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Ultrasound Imaging in Radiation Therapy: From Interfractional to Intrafractional Guidance.

Western C, Hristov D, Schlosser J - Cureus (2015)

Bottom Line: With the proliferation of hypofractionated radiotherapy treatment regimens, such as stereotactic body radiation therapy (SBRT), interfractional and intrafractional imaging technologies are becoming increasingly critical to ensure safe and effective treatment delivery.Interfractional US guidance systems have been commercially adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure.Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, Stanford University.

ABSTRACT
External beam radiation therapy (EBRT) is included in the treatment regimen of the majority of cancer patients. With the proliferation of hypofractionated radiotherapy treatment regimens, such as stereotactic body radiation therapy (SBRT), interfractional and intrafractional imaging technologies are becoming increasingly critical to ensure safe and effective treatment delivery. Ultrasound (US)-based image guidance systems offer real-time, markerless, volumetric imaging with excellent soft tissue contrast, overcoming the limitations of traditional X-ray or computed tomography (CT)-based guidance for abdominal and pelvic cancer sites, such as the liver and prostate. Interfractional US guidance systems have been commercially adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure. More recently, several research groups have introduced concepts for intrafractional US guidance systems leveraging robotic probe placement technology and real-time soft tissue tracking software. This paper reviews various commercial and research-level US guidance systems used in radiation therapy, with an emphasis on hardware and software technologies that enable the deployment of US imaging within the radiotherapy environment and workflow. Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.

No MeSH data available.


Related in: MedlinePlus

Devices to support intrafractional US imaging.(a) Clarity Autoscan system, reproduced from Lachaine and Falco[47]. (b) Stanford prostate imaging robot, reproduced from Schlosser et al.[58] (c) University of Lubeck robot, adapted from Kuhlemann[59]. (d) Johns Hopkins robot, adapted from Sen et al.[61] (e) Stanford abdominal imaging robot.
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FIG2: Devices to support intrafractional US imaging.(a) Clarity Autoscan system, reproduced from Lachaine and Falco[47]. (b) Stanford prostate imaging robot, reproduced from Schlosser et al.[58] (c) University of Lubeck robot, adapted from Kuhlemann[59]. (d) Johns Hopkins robot, adapted from Sen et al.[61] (e) Stanford abdominal imaging robot.

Mentions: The first US guidance system capable of intrafractional imaging was the Clarity Autoscan System (Elekta AB, Stockholm, Sweden), shown in Figure 2A. The Clarity Autoscan builds upon the original Clarity System (Section 1.2) by replacing the 2D US imaging system with a mechanical “wobbler” 3D/4D US imaging system (refer to Section 4.1) and adding a hardware fixture for hands-free transperineal prostate imaging. The hardware device is a simple, manually-operated 5-degree of freedom (DOF) fixture that is mounted to a plate on the treatment couch between the patient’s legs. The sonographer uses the fixture to lock the US probe into position after the initial transperineal imaging position is found, thus freeing the sonographer to exit the treatment room and deliver radiotherapy while the US probe remains in imaging position. The 3D/4D probe enables volumetric US images to be automatically captured without physically moving the US probe head. The transperineal imaging setup is advantageous because the geometry of the fixture and probe keeps all system hardware out of the normal delivery plane for C-arm LINACs, therefore avoiding guidance system hardware interference with the radiation treatment process and enabling simultaneous US/CT imaging during the radiotherapy planning phase. Clinical studies of the system are underway to characterize the performance of the Clarity Autoscan for intrafractional monitoring.


Ultrasound Imaging in Radiation Therapy: From Interfractional to Intrafractional Guidance.

Western C, Hristov D, Schlosser J - Cureus (2015)

Devices to support intrafractional US imaging.(a) Clarity Autoscan system, reproduced from Lachaine and Falco[47]. (b) Stanford prostate imaging robot, reproduced from Schlosser et al.[58] (c) University of Lubeck robot, adapted from Kuhlemann[59]. (d) Johns Hopkins robot, adapted from Sen et al.[61] (e) Stanford abdominal imaging robot.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494460&req=5

FIG2: Devices to support intrafractional US imaging.(a) Clarity Autoscan system, reproduced from Lachaine and Falco[47]. (b) Stanford prostate imaging robot, reproduced from Schlosser et al.[58] (c) University of Lubeck robot, adapted from Kuhlemann[59]. (d) Johns Hopkins robot, adapted from Sen et al.[61] (e) Stanford abdominal imaging robot.
Mentions: The first US guidance system capable of intrafractional imaging was the Clarity Autoscan System (Elekta AB, Stockholm, Sweden), shown in Figure 2A. The Clarity Autoscan builds upon the original Clarity System (Section 1.2) by replacing the 2D US imaging system with a mechanical “wobbler” 3D/4D US imaging system (refer to Section 4.1) and adding a hardware fixture for hands-free transperineal prostate imaging. The hardware device is a simple, manually-operated 5-degree of freedom (DOF) fixture that is mounted to a plate on the treatment couch between the patient’s legs. The sonographer uses the fixture to lock the US probe into position after the initial transperineal imaging position is found, thus freeing the sonographer to exit the treatment room and deliver radiotherapy while the US probe remains in imaging position. The 3D/4D probe enables volumetric US images to be automatically captured without physically moving the US probe head. The transperineal imaging setup is advantageous because the geometry of the fixture and probe keeps all system hardware out of the normal delivery plane for C-arm LINACs, therefore avoiding guidance system hardware interference with the radiation treatment process and enabling simultaneous US/CT imaging during the radiotherapy planning phase. Clinical studies of the system are underway to characterize the performance of the Clarity Autoscan for intrafractional monitoring.

Bottom Line: With the proliferation of hypofractionated radiotherapy treatment regimens, such as stereotactic body radiation therapy (SBRT), interfractional and intrafractional imaging technologies are becoming increasingly critical to ensure safe and effective treatment delivery.Interfractional US guidance systems have been commercially adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure.Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, Stanford University.

ABSTRACT
External beam radiation therapy (EBRT) is included in the treatment regimen of the majority of cancer patients. With the proliferation of hypofractionated radiotherapy treatment regimens, such as stereotactic body radiation therapy (SBRT), interfractional and intrafractional imaging technologies are becoming increasingly critical to ensure safe and effective treatment delivery. Ultrasound (US)-based image guidance systems offer real-time, markerless, volumetric imaging with excellent soft tissue contrast, overcoming the limitations of traditional X-ray or computed tomography (CT)-based guidance for abdominal and pelvic cancer sites, such as the liver and prostate. Interfractional US guidance systems have been commercially adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure. More recently, several research groups have introduced concepts for intrafractional US guidance systems leveraging robotic probe placement technology and real-time soft tissue tracking software. This paper reviews various commercial and research-level US guidance systems used in radiation therapy, with an emphasis on hardware and software technologies that enable the deployment of US imaging within the radiotherapy environment and workflow. Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.

No MeSH data available.


Related in: MedlinePlus