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adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure.Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.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 Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included.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

Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al. Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al.[64] Triangles indicate which parameter detected the displacement. Shaded regions indicate the period after the detection in which tissue monitoring was paused, a new template window was selected, and the TDPs were reset. The bottom graph shows the position of the external marker on the volunteer’s hip.
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FIG3: Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al. Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al.[64] Triangles indicate which parameter detected the displacement. Shaded regions indicate the period after the detection in which tissue monitoring was paused, a new template window was selected, and the TDPs were reset. The bottom graph shows the position of the external marker on the volunteer’s hip.

Mentions: To demonstrate early feasibility of 2D US in monitoring intrafractional soft-tissue displacements of the prostate, Schlosser, et al. [64] developed a method using two tissue displacement parameters (TDPs) derived from the normalized cross correlation similarity measure that characterized in-plane and out-of-plane displacement of the target volume in real time relative to a reference position. The method, used in conjunction with the robotic device described in Section 2.2.1, successfully detected prostate displacements in healthy human subjects before they exceeded 2.3, 2.5, and 2.8 mm in the AP, SI, and ML directions, respectively, at the 95% confidence level, with a total system latency averaging 173 ms. False positives did not exceed 1.5 events over 10 minutes of continuous imaging. The authors performed an online demonstration of the system in which a healthy human subject was asked to physically move his hips at certain time intervals, causing a displacement of the prostate relative to a “world” reference frame. Hip displacements were monitored using an external marker on the volunteer’s hip and with the 2D US-based TDPs. The TDPs detected 10 out of 10 prostate displacements and registered zero false positives over the 12-minute online test. Results of the test are illustrated in Figure 3.


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

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

Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al. Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al.[64] Triangles indicate which parameter detected the displacement. Shaded regions indicate the period after the detection in which tissue monitoring was paused, a new template window was selected, and the TDPs were reset. The bottom graph shows the position of the external marker on the volunteer’s hip.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

FIG3: Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al. Tissue displacement parameters (TDPs) during 12-min test session, reproduced from Schlosser et al.[64] Triangles indicate which parameter detected the displacement. Shaded regions indicate the period after the detection in which tissue monitoring was paused, a new template window was selected, and the TDPs were reset. The bottom graph shows the position of the external marker on the volunteer’s hip.
Mentions: To demonstrate early feasibility of 2D US in monitoring intrafractional soft-tissue displacements of the prostate, Schlosser, et al. [64] developed a method using two tissue displacement parameters (TDPs) derived from the normalized cross correlation similarity measure that characterized in-plane and out-of-plane displacement of the target volume in real time relative to a reference position. The method, used in conjunction with the robotic device described in Section 2.2.1, successfully detected prostate displacements in healthy human subjects before they exceeded 2.3, 2.5, and 2.8 mm in the AP, SI, and ML directions, respectively, at the 95% confidence level, with a total system latency averaging 173 ms. False positives did not exceed 1.5 events over 10 minutes of continuous imaging. The authors performed an online demonstration of the system in which a healthy human subject was asked to physically move his hips at certain time intervals, causing a displacement of the prostate relative to a “world” reference frame. Hip displacements were monitored using an external marker on the volunteer’s hip and with the 2D US-based TDPs. The TDPs detected 10 out of 10 prostate displacements and registered zero false positives over the 12-minute online test. Results of the test are illustrated in Figure 3.

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