IHERO UseCase 2011 In vivo patient dosimetry

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1. Proposed Workitem:

  • Proposal Editor: Juan Carlos Celi, juan-carlos.celi@iba-group.com , +49 9128 607 23
  • Reviewer: Zheng Chang, zheng.chang@duke.edu, +1 919 681-2608
  • Date: 11 May 2011 (Wiki keeps history)
  • Version: 1.0 (Wiki keeps history)
  • Domain: Radiation Oncology

2. The Problem

Patient Safety and Dose Accuracy in Radiation Oncology are important responsibilities for industry providers and healthcare professionals. Many devices, users and processes are involved in a clinical workflow and the warranty of quality highly depends on the reliability and efficiency of the patient specific QA checks and their verification. The lack of integration causes not only a lot of 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 will ensure that all the necessary steps in the process have been successfully integrated. 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. Key Use Case

The Use case has been spitted in 3 different scenarios (depending on the level of sophistication in the different departments):

  • Use Case 1 - In Vivo Patient Dosimetry with 1D detectors
  1. Patient Setup and Localization Done
  2. TMS to TDS transfer and verifications done, patient status: ready for delivery.
  3. In Vivo detectors (diodes, mosfets, etc...) in place and system ready for measurements, SW synchronized with TMS
  4. 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).
  5. Depending on tolerance criteria In Vivo Checker reports back pass/fail criteria periodically as defined in 4.
  6. Alternatively this comparison is done at TMS.
  7. TMS notifies users the failure of the In Vivo check and the cause(s)

Samples of the interconnectivity needed for this use case:

  1. TMS download treatment machine parameters to 3rd party In Vivo System
  2. Alternatively TPS download Dosimetry parameters to 3rd party In Vivo System
  3. In Vivo System computes doses and compares it with the TPS data and download results back to TMS: In Vivo checks
  4. Manual entry in vivo result into TMS if interconnectivity between the In Vivo System and TMS doesn’t exist.

Assumptions:

  1. Configuration and Calibration data for different detectors are available and configurable in the In Vivo Checker.
  2. System is able to recognize different detectors when they are exchanged.
  3. 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
  4. TMS can generate reports on delivered doses.
  • Use Case 2 - In Vivo Patient Dosimetry with 2D area detectors (transmission, EPID, etc...)
  1. Patient Setup and Localization Done
  2. TMS to TDS transfer and verifications done, patient status: ready for delivery.
  3. EPID or transmission Detector ready and configured for In Vivo Dosimetry, SW synchronized with TMS or TPS (download dosimetry parameters)
  4. 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).
  5. 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.
  6. Alternatively this comparison is done at TMS.
  7. Alternatively in Vivo Checker performs 3D Dose reconstruction and compares with Original plan (assumes CBCT capabilities).
  8. TMS notifies users the failure of the In Vivo check and the cause(s)

Samples of the interconnectivity needed for this use case:

  1. TMS download treatment plan and fraction information to In Vivo Checker
  2. Alternatively TPS download Dosimetry parameters to In Vivo Checker
  3. In Vivo System computes doses and compares it with the TPS data and download results back to TMS.
  4. Alternatively a system compares fluences field by field.
  5. Manual entry in vivo result into TMS if interconnectivity between the In Vivo System and TMS doesn’t exist.

Assumptions:

  1. 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.
  2. 2D fluence plans can therefore be reconstructed for either analysis using tools like gamma functions or for Dose reconstructions.
  3. Configuration and Calibration data for Dosimetry are available and configurable in the EPID or 2D Transmission Dosimetry system
  4. System is able to recognize different detectors if they are exchanged
  5. Proper instructions shall be provided to guide therapists to accomplish the task, eg. Expected tolerance criteria.

TMS can generate reports on delivered doses

  • Use Case 3 - In Vivo Patient Dosimetry based on log files from Linear Accelerator

This use case is similar to Use Case number 2, however Fluences are reconstructed from machine log files during delivery process.

4. 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.

5. Discussion

<Include additional discussion or consider a few details which might be useful for the detailed proposal>

<Why IHE would be a good venue to solve the problem and what you think IHE should do to solve it.>
<What might the IHE technical approach be? Existing Actors? New Transactions? Additional Profiles?>
<What are some of the risks or open issues to be addressed?>