Repositioning Accuracy with the Laitinen Frame for Fractionated Stereotactic Radiation Therapy in Adult and Pediatric Brain Tumors: Preliminary Report

Kalapurakal, John A.; Ilahi, Zainab; Kepka, A.; Bista, Tomasz; Goldman, Stewart; Tomita, Tadanori; Marymont, Maryanne Hoffman

doi:10.1148/radiology.218.1.r01ja23157

Cited by 20 publications

(9 citation statements)

References 24 publications

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“…In particular, the accuracy of the Laitinen frame, 22 used for stereotactic radiotherapy treatment, was tested by several authors using CT or portal images of phantom and/or patients. Ashamalla et al 25 showed a three-dimensional relocation accuracy ͑mean distance variation͒ of 1,5 mm±0,8 mm on a phantom while Kalapurakal et al 26 reported variations of 1,0 mm±0,7 mm; 0,8 mm±0,8 mm; 1,7 mm±1 mm, respectively, along x, y and z directions when testing the system on patients. Finally, Miranpuri et al, 27 using repeated CT images of a phantom, reported a mean error of about 2 mm along the z direction.…”

Section: Discussionmentioning

confidence: 99%

A simple device for high‐precision head image registration: Preliminary performance and accuracy tests

Pallotta

2007

Medical Physics

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The purpose of this paper is to present a new device for multimodal head study registration and to examine its performance in preliminary tests. The device consists of a system of eight markers fixed to mobile carbon pipes and bars which can be easily mounted on the patient's head using the ear canals and the nasal bridge. Four graduated scales fixed to the rigid support allow examiners to find the same device position on the patient's head during different acquisitions. The markers can be filled with appropriate substances for visualisation in computed tomography (CT), magnetic resonance, single photon emission computer tomography (SPECT) and positron emission tomography images. The device's rigidity and its position reproducibility were measured in 15 repeated CT acquisitions of the Alderson Rando anthropomorphic phantom and in two SPECT studies of a patient. The proposed system displays good rigidity and reproducibility characteristics. A relocation accuracy of less than 1,5 mm was found in more than 90% of the results. The registration parameters obtained using such a device were compared to those obtained using fiducial markers fixed on phantom and patient heads, resulting in differences of less than 1 degree and 1 mm for rotation and translation parameters, respectively. Residual differences between fiducial marker coordinates in reference and in registered studies were less than 1 mm in more than 90% of the results, proving that the device performed as accurately as noninvasive stereotactic devices. Finally, an example of multimodal employment of the proposed device is reported.

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Section: Discussionmentioning

confidence: 99%

A simple device for high‐precision head image registration: Preliminary performance and accuracy tests

Pallotta

2007

Medical Physics

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“…Various noninvasive frameless SRS systems have been evaluated. For example, a noninvasive frame (Laitinen frame) made of reinforced plastic and aluminum that is mounted into the patient's head by means of two earplugs and a nasal support has been used and its accuracy has been evaluated (3) . While this system was used for both children and adults, it still produced some discomfort, or pain in the ear and nose during treatments.…”

Section: Introductionmentioning

confidence: 99%

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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“…The aim of this work is, differently from more common in vivo CT, 1-6 cone beam CT, 7,8 portal, [9][10][11] and kV ͑Refs. 12 and 13͒ imaging studies, the evaluation with anthropomorphic phantom of the isocenter repositioning error during the several treatment sessions in stereotactic radiotherapy ͑SRT͒, measuring this quantity through comparisons between calculated dose distributions and corresponding film blackening maps.…”

Section: Introductionmentioning

confidence: 99%

Fractionated stereotactic radiotherapy: A method to evaluate geometric and dosimetric uncertainties using radiochromic films

et al. 2009

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In the authors' hospital, stereotactic radiotherapy treatments are performed with a Varian Clinac 600C equipped with a BrainLAB m3 micro-multileaf-collimator generally using the dynamic conformal arc technique. Patient immobilization during the treatment is achieved with a fixation mask supplied by BrainLAB, made with two reinforced thermoplastic sheets fitting the patient's head. With this work the authors propose a method to evaluate treatment geometric accuracy and, consequently, to determine the amount of the margin to keep in the CTV-PTV expansion during the treatment planning. The reproducibility of the isocenter position was tested by simulating a complete treatment on the anthropomorphic phantom Alderson Rando, inserting in between two phantom slices a high sensitivity Gafchromic EBT film, properly prepared and calibrated, and repeating several treatment sessions, each time removing the fixing mask and replacing the film inside the phantom. The comparison between the dose distributions measured on films and computed by TPS, after a precise image registration procedure performed by a commercial piece of software (FILMQA, 3cognition LLC (Division of ISP), Wayne, NJ), allowed the authors to measure the repositioning errors, obtaining about 0.5 mm in case of central spherical PTV and about 1.5 mm in case of peripheral irregular PTV. Moreover, an evaluation of the errors in the registration procedure was performed, giving negligible values with respect to the quantities to be measured. The above intrinsic two-dimensional estimate of treatment accuracy has to be increased for the error in the third dimension, but the 2 mm margin the authors generally use for the CTV-PTV expansion seems adequate anyway. Using the same EBT films, a dosimetric verification of the treatment planning system was done. Measured dose values are larger or smaller than the nominal ones depending on geometric irradiation conditions, but, in the authors' experimental conditions, always within 4%.

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Repositioning Accuracy with the Laitinen Frame for Fractionated Stereotactic Radiation Therapy in Adult and Pediatric Brain Tumors: Preliminary Report

Abstract: The Laitinen stereotactic localizer is well tolerated with accurate reproducibility during stereotactic radiation therapy. Preliminary local control rates are consistent with those in other reports.

Cited by 20 publications

References 24 publications

A simple device for high‐precision head image registration: Preliminary performance and accuracy tests

A simple device for high‐precision head image registration: Preliminary performance and accuracy tests

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

Fractionated stereotactic radiotherapy: A method to evaluate geometric and dosimetric uncertainties using radiochromic films

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