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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adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure.Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.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 Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.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

Seven-beam treatment plan comparison, reproduced from Schlosser et al.Seven-beam treatment plan comparison, reproduced from Schlosser et al. [58] (a) Axial dose distribution for a clinical prostate IMRT plan. (b) Axial dose distribution for a reoptimized IMRT plan with restricted beam angles to avoid U.S. probe and robot links. (c) Dose-volume histograms for the clinical IMRT plan (circles), reoptimized plan (triangles), and reoptimized plan with reduced margin (squares). Note that the IMRT plan with reduced margins underdoses original planning target volume but maintains gross tumor volume coverage and improves healthy tissue sparing.
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FIG7: Seven-beam treatment plan comparison, reproduced from Schlosser et al.Seven-beam treatment plan comparison, reproduced from Schlosser et al. [58] (a) Axial dose distribution for a clinical prostate IMRT plan. (b) Axial dose distribution for a reoptimized IMRT plan with restricted beam angles to avoid U.S. probe and robot links. (c) Dose-volume histograms for the clinical IMRT plan (circles), reoptimized plan (triangles), and reoptimized plan with reduced margin (squares). Note that the IMRT plan with reduced margins underdoses original planning target volume but maintains gross tumor volume coverage and improves healthy tissue sparing.

Mentions: Several groups have investigated the feasibility of strategy (1) by studying whether constraints on beam angles imposed by intrafractional US image guidance hardware affect the quality of treatment. Wu, et al. [81] found that avoiding the anterior-posterior beam in radiation planning, which would pass through a US probe placed in the transabdominal imaging position, resulted in a negligible effect of the transducer on dosage delivered. Schlosser, et al. [58] conducted a second feasibility study that compared a seven-beam clinical plan for a prostate IMRT patient with a seven-beam plan for the same patient that excluded a 90 degree anterior sector in order to avoid US guidance hardware in the transabdominal imaging position. No impactful difference between the plans was found (Figure 7). These two studies show that beam avoidance of US image guidance hardware is a feasible option for delivering prostate radiotherapy guided by transabdominal US imaging.


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

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

Seven-beam treatment plan comparison, reproduced from Schlosser et al.Seven-beam treatment plan comparison, reproduced from Schlosser et al. [58] (a) Axial dose distribution for a clinical prostate IMRT plan. (b) Axial dose distribution for a reoptimized IMRT plan with restricted beam angles to avoid U.S. probe and robot links. (c) Dose-volume histograms for the clinical IMRT plan (circles), reoptimized plan (triangles), and reoptimized plan with reduced margin (squares). Note that the IMRT plan with reduced margins underdoses original planning target volume but maintains gross tumor volume coverage and improves healthy tissue sparing.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

FIG7: Seven-beam treatment plan comparison, reproduced from Schlosser et al.Seven-beam treatment plan comparison, reproduced from Schlosser et al. [58] (a) Axial dose distribution for a clinical prostate IMRT plan. (b) Axial dose distribution for a reoptimized IMRT plan with restricted beam angles to avoid U.S. probe and robot links. (c) Dose-volume histograms for the clinical IMRT plan (circles), reoptimized plan (triangles), and reoptimized plan with reduced margin (squares). Note that the IMRT plan with reduced margins underdoses original planning target volume but maintains gross tumor volume coverage and improves healthy tissue sparing.
Mentions: Several groups have investigated the feasibility of strategy (1) by studying whether constraints on beam angles imposed by intrafractional US image guidance hardware affect the quality of treatment. Wu, et al. [81] found that avoiding the anterior-posterior beam in radiation planning, which would pass through a US probe placed in the transabdominal imaging position, resulted in a negligible effect of the transducer on dosage delivered. Schlosser, et al. [58] conducted a second feasibility study that compared a seven-beam clinical plan for a prostate IMRT patient with a seven-beam plan for the same patient that excluded a 90 degree anterior sector in order to avoid US guidance hardware in the transabdominal imaging position. No impactful difference between the plans was found (Figure 7). These two studies show that beam avoidance of US image guidance hardware is a feasible option for delivering prostate radiotherapy guided by transabdominal US imaging.

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