Alexandra Rink

At a Glance

• Brachytherapy treatment quality is a complex metric, dependent on many factors
• Factors affecting delivered dose range from accuracy of implant and target delineation, to organ motion, filling and displacement during treatment
• Understanding and accounting for these factors are critical in delivering high quality care
• Methods of predicting organ motion and displacement can help applicator insertion and planning
• Feedback mechanism with in-vivo dosimetry is a critical component in measuring impact of these uncertainties on dose delivered

Short Bio

Dr. Alexandra Rink is a board certified Medical Physicist at Princess Margaret Cancer Centre, an Associate Professor in the Departments of Radiation Oncology and Medical Biophysics, University of Toronto and a Clinician Scientist at the Princess Margaret Research Institute. She received her B.Sc. degree with honours in Chemical Physics from the College of Physical & Engineering Science at University of Guelph in 2003, and thereafter pursued a PhD in the Department of Medical Biophysics, University of Toronto. Her thesis, supported by the National Cancer Institute of Canada through a Terry Fox Foundation Research Studentship Award, focused on using polymer materials and optical fibre read-out in order to measure radiation dose remotely during the application of radiotherapy. Upon completion of graduate studies in 2008, Dr. Rink had commenced a Medical Physics Residency program at Princess Margaret Cancer Centre with the Department of Radiation Oncology. In 2010, Dr. Rink joined the Image-Guided Interventional Radiotherapeutics for Prostate Cancer group as a Clinical Physics Fellow and in 2012 the Radiation Physics department as staff. She has been leading the brachytherapy physics group at the Princess Margaret Cancer Centre since 2013, helping implement image-guided interstitial treatments for gynaecological and prostate cancers. Dr. Rink has started her own lab in 2019, with research interest in quality improvement of brachytherapy through dosimetric measurements using in-vivo optical fibre technology, understanding and monitoring organ motion and filling, target and applicator uncertainty and the impact on dose distribution, and implant accuracy and efficiency.

Research Synopsis

In Vivo Dosimetry
Radiotherapy treatments have become very sophisticated due to advances in technology and the increased complexity of the processes themselves. A robust, real-time in vivo radiation dosimeter is an important safety system for catching errors that cannot be detected by human vigilance and other quality assurance and quality control methods. My research involves investigation of various materials for use with fibre-optical readout for real-time patient dosimetry, as well as probe and system design. An important component of this work is the ability to implement the dosimetric device on patients and accurately predict real-time dose from a linear accelerator or remote brachytherapy afterloader in order to create a quality control tool. Immediate treatment interruption upon the detection of a threshold error is critical to avoid potential health consequences, and can only be achieved with real-time data feedback and comparison against the expected. Additionally, implementing a large-scale patient dosimetry program would provide the radiotherapy community with the statistics on treatment delivery deviations, including those not resulting in severe complications.

Improvement in Brachytherapy Patient Care
The paradigm of radiotherapy delivery is scan, plan and treat. The quality of treatment depends on the applicability of the scan to the time of treatment. While in external beam radiotherapy the standard practice is to account for planning and treatment uncertainties, this is rare in high dose-rate brachytherapy. Oedema from implant and organ filling and motion are just few of the factors that can contribute to a deviation from intended dose distribution. Understanding these factors and finding methods to account for these uncertainties, for example through implementation of planning margins or by following an organ filling protocol, can help improve quality of patients’ brachytherapy treatment. Non-dosimetric factors, such as the time it takes between patient scan and treatment, or the number of treatment catheters used in brachytherapy, also play an important part in the quality of patients’ brachytherapy treatment. My research explores methods to improve these factors, including image guidance and navigation for interstitial catheter positioning. Other opportunities include assisted contouring of targets and organs. My goal is to minimize patient’s time from scan to treatment and ensure interventions performed are necessary for optimal dose delivery.

Recent Publications

• Sanmamed N., Lee J., Berlin A., Craig T., Lao B., Rink A., Bayley A., Catton C., Sundaramurthy A., Foltz W., McPartlin A., Ghai S., Gospodarowicz M., Warde P., Ménard C., Chung P. Tumor-targeted dose escalation for localized prostate cancer using MR-guided HDR brachytherapy (HDR) or integrated VMAT (IB-VMAT) boost: Dosimetry, toxicity and health related quality of life. Radiotherapy & Oncology (2020, accepted)  Coauthor or Collaborator
• Weersink RA, Qiu J, Martinez D, Rink A, Borg J, Di Tomasso A, Irish JC, Jaffray DA. Feasibility Study of Navigated Endoscopy for the Placement of High Dose Rate Brachytherapy Applicators in the Esophagus and Lung. Med Phys.(IF: 3.177) 2019 Dec 28. doi: 10.1002/mp.13997. [Epub ahead of print] Coauthor or Collaborator.
• Conway JL, Lukovic J, Ferguson SE, Zhang J, Xu W, Dhani N, Croke J, Fyles A, Milosevic M, Rink A, Rouzbahman M, Han K. Clinical Outcomes of Surgically Unresectable Endometrial Cancers. Am J Clin Oncol. (IF: 2.24) 2019 Sep 9. doi: 10.1097/COC.0000000000000600. [Epub ahead of print] Coauthor or Collaborator.
• Weersink R, Patterson S, Ballantyne H, Di Tomasso A, Borg J, Vitkin A, Rink A, Beiki-Ardakani A. An improved treatment planning and quality assurance process for Collaborative Ocular Melanoma Study eye plaque brachytherapy. Brachytherapy. (IF: 2.227). 2019 Jun 21. pii: S1538-4721(19)30035-2. doi:10.1016/j.brachy.2019.05.008. [Epub ahead of print] Coauthor or Collaborator.
• Sanmamed N, Chung P, Berlin A, Adleman J, Borg J, Lao B, Ghai S, Weersink R, Simeonov A, Rink A, Menard C, Helou J. Dose to the Bladder Neck in MRI-guided High Dose-Rate Prostate Brachytherapy: Impact on Acute Urinary Toxicity and Health-Related Quality of Life. Brachytherapy (IF: 2.227). 2019 May 17. pii: S1538-4721(18)30742-6. doi: 10.1016/j.brachy.2019.02.003. [Epub ahead of print] Coauthor or Collaborator.
• Avanzo M, Pirrone G, Mileto M, Massarut S, Stancanello J, Baradaran-Ghahfarokhi M, Rink A, Barresi L, Vinante L, Piccoli E, Trovo M, El Naqa I, Sartor G. Prediction of skin dose in low-kV intraoperative radiotherapy using machine learning models trained on results of in vivo dosimetry. Med Phys (IF: 2.884). 2019 Mar;46(3):1447-1454. doi: 10.1002/mp.13379. Epub 2019 Jan 25. Coauthor or Collaborator.
• Gerber R, Rink A, Croke J, Borg J, Beiki-Ardakani A, Fyles A, Milosevic M, Xie J, Keller H, Han K. Comparison of Dosimetric Parameters Derived from Whole Organ and Wall Contours for Bladder and Rectum in Cervical Cancer Patients Treated With Intracavitary and Interstitial Brachytherapy. Radiotherapy & Oncology. (IF: 4.942). 2018 Jun;127(3):456-459. doi: 10.1016/j.radonc.2018.01.015. Epub 2018 Feb 6. Co-Principal Author.
• Skliarenko J, Carlone M, Tanderup K, Han K, Beiki-Ardakani A, Borg J, Chan K, Croke J, Rink A, Simeonov A, Ujaimi R, Xie J, Fyles A, Milosevic M. Technique adaptation, strategic replanning, and team learning during implementation of MR-guided brachytherapy for cervical cancer. Brachytherapy. (IF: 2.227) 2018 Jan - Feb;17(1):86-93. Coauthor or Collaborator.
• Rink A, Borg J, Simeonov A, O'Leary G, Helou J, Ménard C, Chung P, Jaffray DA, Berlin A. Dosimetric impact of intrafraction changes in MR-guided high-dose-rate (HDR) brachytherapy for prostate cancer. Brachytherapy (IF: 2.227). 2018 Jan - Feb;17(1):59-67. doi: 10.1016/j.brachy.2017.06.001. Epub 2017 Jul 29. Principal Author.
• Felder S, Morley L, Ng E, Chan K, Ballantyne H, Di Tomasso A, Borg J, Bissonnette JP, Breen S, Waldron J, Rink A, Milosevic M. Brachytherapy patient safety events in an academic radiation medicine program. Brachytherapy (IF: 2.227). 2018 Jan - Feb;17(1):16-23. doi: 10.1016/j.brachy.2017.06.010. Epub 2017 Jul 27. Coauthor or Collaborator.
• Hosni A., Carlone M., Rink A., Ménard C., Chung P., Berlin A. Dosimetric feasibility of ablative dose escalated focal monotherapy with MRI-guided high-dose-rate (HDR) brachytherapy for prostate cancer. Radiotherapa & Oncology (IF: 4.9). 2017 Jan122(1): 103-108. doi: 10.1016/j/radonc/2016.11.011. Coauthor or Collaborator.
• Barbiero S., Rink A., Matteucci F., Fedele D., Paiar F., Pasqualetti F., Avanzo M. Single-Fraction Flattening Filter-Free Volumetric Modulated Arc Therapy for Lung Cancer: Dosimetric Results and Comparison with Flattened Beams Technique. Medical Dosimetry (IF: 1.123) 2016 41(4):334-338. Coauthor or Collaborator.
• Hosni A, Bezjak A, Rink A, Czarnecka K, McPartlin A, Patterson S, Saibishkumar E. High Dose Rate Brachytherapy as a Treatment Option in Endobronchial Tumors. Lung Cancer Int. 2016; 2016:3086148. (IF: 2.0) doi: 10.1155/2016/3086148. Epub 2016 Jul 14. Coauthor or Collaborator.
• Murgic J, Chung P, Berlin A, Bayley A, Warde P, Catton C, Simeonov A, Abed J, O'Leary G, Rink A, Ménard C. Lessons learned using an MRI-only workflow during high-dose-rate brachytherapy for prostate cancer. Brachytherapy (IF: 2.227). 2016 Mar-Apr;15(2):147-55. doi: 10.1016/j.brachy.2015.12.004. Epub 2016 Jan 29. Coauthor or Collaborator.
• Jaffray DA, Carlone MC, Milosevic MF, Breen SL, Stanescu T, Rink A, Alasti H, Simeonov A, Sweitzer MC, Winter JD. A facility for magnetic resonance-guided radiation therapy. Semin Radiat Oncol (IF: 4.027). 2014 Jul;24(3):193-5. doi: 10.1016/j.semradonc.2014.02.012. Coauthor or Collaborator.
• Avanzo M, Rink A, Dassie A, Massarut S, Roncadin M, Borsatti E, Capra E. In vivo dosimetry with radiochromic films in low-voltage intraoperative radiotherapy of the breast. Med Phys (IF: 2.884). 2012 May;39(5):2359-68. doi: 10.1118/1.3700175. Coauthor or Collaborator.
• Lindsay P, Rink A, Ruschin M, Jaffray D. Investigation of energy dependence of EBT and EBT-2 gafchromic film. Med Phys (IF: 2.884) . 2010 Feb;37(2):571-6. Coauthor or Collaborator.
• Rink A, Lewis DF, Varma S, Vitkin IA, Jaffray DA. Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium. Med Phys (IF: 2.884). 2008 Oct;35(10):4545-55. Principal Author.
• Rink A, Vitkin IA, Jaffray DA. Intra-irradiation changes in the signal of polymer-based dosimeter (GAFCHROMIC EBT) due to dose rate variations. Phys Med Biol (IF: 2.665). 2007 Nov 21;52(22):N523-9. Epub 2007 Oct 26. Principal Author.
• Rink A, Vitkin IA, Jaffray DA. Energy dependence (75 kVp to 18 MV) of radiochromic films assessed using a real-time optical dosimeter. Med Phys (IF: Rink A, Vitkin IA, Jaffray DA. Characterization and real-time optical measurements of the ionizing radiation dose response for a new radiochromic medium. Med Phys (IF: 2.884). 2005 Aug;32(8):2510-6. Principal Author.