Three-Dimensional Transvaginal Ultrasound for Intracavitary and Interstitial Gynecologic High-Dose-Rate Brachytherapy

Van Elburg, Devin John

Three-Dimensional Transvaginal Ultrasound for Intracavitary and Interstitial Gynecologic High-Dose-Rate Brachytherapy

dc.contributor.advisor	Meyer, Tyler
dc.contributor.advisor	Roumeliotis, Michael
dc.contributor.advisor	Plume, Rene
dc.contributor.author	Van Elburg, Devin John
dc.contributor.committeemember	Phan, Tien
dc.contributor.committeemember	Thind, Kundan
dc.contributor.committeemember	Hoover, Doug
dc.contributor.committeemember	Stosky, Jordan
dc.date	2023-11
dc.date.accessioned	2023-05-26T16:49:45Z
dc.date.available	2023-05-26T16:49:45Z
dc.date.issued	2023-05-23
dc.description.abstract	Ultrasound is prominent in prostate brachytherapy treatment workflows. While ultrasound is commonly used for applicator insertion guidance, limitations in conventional 2D ultrasound imaging restrict adoption into gynecologic brachytherapy workflows which favour MRI/CT planning. However, recent advances in 3D ultrasound imaging overcome many limitations and have more utility in gynecologic brachytherapy. In this work, we investigate clinical utility of a 3D transvaginal ultrasound (3DTVUS) in both intracavitary and interstitial gynecologic high-dose-rate brachytherapy (HDRBT) workflows. The primary limitation of ultrasound imaging is shadowing beyond inserted applicators. To overcome this, ultrasound-compatible vaginal cylinders made of sonolucent material TPX have been previously developed for 3DTVUS guidance of interstitial HDRBT implants; the cylinder was subsequently removed for the clinical vaginal cylinder for treatment. More streamlined ultrasound-based workflows are possible if treatment cylinders were ultrasound-compatible. We investigated dosimetry of TPX versus conventional materials and conclude the uncertainties introduced by TPX cylinders are clinically acceptable in gynecologic HDRBT. We developed a surrogate vaginal cylinder (SVC) which is sonolucent and geometrically matched to the multi-channel vaginal cylinder (MCVC) for intracavitary HDRBT. In theory, SVC-3DTVUS images are anatomically representative MCVC-inserted images. Therefore, the MCVC may be digitized in SVC-3DTVUS images, effectively replacing CT in the standard clinical workflow. We commissioned the SVC for MCVC intracavitary HDRBT and showed that geometric and dosimetric uncertainties are within accepted tolerances. We then implement 3DTVUS-guidance into the clinical workflow, guiding 20 combined needles across seven template interstitial HDRBT implants. The primary benefit of 3DTVUS imaging is 3D visualization of the target allowing for intraoperative assessment of implants. We qualitatively and quantitatively show that 3DTVUS impacts needles most important for target coverage and share clinician perspectives on 3DTVUS utility. Part of evaluating 3DTVUS-guided interstitial implants is assessment of vaginal dose. Despite extensive multi-institutional studies, there lacks vaginal dose metrics that reasonably correlate to toxicities due to small volume evaluation in very high dose gradient regions. We investigated small volume vaginal dose metrics and show vaginal dose metrics are reliable across different dose calculation methods when metric volumes are ≥2 cm3 and when the target volume is removed from the vaginal contour.
dc.identifier.citation	Van Elburg, D. J. (2023). Three-dimensional transvaginal ultrasound for intracavitary and interstitial gynecologic high-dose-rate brachytherapy (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/116574
dc.identifier.uri	https://dx.doi.org/10.11575/PRISM/41417
dc.language.iso	en
dc.publisher.faculty	Science
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	gynecologic brachytherapy
dc.subject	3D ultrasound
dc.subject	medical physics
dc.subject.classification	Physics
dc.subject.classification	Physics--Radiation
dc.subject.classification	Biophysics--Medical
dc.title	Three-Dimensional Transvaginal Ultrasound for Intracavitary and Interstitial Gynecologic High-Dose-Rate Brachytherapy
dc.type	doctoral thesis
thesis.degree.discipline	Physics & Astronomy
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.