In Vivo Patient Dosimetry: Ensuring Accuracy in Radiation Oncology

1. IHE-RO Integrating the Health Care Enterprise- Radiation Oncology Use Case: In Vivo Patient Dosimetry Editor: Juan Carlos Celi - IBA Reviewer: Zheng Chang – Duke University

2. Rationale • Patient Safety and Dose Accuracy are one of the most important responsibilities in Radiation Oncology. • Different devices, users and processes are involved in the complete workflow; full integration of different components as well as their warranty of quality highly depend on the reliability and efficiency of the patient specific QA checks and their verification. • Lack of integration: • manual work for clinicians but also an • increased risk of errors and mistreatments to be avoided. • Modern technologies must provide technical solutions that are easy to implement in a broad scale. • Pre-treatment verifications ensure process integrity. However the ultimate goal of Radiation Oncology is to ensure that the radiation doses delivered to Tumor and Normal tissues match the planned – prescribed ones fraction by fraction.

3. Use Case • The Use case has been separated in 3 levels of complexity, 3 use cases: • Use Case 1: In Vivo Patient Dosimetry with 1D detectors: • Use Case 2: In Vivo Patient Dosimetry with 2D area detectors (transmission, EPID, etc...) • Use Case 3: In Vivo Patient Dosimetry based on log files from Linear Accelerator • They depend on levels of complexity in the workflow as well as hospital preferences in QA. • STATUS: First version created and loaded to wiki.

4. Use Case 1: In Vivo Patient Dosimetry with 1D detectors: • Patient Setup and Localization Done • TMS to TDS transfer and verifications done, patient status: ready for delivery. • In Vivo detectors (diodes, mosfets, etc...) in place and system ready for measurements, SW synchronized with TMS • Treatment Starts, TMS and In Vivo measurements synchronized (each gantry position for Conformal and IMRT, each control point or 4-5 degrees in Rotational techniques). • Depending on tolerance criteria In Vivo Checker reports back pass/fail criteria periodically as defined in 4. • Alternatively this comparison is done at TMS. • TMS notifies/records users the failure of the In Vivo check and the cause(s)

5. Use Case 2: In Vivo Patient Dosimetry with 2D area detectors (transmission, EPID, etc...) • Patient Setup and Localization Done • TMS to TDS transfer and verifications done, patient status: ready for delivery. • EPID or transmission Detector ready and configured for In Vivo Dosimetry, SW synchronized with TMS or TPS (download dosimetry parameters) • Treatment Starts, TMS and In Vivo measurements synchronized (each gantry position for Conformal and IMRT, each control point or 4-5 degrees in Rotational techniques). • 2D Area detector system compares expected fluences (from TMS or TPS) versus delivered (measured) and Depending on tolerance criteria In Vivo Checker reports back pass/fail criteria periodically as defined in 4. • Alternatively this comparison is done at TMS. • Alternatively in Vivo Checker performs 3D Dose reconstruction and compares with Original plan (assumes CBCT capabilities). • TMS notifies users the failure of the In Vivo check and the cause(s) • This use case is similar to Use Case number 2, however Fluences are reconstructed from machine log files during delivery process. Use Case 3: In Vivo Patient Dosimetry based on log files from Linear Accelerator

6. General Assumptions • Configuration and Calibration data for different detectors are available and configurable in the In Vivo Checker. • System is able to recognize different detectors when they are exchanged. • Proper instructions shall be provided to guide therapists to accomplish the task, eg. Picture of placement of the detector can be loaded into the TMS • TMS can generate reports on delivered doses. • Additional to Use Case 2 • This case is based on the capacity to include in the clinical workflow the uses of EPID / Transmission Detectors for direct and in-vivo dose verifications. • 2D fluence plans can therefore be reconstructed for either analysis using tools like gamma functions or for Dose reconstructions. Standards & Systems • As IHE-RO addresses interoperability, not functionality, the integration profile must be defined along these lines .DICOM RT standard (data objects and worklist) should be considered in implementation of the integration profile. One of the main objectives is to get the QA vendors to join the IHE-RO efforts, and get these QA tools to be part of clinical workflow. • Therefore the Use of DICOM RT standards are of big help.