Dosimetric consequences of misalignment and realignment in prostate 3DCRT using intramodality ultrasound image guidance

Fraser, Danielle; Chen, Yong; Poon, Emily; Cury, Fabio; Falco, Tony; Verhaegen, Frank

doi:10.1118/1.3429127

Cited by 17 publications

(16 citation statements)

References 30 publications

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“…Three-dimensional US imaging with external US transducers offers possibilities for noninvasive imageguided brachytherapy for prostate, cervix, and breast without geometric distortion, although these techniques are currently rarely used for brachytherapy. 176,177 However, none of these techniques can presently provide information on tissue heterogeneities as would be required within the scope of the current task group report. In US techniques, contrast-enhanced imaging 178 and tissue typing 179 are active fields of research, which may also play a future role in brachytherapy.…”

Section: Iva6 Other Imaging Modalitiesmentioning

confidence: 99%

Report of the Task Group 186 on model‐based dose calculation methods in brachytherapy beyond the TG‐43 formalism: Current status and recommendations for clinical implementation

et al. 2012

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The charge of Task Group 186 (TG-186) is to provide guidance for early adopters of model-based dose calculation algorithms (MBDCAs) for brachytherapy (BT) dose calculations to ensure practice uniformity. Contrary to external beam radiotherapy, heterogeneity correction algorithms have only recently been made available to the BT community. Yet, BT dose calculation accuracy is highly dependent on scatter conditions and photoelectric effect cross-sections relative to water. In specific situations, differences between the current water-based BT dose calculation formalism (TG-43) and MBDCAs can lead to differences in calculated doses exceeding a factor of 10. MBDCAs raise three major issues that are not addressed by current guidance documents: (1) MBDCA calculated doses are sensitive to the dose specification medium, resulting in energy-dependent differences between dose calculated to water in a homogeneous water geometry (TG-43), dose calculated to the local medium in the heterogeneous medium, and the intermediate scenario of dose calculated to a small volume of water in the heterogeneous medium. (2) MBDCA doses are sensitive to voxel-by-voxel interaction cross sections. Neither conventional single-energy CT nor ICRU∕ICRP tissue composition compilations provide useful guidance for the task of assigning interaction cross sections to each voxel. (3) Since each patient-source-applicator combination is unique, having reference data for each possible combination to benchmark MBDCAs is an impractical strategy. Hence, a new commissioning process is required. TG-186 addresses in detail the above issues through the literature review and provides explicit recommendations based on the current state of knowledge. TG-43-based dose prescription and dose calculation remain in effect, with MBDCA dose reporting performed in parallel when available. In using MBDCAs, it is recommended that the radiation transport should be performed in the heterogeneous medium and, at minimum, the dose to the local medium be reported along with the TG-43 calculated doses. Assignments of voxel-by-voxel cross sections represent a particular challenge. Electron density information is readily extracted from CT imaging, but cannot be used to distinguish between different materials having the same density. Therefore, a recommendation is made to use a number of standardized materials to maintain uniformity across institutions. Sensitivity analysis shows that this recommendation offers increased accuracy over TG-43. MBDCA commissioning will share commonalities with current TG-43-based systems, but in addition there will be algorithm-specific tasks. Two levels of commissioning are recommended: reproducing TG-43 dose parameters and testing the advanced capabilities of MBDCAs. For validation of heterogeneity and scatter conditions, MBDCAs should mimic the 3D dose distributions from reference virtual geometries. Potential changes in BT dose prescriptions and MBDCA limitations are discussed. When data required for full MBDCA implementation are insufficient, interim ...

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Section: Iva6 Other Imaging Modalitiesmentioning

confidence: 99%

Report of the Task Group 186 on model‐based dose calculation methods in brachytherapy beyond the TG‐43 formalism: Current status and recommendations for clinical implementation

et al. 2012

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“…14) or ultrasound prostate localization instead of FM for prostate localization at the EBRT stage. 15 The use of CBCT could also potentially permit the implantation of FM of smaller dimensions, which would reduce the size of the dose shadows.…”

Section: Ivb Clinical Casesmentioning

confidence: 99%

Dose reduction in LDR brachytherapy by implanted prostate gold fiducial markers

et al. 2012

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“…CT images are also acquired at simulation therefore enabling calculation of the true delivered fractional dose in conjunction with a treatment planning system. 7 In this work two probes were used to acquire US image data. All phantom data were acquired using a linear US probe provided with the system (linear probe: type L14-5/38, center frequency 7.2 MHz, Sonix Series, Ultrasonix Medical Corporation, Richmond, BC, Canada) and patient data were acquired using the linear probe and a curvilinear probe (curvilinear probe: type C5-2/60, center frequency 3.5 MHz, Sonix Series, Ultrasonix Medical Corporation, Richmond, BC, Canada).…”

Section: Iia Clarity Tm 3dus Systemmentioning

confidence: 99%

“…Ultrasound (US) imaging is an important cross-sectional imaging modality in diagnostic radiology and is proving to be a useful quantitative tool also in the field of radiotherapy treatment verification. [1][2][3][4][5][6][7][8][9] Organ motion and changes in shape and volume, and setup errors are issues of increasing importance for intensity modulated radiation therapy (IMRT) treatments. [10][11][12] Accurate patient positioning is now a major requirement, as shown by the increasing interest in image guided radiation therapy (IGRT).…”

Section: Introductionmentioning

confidence: 99%

A CT based correction method for speed of sound aberration for ultrasound based image guided radiotherapy

et al. 2011

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Dosimetric consequences of misalignment and realignment in prostate 3DCRT using intramodality ultrasound image guidance

Cited by 17 publications

References 30 publications

Report of the Task Group 186 on model‐based dose calculation methods in brachytherapy beyond the TG‐43 formalism: Current status and recommendations for clinical implementation

Report of the Task Group 186 on model‐based dose calculation methods in brachytherapy beyond the TG‐43 formalism: Current status and recommendations for clinical implementation

Dose reduction in LDR brachytherapy by implanted prostate gold fiducial markers

A CT based correction method for speed of sound aberration for ultrasound based image guided radiotherapy

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