Quality & Safety Considerationsin Stereotactic Radiosurgery and Stereotactic Body Radiation Therapy

Introduction

SRS is well established in cranial neoplasms achieving high local control rates and minimal toxicities.

SBRT is much more recent but results from multi-institutional trials have yielded similar results. Selected early stage cancers Oligometastases Recurrent disease in previously radiated field

SBRT

High degree of anatomic targeting accuracy and reproducibility

High doses of precisely delivered radiation

Maximize cell-killing effectMinimize radiation related injury in adjacent normal tissue

SBRT

Special attention and diligence is required for delivery of SBRT due to very small margin of error.

Errors in measurement of output factors affected 145 patients in Toulouse, France 2006 – 2007.

31% 12-mth actuarial rate of trigeminal neuropathy in 32 acoustic neuroma patients overdosed.

Fundamental Elements of SRS and SBRT safety and quality

Immobilization, simulation, treatment planning, delivery and quality assurance is unique in each disease site.

Fundamental Elements of SRS and SBRT safety and quality

Multidisciplinary working environment fostering Clear communication Guards against inappropriate interruptions Careful planning Thorough risk assessment

Fundamental Elements of SRS and SBRT safety and quality

Thorough review of all resources including staffing levels and skills

Training of all personnel including: Training in quality management Safety practices Program-specific education

Development of quality assurance processes that encompass all clinical and technical program aspects.

Fundamental Elements of SRS and SBRT safety and quality

Development of: Checklists Processes for documentation and reporting Peer review Regular review of processes and procedures Updating of clinical guidelines and

recommendations Ongoing needs assessment Continuous quality improvement

Personnel Considerations

Large commitment of resources required.

Coordinated efforts of properly trained individuals required to evaluate each patient and plan the treatment Radiation oncologists, medical physicists,

dosimetrists, radiation therapists

Other physicians can offer unique subspecialty expertise Neurosurgeons, oncologic surgeons

Personnel Considerations

Initial training of personnel should be stepwise and via a structured education program.

Training on SBRT technologists including training by vendor(s) is an essential element.

Technical Considerations

Ablative doses of radiation coupled with small margins around CTVs require image guidance and motion management strategy.

Large numbers of non-opposing, often non-axial approaches through complex heterogeneities so doses need to be calculated accurately.

Isocenter placements are complex.

Technical Considerations

Simulation Custom formed devices that cover a large extent of

patient above and below the tumour for immobilization.

Anciliary localization and position monitoring technologies such as surface imaging techniques, implanted radiographic markers specific to tumour sites.

Image guidance strategies such as 4D computed tomography, soft tissue MRI imaging, metabolic information.

Acceptance and commissioning

Acceptance testing is performed in cooperation with equipment vendor to ensure equipment is operating within stated specifications and in compliance with regulatory requirements.

Acceptance and commissioning

Commissioning task includes measurement of radiation characteristics of the machine Beam data acquisition involving small size of fields may

be challenging and require appropriately small detectors.

Independent assessment of small field measurements may be essential and include comparison against published data, verifying data through completely independent set of measurements.

Independent verification of the absolute calibration, utilizing service by the Radiologic Physics Center is essential.

Acceptance and commissioning

Accurate calculation of dose and monitor units must be ensured. Systematic comparison of calculation and

measurement ranging from simple configurations to sophisticated beam arrangements.

Facilitated by site-specific anthropomorphic phantoms.

Acceptance and commissioning

Canadian Association of Provincial Cancer Agencies Stereotactic Radiosurgery – Radiotherapy Standards ‘It is essential to recognize that commissioning SRS/T

techniques involves more than just ensuring that the equipment itself works properly. The whole treatment chain, including the measuring, imaging modalities and treatment planning system must be tested in addition o the delivery unit and SRS/T tools.’

The Quality Assurance Program

Robust QA is crucial and must continuously evolve.

‘The complexity, variation in individual practice patterns, and continued evolution of stereotactic-related technology can render a static, prescriptive QA paradihm insufficient over time.’

Recommendations for stakeholders

Vendors Understand the needs and requirements of the

clinicians, medical physicists and radiation therapists Incorporate features and safeguards to assure

efficacious and safe operation of their products. Provide opportunities for specialized training,

emphasizing clinical implementation and quality assurance (Not just equipment QA but process QA).

If more than one manufacturer involved, onus is on them to collaborate and ensure compatibility of their systems to ensure safe operation.

Recommendations for stakeholders

Professional organizations Allocate resources to facilitate proper training in

specialized procedures. Specialized accreditation programs

Recommendations for stakeholders

Government agencies Centralized registries for event reporting, such as

those mandated by law in the United Kingdom, ensure appropriate transparency and provide effective mechanism for all stakeholders to learn from errors.

Summary

Team based approach

Appropriately trained and credentialed specialists.

Significant resources in personnel, specialized technology and implementation time required.

Thorough feasibility analysis needed.

Feasibility and planning discussions needed prior to undertaking new disease sites.

Summary

Acceptance and commissioning protocols and test must explore every aspect of individual and integrated systems.

Comprehensive QA program encompassing all clinical, technical and patient specific treatment aspects.

All stakeholders must demonstrate clear commitment and work closely together to ensure highest level of patient safety and efficacy in SBRT.