Evaluation of Image-Guided Positioning for Frameless Intracranial Radiosurgery

Lamba, Michael; Breneman, John C.; Warnick, Ronald E.

doi:10.1016/j.ijrobp.2009.01.008

Cited by 60 publications

(47 citation statements)

References 16 publications

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“…In that report, intratreatment patient movement was assessed by comparing pre‐ and post‐treatment alignment. Differences of up to 1.0–1.2 mm were noted, with the greatest movement also in the longitudinal direction (9) . We speculate that the higher incidence of translational errors

< 1 mm

along the longitudinal axis could be attributed to the mask being less resistive in that direction.…”

Section: Discussionmentioning

confidence: 80%

“…The alignment accuracy of frame‐based radiosurgery of 0.3 mm to 1.5 mm is reported by several studies 9 , 23 , 25 . The AAPM Radiosurgery Task Group Report 54 states that the overall achievable positional uncertainty was 2.4 mm due to all error sources (22) .…”

Section: Discussionmentioning

confidence: 97%

“…The maximum residual setup error in the vertical direction was less than 0.9 mm. A previous study was conducted to examine patient stability during image‐guided frameless radiosurgery utilizing a thermoplastic mask similar to that used with our patients (9) . In that report, intratreatment patient movement was assessed by comparing pre‐ and post‐treatment alignment.…”

Section: Discussionmentioning

confidence: 99%

“…As a comparison, the positioning error associated with stereotactic frame system was 1.4 mm. Many studies have also investigated the positioning accuracy of using bite plate and image‐guided frameless radiosurgery systems and reported positioning setup errors ranging from 0.4 to 1.2 mm 9 , 11 , 12 , 15 , 26 …”

Section: Discussionmentioning

confidence: 99%

“…Avoiding use of a hard‐frame ring or a bite plate makes this system suitable for a wider variety of patients. Many studies have investigated the use of planar imaging systems to guide frameless SRS/FSRT treatments 9 , 13 , 15 . Several studies have shown that anatomical structures and soft tissues are better visualized on axial images of CBCT than planar images 14 , 16 , 18 .…”

Section: Introductionmentioning

confidence: 99%

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Six degrees of freedom CBCT‐based positioning for intracranial targets treated with frameless stereotactic radiosurgery

Dhabaan

Schreibmann

Siddiqi

et al. 2012

J Applied Clin Med Phys

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Frameless radiosurgery is an attractive alternative to the framed procedure if it can be performed with comparable precision in a reasonable time frame. Here, we present a positioning approach for frameless radiosurgery based on in‐room volumetric imaging coupled with an advanced six‐degrees‐of‐freedom (6 DOF) image registration technique which avoids use of a bite block. Patient motion is restricted with a custom thermoplastic mask. Accurate positioning is achieved by registering a cone‐beam CT to the planning CT scan and applying all translational and rotational shifts using a custom couch mount. System accuracy was initially verified on an anthropomorphic phantom. Isocenters of delineated targets in the phantom were computed and aligned by our system with an average accuracy of 0.2 mm, 0.3 mm, and 0.4 mm in the lateral, vertical, and longitudinal directions, respectively. The accuracy in the rotational directions was 0.1°, 0.2°, and 0.1° in the pitch, roll, and yaw, respectively. An additional test was performed using the phantom in which known shifts were introduced. Misalignments up to 10 mm and 3° in all directions/rotations were introduced in our phantom and recovered to an ideal alignment within 0.2 mm, 0.3 mm, and 0.4 mm in the lateral, vertical, and longitudinal directions, respectively, and within 0.3° in any rotational axis. These values are less than couch motion precision. Our first 28 patients with 38 targets treated over 63 fractions are analyzed in the patient positioning phase of the study. Mean error in the shifts predicted by the system were less than 0.5 mm in any translational direction and less than 0.3° in any rotation, as assessed by a confirmation CBCT scan. We conclude that accurate and efficient frameless radiosurgery positioning is achievable without the need for a bite block by using our 6 DOF registration method. This system is inexpensive compared to a couch‐based 6 DOF system, improves patient comfort compared to systems that utilize a bite block, and is ideal for the treatment of pediatric patients with or without general anesthesia, as well as of patients with dental issues. From this study, it is clear that only adjusting for 4 DOF may, in some cases, lead to significant compromise in PTV coverage. Since performing the additional match with 6 DOF in our registration system only adds a relatively short amount of time to the overall process, we advocate making the precise match in all cases.PACS number: 87.55.tm; 87.55.Qr; 87.57.nj

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< 1 mm

along the longitudinal axis could be attributed to the mask being less resistive in that direction.…”

Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Six degrees of freedom CBCT‐based positioning for intracranial targets treated with frameless stereotactic radiosurgery

Dhabaan

Schreibmann

Siddiqi

et al. 2012

J Applied Clin Med Phys

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Optimization of isocenter position for multiple targets with nonuniform‐margin expansion

Miao

Dai

2022

J Applied Clin Med Phys

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The single isocenter for multiple-target (SIMT) technique has become a popular treatment technique for multiple brain metastases. We have implemented a method to obtain a nonuniform margin for SIMT technique. In this study, we further propose a method to determine the isocenter position so that the total expanded margin volume is minimal. Materials and method:Based on a statistical model, the relationship between nonuniform margin and the distance d (from isocenter to target point), setup uncertainties, and significance level was established. Due to the existence of rotational error, there is a nonlinear relationship between the margin volume and the isocenter position. Using numerical simulation, we study the relationship between optimal isocenter position and translational error, rotational error, and target size. In order to find the optimal isocenter position quickly, adaptive simulated annealing (ASA) algorithm was used. This method was implemented in the Pinnacle 3 treatment planning system and compared with isocenter at center-ofgeometric (COG), center-of -volume (COV), and center-of -surface (COS). Ten patients with multiple brain metastasis targets treated with the SIMT technique was selected for evaluation. Results: When the size of tumors is equal, the optimal isocenter obtained by ASA and numerical simulation coincides with COG, COV, and COS. When the size of tumors is different, the optimal isocenter is close to the large tumor. The position of COS point is closer to the optimal point than the COV point for nearly all cases.Moreover,in some cases the COS point can be approximately selected as the optimal point. The ASA algorithm can reduce the calculating time from several hours to tens of seconds for three or more tumors. Using multiple brain metastases targets, a series of volume difference and calculating time were obtained for various tumor number, tumor size, and separation distances. Compared with the margin volume with isocenter at COG, the margin volume for optimal point can be reduced by up to 27.7%. Conclusion: Optimal treatment isocenter selection of multiple targets with large differences could reduce the total margin volume. ASA algorithm can significantly improve the speed of finding the optimal isocenter. This method can be used for clinical isocenter selection and is useful for the protection of normal tissue nearby.

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Novalis and Varian Systems

Rosen

Pino

2012

Stereotactic Body Radiation Therapy

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Evaluation of Image-Guided Positioning for Frameless Intracranial Radiosurgery

Cited by 60 publications

References 16 publications

Six degrees of freedom CBCT‐based positioning for intracranial targets treated with frameless stereotactic radiosurgery

Six degrees of freedom CBCT‐based positioning for intracranial targets treated with frameless stereotactic radiosurgery

Optimization of isocenter position for multiple targets with nonuniform‐margin expansion

Novalis and Varian Systems

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