The Development of an Autonomous Robotic Surgical Framework for Breast Brachytherapy

• Author / Creator

  Afshar, Mehrnoosh

• Low-dose-rate-permanent-seed (LDR-PS) brachytherapy is a minimally inva-
  sive radiotherapy technique used after breast lumpectomy to prevent the re-
  growth of cancerous cells around the margins of a hollowed-out tumor (seroma).
  This approach involves implanting multiple radioactive seeds (each measuring
  2-3mm in length) in and around the seroma, gradually irradiating and elimi-
  nating any remaining cancerous cells. LDR-PS brachytherapy has had signif-
  icant success in treating prostate cancer and is now being explored for breast
  cancer treatment. However, it has a more established history in the former.
  During LDR-PS, the seeds are implanted into the breast using 6-20 fine
  flexible needles under ultrasound (US) imaging, following a pre-operative plan
  derived from dosimetry calculations based on the patient’s medical images
  (usually Computed Tomography or CT). Besides its clinical benefits over other
  radiotherapy methods like external beam radiation, LDR-PS promotes health-
  care equity and inclusion by reducing frequent hospital visits, benefiting both
  rural and urban patients.
  However, the adoption of LDR-PS brachytherapy has encountered chal-
  lenges. One significant limitation is the requirement for surgeons to undergo
  substantial training for accurate seed implantation, particularly in breast can-
  cer cases. Inaccurate placement of seeds during breast brachytherapy is pri-
  marily due to two factors: (1) the discrepancy between the intraoperative
  ultrasound images and the pre-operative CT/MRI images caused by breast
  tissue deformation, and (2) the utilization of non-specialized surgical tools
  and techniques designed for prostate surgery. Incorrect seed implantation can
  lead to inadequate radiotherapy and increased cancer recurrence risk. Ad-
  ditionally, using instruments intended for prostate surgery is inappropriate
  due to the breast’s mobility and compliance, as well as the needle’s limited
  maneuverability due to its shorter insertion length.
  This study explores the potential benefits of incorporating an Assistive
  Robotic Surgical System (ARSS) in the context of LDR-PS brachytherapy
  surgery. The research focuses on addressing the complexities of the surgical
  environment, which undergoes deformation due to surgical interactions and
  necessitates patient-specific tuning. The study presents a comprehensive ap-
  proach to developing a simulation environment suitable for ARSS, beginning
  with pre-operative design and demonstrating its effectiveness in active defor-
  mation control during LDR-PS brachytherapy surgery. Moreover, the study
  investigates methods for updating the pre-operative model intra-operatively
  and explores the use of a robotic arm for US-probe manipulation. The re-
  search provides valuable insights into the potential applications of ARSS in
  enhancing the performance of LDR-PS brachytherapy surgery. The main con-
  tributions of this thesis are as follows:
  Active tissue deformation for target manipulation: This research tackles
  the lack of real-time nonlinear tissue modeling integrated into a control frame-
  work for tissue manipulation. The study demonstrates the integration of a
  real-time deformable tissue solver into the control loop, enabling effective tar-
  get manipulation.
  Intra-operative model updates for target tracking: Two methods are de-
  veloped to improve the accuracy of target tracking based on patient-specific
  biomechanical models. The first method, KF-ADMM, incorporates data into
  an ADMM-based Finite Element Method (FEM) solver through Kalman Fil-
  tering. The second method utilizes a generative variational autoencoder struc-
  ture based on graph neural networks (GNN-VAE) to reduce the dimensionality
  of the input mesh. The Ensemble Smoother with Multiple Data Assimilation
  (ES-MDA) is employed for simultaneous updates, enhancing the corrective ca-
  pability of the KF-ADMM method. Robot-assisted US probe manipulation:
  The study utilizes a Panda dexterous robotic arm to control the US probe,
  accurately following the needle tip.
  Overall, this research advances the field of ARSS in LDR-PS brachytherapy
  surgery by addressing tissue manipulation, target tracking, sim-to-real regis-
  tration, and robot-assisted US probe manipulation. The findings highlight the
  potential to improve the performance and precision of LDR-PS brachytherapy
  procedures, particularly in complex surgical environments.

• Subjects / Keywords

  • Medical Robotics

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-0z0b-h588

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.