Positioning reproducibility with and without rotational corrections for 2 head and neck immobilization systems

Courneyea, L.; Mullins, John P.; Howard, Michelle E.; Foote, Robert L.; Garces, Yolanda I.; Daniel, J.; Beltran, Chris; Brinkmann, Debra H.; Pafundi, Deanna H.

doi:10.1016/j.prro.2015.05.003

Cited by 5 publications

(12 citation statements)

References 17 publications

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“…It is unclear whether this was the result of the type of head support or other immobilization factors, since these also differed between cohorts. In contrast to others [2,6], we did not observe an improvement in intrafraction stabilization using an IHS compared to a SHS.…”

Section: Discussioncontrasting

confidence: 99%

“…Several studies investigating position verification in HNC used standard bony landmarks as match structures [3,6,17]. According to the ESTRO guideline it may be prudent to define primary match structures in close proximity to the target which will determine the position of the clipbox.…”

Section: Discussionmentioning

confidence: 99%

“…Currently, various individual head supports are commercially available. We selected the Klarity AccuCushion, for which previous studies reported to have found satisfactory results [5,6]. This type of IHS fully supports head, neck and shoulders and takes 10-15 min to prepare.…”

Section: Discussionmentioning

confidence: 99%

“…In head-and-neck radiotherapy, set-up errors during the course of treatment should be reduced to a minimum using adequate patient immobilization and correction of positioning errors. In attempts to reduce planning target volume (PTV) margins and prevent anatomic deformation, several small series have analysed set-up reproducibility by adding an individual head support (IHS) to the immobilization system [1][2][3][4][5][6][7][8][9][10][11]. Of these studies, five used cone-beam CT (CBCT) imaging with online correction protocols [1,4,5,10,11].…”

Section: Introductionmentioning

confidence: 99%

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The influence of a six degrees of freedom couch and an individual head support in patient positioning in radiotherapy of head and neck cancer

Rodrigues

Veen

Egmond

et al. 2019

Physics and Imaging in Radiation Oncology

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Reproducible patient positioning is important in radiotherapy (RT) of head-and-neck cancer. We therefore compared setup errors in head-and-neck RT resulting from three different patient positioning systems. Patients were either treated with a standard head support (SHS) and conventional treatment couch (SHS-3, n = 10), a SHS and rotational couch (SHS-6, n = 10), or an individual head support (IHS) and rotational couch (IHS-6, n = 10). Interfraction mean translation vector lenghts were significantly lower for IHS-6 compared to SHS-3 (0.8 ± 0.3 mm vs. 1.4 ± 0.7 mm, P = 0.001). Intrafraction displacement was comparable among cohorts. This study showed that the use of a six degrees of freedom couch combined with an IHS in head-and-neck RT resulted in better interfraction reproducibility.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The influence of a six degrees of freedom couch and an individual head support in patient positioning in radiotherapy of head and neck cancer

Rodrigues

Veen

Egmond

et al. 2019

Physics and Imaging in Radiation Oncology

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“…The typical H&N PTV margin of 5 mm assumes a high degree of reproducibility and stability, achievable only by a well-struck balance between patient immobilization and comfort. 12 Thermoplastic masks are conventionally used to immobilize the head, neck, and shoulders for H&N IMRT treatments. Such masks offer a reasonable amount of immobilization provided that any anatomical changes between simulation and treatment are minimal 13 ; however, these masks are not able to account for anatomical changes over time due to weight loss, nor are they always adequate for patient fixation in the cases of lordosis or scoliosis.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Efficacy of Rotational Corrections for Standard-Fractionation Head and Neck Image-Guided Radiotherapy

Kung

Tran

Poon

et al. 2019

Technol Cancer Res Treat

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Purpose: Modern linear accelerators are equipped with cone beam computed tomography and robotic couches that can correct for errors in the translational (X, Y, Z) and rotational (α, β, γ) axes prior to treatment delivery. Here, we compared the positional accuracy of 2 cone beam registration approaches: (1) employing translational shifts only in 3 degrees of freedom (X, Y, Z), versus; (2) using translational-rotational shifts in 6 degrees of freedom (X, Y, Z, α, β, γ). Methods: This retrospective study examined 140 interfraction cone beam images from 20 patients with head and neck cancer treated with standard intensity-modulated radiation therapy. The cone beam images were matched to planning simulation scans in 3, then in 6 degrees of freedom, using the mandible, clivus, and C2 and C7 vertebrae as surrogate volumes. Statistical analyses included a generalized mixed model and was used to assess whether there were significant differences in acceptable registrations between the 2 correction methods. Results: The rates of improvement with corrections in 6 degrees of freedom for the mandible with a 5-mm expansion margin were 54.55% ( P = .793), for the clivus 85.71% ( P = .222), and for C7 87.50% ( P = .015). There was a 100% increase in acceptability for the C2 vertebra within the 5-mm margin ( P < .001). For the 3-mm expansion margin, the rates of improvement for the mandible, clivus, C2, and C7 were 63.16% ( P = .070), 91.30% ( P = .011), 84.21% ( P = .027), and 76.92% ( P < .001), respectively. Conclusions: Significant registration improvements with the use of rotational corrections with a 5-mm expansion margin are only seen in the C7 vertebra. At the 3-mm margin, significant improvements are found for the C2, C7, and clivus registrations, suggesting that intensity-modulated radiotherapy treatments for head and neck cancers with 3-mm planning target volume margins may benefit from corrections in 6 degrees of freedom.

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Dosimetric effect of six degrees of freedom couch top with rotational setup error corrections in proton therapy

Katō

Sasaki

Kato

et al. 2023

J Applied Clin Med Phys

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PurposeTo investigate the dosimetric effect of six degrees of freedom (6DoF) couch top with rotational corrections in proton therapy (PT).MethodsThe water equivalent thickness (WET) was measured using a proton beam with a 6DoF couch top and patient immobilization base plate (PIBP) placed in front of a motorized water phantom. The accuracy verification was performed with the beam axis set perpendicular to the 6DoF couch top and tilted in 10° steps from 10° to 30°. Up to 3° rotational correction may be added during the actual treatment to correct the rotational setup error on our system. The measured and calculated values using the treatment planning system were compared. Additionally, the effect of the 3° difference was evaluated using actual measurements concerning each angle on the proton beam range.ResultsThe WET of the 6DoF couch top and PIBP were 8.5 ± 0.1 mm and 6.8 ± 0.1 mm, respectively. The calculation and the actual measurement at each angle agreed within 0.2 mm at the maximum. A maximum difference of approximately 0.6 mm was confirmed when tilted at 3° following 30° with the 6DoF couch top plus PIBP.ConclusionsThe dosimetric effect of the 6DoF couch top with rotational corrections in PT differs depending on the incidence angle on the couch top, and it increased with the increased oblique angle of incidence. However, the effect on the range was as small as 0.6 mm at the maximum. The amount of rotational correction, the angle of incidence of the beam, and the effect of rotational corrections on the proton beam range may differ depending on the structure of the couch top. Therefore, sufficient prior confirmation, and subsequent periodical quality assurance management are important.

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Positioning reproducibility with and without rotational corrections for 2 head and neck immobilization systems

Cited by 5 publications

References 17 publications

The influence of a six degrees of freedom couch and an individual head support in patient positioning in radiotherapy of head and neck cancer

The influence of a six degrees of freedom couch and an individual head support in patient positioning in radiotherapy of head and neck cancer

Evaluation of the Efficacy of Rotational Corrections for Standard-Fractionation Head and Neck Image-Guided Radiotherapy

Dosimetric effect of six degrees of freedom couch top with rotational setup error corrections in proton therapy

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