaging is the foundation of stereotactic accuracy. Thin-slice planning CT, MRI fusion and, where appropriate, angiographic or functional imaging must be acquired using reproducible protocols. Distortion assessment is particularly important for MRI, since geometric errors can alter target definition and organ-at-risk boundaries.

The physicist works with radiologists and radiation oncologists to establish image registration methods and to decide when rigid registration is adequate. For complex anatomy, deformable registration may assist review but should not be treated as an unquestioned substitute for expert anatomical assessment. The workflow should preserve registration information and make image-origin assumptions visible to every clinician.

A related area of interest is MR-guided adaptive radiotherapy, which illustrates how imaging, planning and delivery can become a single clinical process. While online adaptation is not required for every SRS service, the same principle applies: the team must understand how image quality, anatomy and treatment decisions interact at the point of care.

Establishing Safety and Quality Governance

SRS requires layered safety controls because high doses are delivered to small targets with limited opportunity for correction. The physicist should help create independent checks for prescription, imaging, contouring, planning, plan approval, patient identity, immobilisation and treatment delivery. A formal time-out before treatment can confirm target, dose, fractionation and image guidance details.

Quality assurance should combine daily, monthly and annual tests with patient-specific verification. The exact schedule should be risk-based and consistent with local policy, professional guidance and equipment capability. In Australia, the program must also align with applicable state or territory radiation control legislation, hospital governance requirements and the expectations of regulators such as the Australian Radiation Protection and Nuclear Safety Agency where relevant.

Incident reporting should be treated as a learning system rather than a search for blame. Near misses involving incorrect image sets, incomplete immobilisation or planning errors can reveal weaknesses before patient harm occurs. Regular review of these events helps the physicist identify recurring problems in software, communication, workload or training.

Building the Operational Workflow

A safe program depends on a predictable pathway from referral to follow-up. The physicist should help map every handover, define who can authorise exceptions and ensure that urgent cases do not bypass essential checks. This is especially important when a patient travels from a regional town to a metropolitan centre and has limited opportunities for repeat imaging or replanning.

Practical operating details include fasting instructions where relevant, medication review, immobilisation preparation, MRI safety screening and arrangements for patients who are anxious or unable to remain still. Australian departments should consider long travel times, hot summer conditions and public transport disruption when setting appointment schedules. A patient arriving late after several hours of travel may need a clear escalation process rather than informal workarounds.

A concise operational checklist can keep the service consistent:

• Confirm referral criteria, imaging requirements and contraindications
• Verify immobilisation, image fusion and target-volume documentation
• Complete independent plan and dose checks before treatment
• Record machine, software and patient-specific QA results
• Define follow-up, incident review and equipment downtime pathways

Developing the People and the Culture

Technology cannot compensate for an inexperienced or poorly coordinated team. The physicist contributes to competency frameworks for radiation therapists, planners, clinicians and junior physicists. Training should include supervised cases, emergency procedures, image-guidance review and practical exercises involving failed checks or equipment faults.

The service also needs a sustainable staffing model. A single physicist who performs commissioning, routine QA, troubleshooting and clinical support may become a hidden point of failure. Australian centres should consider leave coverage, professional development, after-hours expectations and access to external expertise. Collaboration through ACPSEM networks and relationships with larger metropolitan departments can support smaller services.

Professional meetings and archived scientific resources can inform this development, but local adaptation remains essential. Before delegates review conference registration or plan attendance at a scientific meeting, the department should identify the questions it needs answered: commissioning approaches, small-field measurement methods, credentialing, workflow design or lessons from reported incidents.

Measuring Performance and Sustaining the Program

Once the first patients have been treated, the physicist should help monitor whether the service performs as intended. Useful measures include treatment interruptions, image-guidance deviations, plan approval times, repeat imaging, near misses, patient waiting times and equipment availability. Clinical outcomes and patient-reported experience should be reviewed alongside technical indicators.

A mature program also revisits its scope. New software, adaptive methods, surface guidance or improved imaging may offer benefits, but every change requires a documented risk assessment and appropriate validation. The local market matters here: an expensive upgrade may be justified in a high-volume Melbourne centre but difficult to sustain in a smaller regional service without shared access or vendor support.

Long-term resilience can be supported by a focused set of priorities:

• Review clinical indications and referral volumes each year
• Audit end-to-end accuracy and patient-specific QA trends
• Maintain current procedures for state and territory compliance
• Budget for software licences, service contracts and staff training
• Share lessons through professional networks and multidisciplinary review

A stereotactic radiosurgery program succeeds when precision becomes a property of the whole service rather than a claim attached to one machine. The medical physicist provides the technical leadership, risk management and evidence-based discipline that connect clinical intent with dependable treatment delivery.

Australian departments can use that role to build services suited to their own geography, workforce and patient population. Begin with a defined clinical scope, involve the physicist in decisions from the earliest business case, and test every stage of the pathway before routine treatment begins.