Quality & Safety Considerationsin Stereotactic Radiosurgery and Stereotactic B ody Radiation Therapy. Introduction. SRS is well established in cranial neoplasms achieving high local control rates and minimal toxicities.
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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 Minimize radiation related injury in adjacent normal tissue Maximize cell-killing effect
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.