Immobilization devices for intensity-modulated radiation therapy (IMRT)

Saw, Cheng B.; Yakoob, Richard; Enke, Charles Arthur; Lau, T.; Ayyangar, Komanduri M.

doi:10.1016/s0958-3947(00)00059-5

Cited by 37 publications

(28 citation statements)

References 52 publications

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“…Compared to stereotactic head frame systems, frameless systems have the advantage of improved patient safety and comfort, with more convenient clinical and technical workflow. The inter‐ and intrafractional setup errors for head and neck patients immobilized with thermoplastic masks have been extensively investigated 5 , 9 , 10 . Other immobilization devices, such as customizable head cushions and mouth pieces, can be coupled to the thermoplastic mask to further restrict patient motion (5) …”

Section: Introductionmentioning

confidence: 99%

Improved setup and positioning accuracy using a three‐point customized cushion/mask/bite‐block immobilization system for stereotactic reirradiation of head and neck cancer

Wang

Tung

et al. 2016

J Applied Clin Med Phys

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The purpose of this study was to investigate the setup and positioning uncertainty of a custom cushion/mask/bite‐block (CMB) immobilization system and determine PTV margin for image‐guided head and neck stereotactic ablative radiotherapy (HN‐SABR). We analyzed 105 treatment sessions among 21 patients treated with HN‐SABR for recurrent head and neck cancers using a custom CMB immobilization system. Initial patient setup was performed using the ExacTrac infrared (IR) tracking system and initial setup errors were based on comparison of ExacTrac IR tracking system to corrected online ExacTrac X‐rays images registered to treatment plans. Residual setup errors were determined using repeat verification X‐ray. The online ExacTrac corrections were compared to cone‐beam CT (CBCT) before treatment to assess agreement. Intrafractional positioning errors were determined using prebeam X‐rays. The systematic and random errors were analyzed. The initial translational setup errors were −0.8±1.3 mm, −0.8±1.6 mm, and 0.3±1.9 mm in AP, CC, and LR directions, respectively, with a three‐dimensional (3D) vector of 2.7±1.4 mm. The initial rotational errors were up to 2.4° if 6D couch is not available. CBCT agreed with ExacTrac X‐ray images to within 2 mm and 2.5°. The intrafractional uncertainties were 0.1±0.6 mm, 0.1±0.6 mm, and 0.2±0.5 mm in AP, CC, and LR directions, respectively, and 0.0∘±0.5°, 0.0∘±0.6°, and −0.1∘±0.4∘ in yaw, roll, and pitch direction, respectively. The translational vector was 0.9±0.6 mm. The calculated PTV margins normalmPTVfalse(90,95false) were within 1.6 mm when using image guidance for online setup correction. The use of image guidance for online setup correction, in combination with our customized CMB device, highly restricted target motion during treatments and provided robust immobilization to ensure minimum dose of 95% to target volume with 2.0 mm PTV margin for HN‐SABR.PACS number(s): 87.55.ne

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Section: Introductionmentioning

confidence: 99%

Improved setup and positioning accuracy using a three‐point customized cushion/mask/bite‐block immobilization system for stereotactic reirradiation of head and neck cancer

Wang

Tung

et al. 2016

J Applied Clin Med Phys

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“…It seems that these results can be cause according to the difference materials and production of the immobilization, and also lead the setup error during the CT-simulation and/or treatment. 21) In general, the pelvic immobilization devices are generally divided into a single anatomical region (i.e., the leg, pelvic, and etc.) or a bundle (i.e., the both leg and pelvis).…”

Section: Discussionmentioning

confidence: 99%

Comparison of Two Different Immobilization Devices for Pelvic Region Radiotherapy in Tomotherapy

Kim¹,

Jung

Cho³

et al. 2016

Prog Med Phys

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The purpose of this study was to compare the patient setup errors of two different immobilization devices (Feet Fix: FF and Leg Fix: LF) for pelvic region radiotherapy in Tomotherapy. Thirty six-patients previously treated with IMRT technique were selected, and divided into two groups based on applied immobilization devices (FF versus LF). We performed a retrospective clinical analysis including the mean, systematic, random variation, 3D-error, and calculated the planning target volume (PTV) margin. In addition, a rotational error (angles, o ) for each patient was analyzed using the automatic image registration. The 3D-errors for the FF and the LF groups were 3.70 mm and 4.26 mm, respectively; the LF group value was 15.1% higher than in the FF group. The treatment margin in the ML, SI, and AP directions were 5.23 mm (6.08 mm), 4.64 mm (6.29 mm), 5.83 mm (8.69 mm) in the FF group (and the LF group), respectively, that the FF group was lower than in the LF group. The percentage in treatment fractions for the FF group (ant the LF group) in greater than 5 mm at ML, SI, and AP direction was 1.7% (3.6%), 3.3% (10.7%), and 5.0% (16.1%), respectively. Two different immobilization devices were affected the patient setup errors due to different fixed location in low extremity. The radiotherapy for the pelvic region by Tomotherapy should be considering variation for the rotational angles including Yaw and Pitch direction that incorrect setup error during the treatment. In addition the choice of an appropriate immobilization device is important because an unalterable rotation angle affects the setup error.

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“…This is particularly important for patients with tumors adjacent to important normal intracranial and head-and-neck structures. For these patients, various immobilizers are used, and many studies have examined techniques to minimize geometrical discrepancies [1][2][3][4][5][6]. Bentel et al [1] describe a customized headrest to support the posterior head and neck.…”

Section: Related Studiesmentioning

confidence: 99%

Shape memory alloy (SMA)-based head and neck immobilizer for radiotherapy

Lee

Kim

Park

et al. 2015

Journal of Computational Design and Engineering

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Head-and-neck cancer is often treated with intensive irradiation focused on the tumor, while delivering the minimum amount of irradiation to normal cells. Since a course of radiotherapy can take 5-6 weeks or more, the repeatability of the patient posture and the fastening method during treatment are important determinants of the success of radiotherapy. Many devices have been developed to minimize positional discrepancies, but all of the commercial devices used in clinical practice are operated manually and require customized fixtures for each patient. This is inefficient and the performance of the fixture device depends on the operator's skill. Therefore, this study developed an automated head-and-neck immobilizer that can be used during radiotherapy and evaluated the positioning reproducibility in a phantom experiment. To eliminate interference caused by the magnetic field from computed tomography hardware, Ni À Ti shape-memory alloy wires were used as the actuating elements of the fixtures. The resulting positional discrepancy was less than 5 mm for all positions, which is acceptable for radiotherapy. & 2015 Society of CAD/CAM Engineers. Production and hosting by Elsevier. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Immobilization devices for intensity-modulated radiation therapy (IMRT)

Cited by 37 publications

References 52 publications

Improved setup and positioning accuracy using a three‐point customized cushion/mask/bite‐block immobilization system for stereotactic reirradiation of head and neck cancer

Improved setup and positioning accuracy using a three‐point customized cushion/mask/bite‐block immobilization system for stereotactic reirradiation of head and neck cancer

Comparison of Two Different Immobilization Devices for Pelvic Region Radiotherapy in Tomotherapy

Shape memory alloy (SMA)-based head and neck immobilizer for radiotherapy

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