Systematic Review of Intensity-Modulated Brachytherapy (IMBT): Static and Dynamic Techniques

Abstract

Purpose: To systematically review scientific literature on the use of intensity-modulated brachytherapy (IMBT), including static and dynamic shielding approaches, to enhance therapeutic ratio. Studies were evaluated for technique, disease site, dosimetry, applicators, dosimetric calculations, and planning algorithms. Comparisons with standard-of-care brachytherapy techniques, alternative IMBT methods, or both were performed for dose-to-target volumes, organs at risk (OARs), and treatment planning or delivery times. Methods and Materials: Inclusion criteria were any peer-reviewed journal articles on IMBT published from January 1, 1980, to January 1, 2019, on PubMed, Google Scholar, Cochrane Library, and EBSCO databases. Two independent investigators reviewed each article for inclusion and exclusion criteria and scope. Data collected on each study included technique, source or shield material, disease site, n of study (n Z number of simulated plans/treated patients), doseto-target/OARs, and planning or delivery times. This review adhered to the Preferred Reporting Items for Systemic reviews and Meta Analyses (PRISMA). Results: Database queries yielded 1734 results, which were reduced to 436 after exclusion criteria and 78 peer-reviewed journal articles after evaluation of scope. Studies per disease site were 31 for cervical; 16 for rectal; 10 for oculocutaneous; 7 for breast; 6 for prostate; and 8 for other, multiple, or no specific disease site. Eighteen studies demonstrated a significant decrease in dose to OARs (5.1%-68.2%), 11 improved treatment planning or delivery times (7.6%-99.7%), and 6 increased target coverage (18.6%-71.6%) relative to standard-of-care or alternative IMBT technique. IMBT consistently decreased dose to OAR compared with the standard of care at the cost of increased planning or delivery times. Innovations in dose calculation or planning algorithms and applicators were capable of ameliorating prolonged treatment intervals.

Determinants of Sensitivity to Radiotherapy in Endometrial Cancer

“…Both IMRT and VMAT have a good balance benefit/risk in EC compared to conventional conformal RT [ 129 ]. Like EBRT, BT has evolved into intensity-modulated BT (IMBT), 3D and 4D-IGBT, having the same promises and drawbacks as IMRT and IGRT [ 130 ]. Both 3D and 4D-IGBT have shown good local control for women with recurrent EC [ 131 , 132 ] and a 3D-EGBT high response rate in inoperable early stage endometrioid EC [ 133 ].…”

Monte Carlo dosimetric characterization of a new high dose rate Yb brachytherapy source and independent verification using a multipoint plastic scintillator detector

“…10 For IMBT treatment planning, MC-generated dose distributions are typically used as inputs for the optimization algorithm during inverse optimization. 6 Several detectors have been studied to assess the dose delivery during a brachytherapy treatment. Plastic scintillator detectors (PSDs) show promise for obtaining accurate dose measurements in brachytherapy.…”

“…Intensity modulated brachytherapy (IMBT) is a brachytherapy technique that can be delivered using a shielded applicator or source to modulate the dose distribution 6 . Static and dynamic IMBT approaches can be used to modulate the dose distribution to the shape of the tumor, reduce the dose to organs at risk, provide a method for dose escalation, or allow for fewer catheters to be implanted.…”

Commentary on Systematic Review of Intensity Modulated Brachytherapy (IMBT): Static and Dynamic Techniques

“…In this issue of the Red Journal, Dr Callaghan and associates provide a systematic review of intensity modulated brachytherapy (IMBT) technology and the state of its development. 1 IMBT, as referred to in the paper, specifies those radiation sources and applicators designs that use metallic shields to create anisotropic "directional" radiation profiles of varying degrees, as opposed to the familiar isotropic dose distribution widely used and described in American Association of Physicists in Medicine TG43, 2 to create brachytherapy plans of high quality. They further categorize IMBT technology into static versus dynamic techniques; if the shield moves during treatment delivery, the technology is classified as the latter as opposed to the former if it is immobile.…”

“…Since Ebert's paper, there has been tremendous progress in this line of research; numerous and progressive IMBT system designs have been proposed and have shown impressive theoretical benefit in terms of better target coverage (18.6%-71.6%) and decreased normal tissue dose (5.1%-68.2%). 1 2. The brachytherapy field in general has recently seen fast uptake of 3-dimensional imaging (magnetic resonance [MR]/computed tomography/ultrasound) along with perfraction adaptive replanning practice, embracing a true image guided adaptive brachytherapy workflow.…”