Direction-Modulated Brachytherapy for High-Dose-Rate Treatment of Cervical Cancer. I: Theoretical Design

Han, Dan; Webster, Matthew J.; Scanderbeg, Daniel J.; Yashar, Catheryn M.; Choi, Du Young; Song, Byung Cheol; Dević, Slobodan; Ravi, Ananth; Song, William Y.

doi:10.1016/j.ijrobp.2014.02.039

Cited by 38 publications

(57 citation statements)

References 26 publications

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“…The total DMBT tandem thickness (6 mm) remained similar to the conventional tandem applicators (3–6.6 mm), allowing compatibility with ring/ovoid, cylinder, and other applicators. As the 192 Ir source in the DMBT tandem is situated 2.05 mm away from the shield center, and the TF at 1 cm (5 cm) distance is <16% (<37%) compared to the conventional tandem (100%), it gives rise to a higher degree of freedom in intensity modulation making it suitable for treating larger (more irregularly shaped) CTV HR …”

Section: Discussionmentioning

confidence: 99%

“…All cases were then reoptimized for both Con.T&R and DMBT&R to receive the same CTV HR D 90 . In total, 108 individual plans (8 shields × 12 clinical cases) with DMBT&R and 12 respective individual Con.T&R plans were re‐optimized with an in‐house code based on gradient projection convex optimization algorithm. The optimization process was previously described in detail .…”

Section: Methodsmentioning

confidence: 99%

“…Such would be helpful especially when the CTV HR is irregular/bulky in shape and extends beyond upper vagina away from the reaches of the ovoids/ring. Recognizing this apparent lag in tandem technology, a novel six‐channel MR‐compatible intrauterine tandem applicator is designed around an isotropic 192 Ir source based on the concept of direction modulated brachytherapy (DMBT) . This design is able to create directional radiation dose profile via intelligently designed tungsten shield leading to enhanced dose sculpting capacity for each individual CTV HR through inverse optimization.…”

Section: Introductionmentioning

confidence: 99%

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Direction modulated brachytherapy (DMBT) tandem applicator for cervical cancer treatment: Choosing the optimal shielding material

et al. 2018

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direction modulated brachytherapy (DMBT) tandem applicator for cervical cancer treatment: Choosing the optimal shielding material

et al. 2018

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“…High-dose-rate (HDR) sources containing 153 Gd (9) or 192 Ir (10,11) with built-in shielding have been investigated, but current technology prohibits interstitial implantation due to the required shield thickness and resultant puncture diameter. A directional source is more readily achieved with a source having lower energy emissions and consequently a thinner shield.…”

Section: Introductionmentioning

confidence: 99%

A directional 103Pd brachytherapy device: Dosimetric characterization and practical aspects for clinical use

Rivard

2017

Brachytherapy

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PURPOSE A brachytherapy device has been developed with shielding to provide directional brachytherapy for preferentially irradiating malignancies while sparing healthy tissues. The CivaSheet is a flexible low-dose-rate brachytherapy device containing CivaDots with 103Pd shielded by a thin Au disk. This is the first report of a clinical dosimetric characterization of the CivaSheet device. METHODS AND MATERIALS Radiation dose distributions near a CivaDot were estimated using the MCNP6 radiation transport code. CivaSheet arrays were also modeled to evaluate the dose superposition principle for treatment planning. The resultant data were commissioned in a treatment planning system (VariSeed 9.0) and the accuracy of the dose superposition principle was evaluated for summing individual elements comprising a planar CivaSheet. RESULTS The dose-rate-constant (0.579 cGy/h/U) was lower than for 103Pd seeds due to Au L-shell x-rays increasing the air-kerma strength. Radial dose function values at 0.1, 0.5, 2, 5, and 10 cm were 1.884, 1.344, 0.558, 0.088, and 0.0046. The 2D anisotropy function exhibited dramatic reduction between the forward (0°) and rearward (180°) directions by a factor of 276 at r=0.1 cm, 24 at r=1 cm, and 5.3 at r=10 cm. This effect diminished due to increasingly scattered radiation. The largest gradient in the 2D anisotropy function was in contact with the device at 92° due to the Au disk shielding. TPS commissioning and dose superposition accuracies were typically within 2%. CONCLUSIONS Simulations of the CivaDot yielded comprehensive dosimetry parameters that were entered into a TPS and deemed acceptable for clinical use. Dosimetry measurements of the CivaSheet are also of interest to the brachytherapy community.

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“…Emerging technologies, including static adjustable shielding and dynamic modulated BT with rotating paddle, can achieve highly conformal dose distributions in large targets of complex shapes. 35-37 However, when used in pure IC BT, directional modulation of intensity may lead to excessively high doses near the applicator along the emission window axis 36 . These techniques need to stand the test of further studies before their routine implementation.…”

Section: Discussionmentioning

confidence: 99%

Virtual modelling of novel applicator prototypes for cervical cancer brachytherapy

Petrič

Hudej

Al-Hammadi

et al. 2016

Radiology and Oncology

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BackgroundStandard applicators for cervical cancer Brachytherapy (BT) do not always achieve acceptable balance between target volume and normal tissue irradiation. We aimed to develop an innovative method of Target-volume Density Mapping (TDM) for modelling of novel applicator prototypes with optimal coverage characteristics. Patients and methods. Development of Contour-Analysis Tool 2 (CAT-2) software for TDM generation was the core priority of our task group. Main requests regarding software functionalities were formulated and guided the coding process. Software validation and accuracy check was performed using phantom objects. Concepts and terms for standardized workflow of TDM post-processing and applicator development were introduced.ResultsCAT-2 enables applicator-based co-registration of Digital Imaging and Communications in Medicine (DICOM) structures from a sample of cases, generating a TDM with pooled contours in applicator-eye-view. Each TDM voxel is assigned a value, corresponding to the number of target contours encompassing that voxel. Values are converted to grey levels and transformed to DICOM image, which is transported to the treatment planning system. Iso-density contours (IDC) are generated as lines, connecting voxels with same grey levels. Residual Volume at Risk (RVR) is created for each IDC as potential volume that could contain organs at risk. Finally, standard and prototype applicators are applied on the TDM and virtual dose planning is performed. Dose volume histogram (DVH) parameters are recorded for individual IDC and RVR delineations and characteristic curves generated. Optimal applicator configuration is determined in an iterative manner based on comparison of characteristic curves, virtual implant complexities and isodose distributions.ConclusionsUsing the TDM approach, virtual applicator prototypes capable of conformal coverage of any target volume, can be modelled. Further systematic assessment, including studies on clinical feasibility, safety and effectiveness are needed before routine use of novel prototypes can be considered.

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Direction-Modulated Brachytherapy for High-Dose-Rate Treatment of Cervical Cancer. I: Theoretical Design

Cited by 38 publications

References 26 publications

Direction modulated brachytherapy (DMBT) tandem applicator for cervical cancer treatment: Choosing the optimal shielding material

Direction modulated brachytherapy (DMBT) tandem applicator for cervical cancer treatment: Choosing the optimal shielding material

A directional 103Pd brachytherapy device: Dosimetric characterization and practical aspects for clinical use

Virtual modelling of novel applicator prototypes for cervical cancer brachytherapy

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