Dosimetric characterization of a new directional low‐dose rate brachytherapy source

Aima, Manik; DeWerd, Larry A.; Mitch, Michael G.; Hammer, Clifford G.; Culberson, Wesley S.

doi:10.1002/mp.12994

Cited by 8 publications

(14 citation statements)

References 30 publications

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“…"Static" techniques included any shielded technique in which the shield did not move relative to the source or regions of interest during treatment. The shield could be associated with the applicator or the source directly (subcategories "static-shielded applicators" [46][47][48][49] and "static-shielded sources," [53][54][55][56][57][58][59][60][61][62][63][64] respectively), but a given approach was not included if a static shield was solely associated with an OAR for its sparing and not with the source or applicator (eg, mandibular shields in head and neck BT). Techniques were considered "dynamic" if the shield was translated or rotated during treatment relative to the source or regions of interest as part of the treatment plan.…”

Section: Imbt Per Techniquementioning

confidence: 99%

“…1B), 53,56,57,59,61,64 or intraoperative BT for pancreatic, abdominopelvic, and colorectal cancer. 54,55,58,62,63 Lin et al introduced directional D-shaped 125 I sources with a 0.2 mm-thick gold shield for interstitial LDR-BT to achieve an angular uniform dose over a 180-degree sector around the axis of the source in the transverse plane. 60 They reported dosimetric validation results for breast cancer when compared with 192 Irbased high-dose-rate (HDR)-BT plans, and the treatmentplanning technique for the directional, D-shaped LDR source (Fig.…”

Section: Static-shielded Imbtmentioning

confidence: 99%

“…They also developed a planar CivaDot array called CivaSheet, whose sheets are 5 cm 2 wide Â 15 cm 2 long, with 8-mm spacing between the center of each CivaDot, yielding 108 dots in 18 rows of 6 dots each. 54 The sheet can be cut according to the size of the treatment area. Each CivaDot is oriented such that the gold shields are all on the same side of the CivaSheet, yielding a hot and cold side of the sheet.…”

Section: Static-shielded Imbtmentioning

confidence: 99%

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

Callaghan

Adams

Flynn

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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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.

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Section: Imbt Per Techniquementioning

confidence: 99%

Section: Static-shielded Imbtmentioning

confidence: 99%

Section: Static-shielded Imbtmentioning

confidence: 99%

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

Callaghan

Adams

Flynn

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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“…Under the assumption of a planar implant, the individual CivaDot strength to be ordered can be determined using published nomograms . Traceable air‐kerma strength measurements for this directional source are conducted using standard source acceptance protocol and equipment . It is, however, necessary to use a specially designed CivaDot holder that allows accurate source rotation around the axis of the well‐chamber, while preserving perpendicular orientation of the source surface and maintaining the location of the active volume on the axis …”

Section: Introductionmentioning

confidence: 99%

“…As a result, the value of Λ = 0.579(17) cGy/h/U is lower than that of an unshielded

^{103}

Pd source (typically about 0.68 cGy/h/U) . Radiochromic film measurements have been used to benchmark the directional source model, derived from MCNP6 Monte Carlo simulations …”

Section: Introductionmentioning

confidence: 99%

Application of a directional palladium‐103 brachytherapy device on a curved surface

Veltchev¹,

Price²,

Chen³

et al. 2019

Medical Physics

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Purpose: The directional planar palladium-103 LDR device (CivaSheet TM ) may be used for intraoperative implantation at the interface between the tumor site and healthy tissue. Its dosimetric properties have been studied in the ideal case of application on a flat surface. The dosimetric impact of implanting this highly directional device on a curved surface that may be encountered in clinical treatments is analyzed. Methods: CivaSheet is designed as an array of directional palladium-103 sources (CivaDots). From the postoperative computed tomography (CT) scans of three patients, the shape of each implanted CivaSheet was reconstructed. In order to obtain a realistic estimate of the distribution of curvatures, the mean radius of curvature at the location of each CivaDot was calculated. A Monte Carlo simulation (FLUKA) of a single CivaDot was designed, based upon published geometry and material specifications. Both the radial dose function analog and the two-dimensional anisotropy function analog for the CivaDot were validated in comparison with film measurements and benchmarked to published Monte Carlo data. A value for the dose-rate constant Λ = 0.587(19) cGy/h/U for a CivaDot source in water was calculated as well. Knowledge of the dose distribution in the vicinity of each source allowed the dose at any point around CivaSheets of different curvatures and orientations to be calculated. Results: The local radius of curvature was found to be primarily between 2 and 8 cm in all three patient implants. On the unshielded side of an inward-facing curved CivaSheet implant of radius 2 cm, the calculated dose at 0.5 cm depth exceeded the prescribed dose by $ 20%, while on the shielded side the dose increased by a factor of two, thus compromising the shielding efficiency of the original design. On the unshielded side of an outward-facing curved implant, the dose at 0.5 cm depth decreased by $ 20%. Conclusions: When tumor bed curvature can be estimated from the preplanning CT scan, the results from this study provide quantitative guide for modifying the source strength to achieve the desired clinical results. In many intraoperative cases, however, accurate preplanning based on surface curvature may not be practical. In such situations, knowledge of the dosimetric impact of the surface curvature provides motivation for avoiding implantation geometries that can lead to either over/ underdosing the target, or excess dose to healthy tissue.

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Report of the First Patient Treated for Pelvic Sarcoma With a Directional 103Pd Brachytherapy Device

Castañeda

Khalili

Emrich

et al. 2020

Advances in Radiation Oncology

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Dosimetric characterization of a new directional low‐dose rate brachytherapy source

Cited by 8 publications

References 30 publications

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

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

Application of a directional palladium‐103 brachytherapy device on a curved surface

Report of the First Patient Treated for Pelvic Sarcoma With a Directional 103Pd Brachytherapy Device

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