Reducing the dosimetric impact of positional errors in field junctions for craniospinal irradiation using VMAT

Strojnik, A.; Méndez, Ignasi; Peterlin, Primož

doi:10.1016/j.rpor.2016.03.002

Cited by 22 publications

(26 citation statements)

References 27 publications

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“…For a 5-cm gradient length, 0.5-and 1.0-cm setup errors resulted in dose deviations of 10 and 20%, respectively [24,25]. For a 10-cm gradient length, 0.5-and 1.0-cm setup errors resulted in dose deviations of 5 and 10%, respectively [26][27][28]. Our data were perfectly consistent with these results.…”

Section: Discussionsupporting

confidence: 87%

Feasibility of hybrid TomoHelical- and TomoDirect-based volumetric gradient matching technique for total body irradiation

Hong

Kim

et al. 2019

Radiat Oncol

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Background: Tomotherapy-based total body irradiation (TBI) is performed using the headfirst position (HFP) and feet-first position (FFP) due to treatment length exceeding the 135 cm limit. To reduce the dosimetric variation at the match lines, we propose and verify a volumetric gradient matching technique (VGMT) by combining TomoHelical (TH) and TomoDirect (TD) modes. Methods: Two planning CT image sets were acquired with HFP and FFP using 15 × 55 × 18 cm 3 of solid water phantom. Planning target volume (PTV) was divided into upper, lower, and gradient volumes. The junction comprised 2-cm thick five and seven gradient volumes (5-GVs and 7-GVs) to create a dose distribution with a gentle slope. TH-IMRT and TD-IMRT plans were generated with 5-GVs and 7-GVs. The setup error in the calculated dose was assessed by shifting dose distribution of the FFP plan by 5, 10, 15, and 20 mm in the longitudinal direction and comparing it with the original. Doses for 95% (D95) and 5% of the PTV (D5) were calculated for all simulated setup error plans. Absolute dose measurements were performed using an ionization chamber in the junction. Results: The TH&TD plan produced a linear gradient in junction volume, comparable to that of the TH&TH plan. D5 of the PTV was 110% of the prescribed dose when the FFP plan was shifted 0.7 cm and 1.2 cm in the superior direction for 5-GVs and 7-GVs. D95 of the PTV decreased to < 90% of the prescribed dose when the FF plan was shifted 1.1 cm and 1.3 cm in the inferior direction for 5-GVs and 7-GVs. The absolute measured dose showed a good correlation with the calculated dose in the gradient junction volume. The average percent difference (±SD) in all measured points was − 0.7 ± 1.6%, and the average dose variations between depths was − 0.18 ± 1.07%. Conclusion: VGMT can create a linear dose gradient across the junction area in both TH&TH and TH&TD and can minimize the dose sensitivity to longitudinal setup errors in tomotherapy-based TBI.

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Section: Discussionsupporting

confidence: 87%

Feasibility of hybrid TomoHelical- and TomoDirect-based volumetric gradient matching technique for total body irradiation

Hong

Kim

et al. 2019

Radiat Oncol

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“…About 16(10) additional plans were generated for three isocenters (two isocenters) on the planning computed tomography images, 24 for a total of 204 plans. obtain eventual error E6 (9) obtain middle error E5 (8) spinal cord PCTV…”

Section: D | Dosimetric Effects Of the Longitudinal Directionmentioning

confidence: 99%

“…3 A technique for overcoming these challenges is to shift the field boundaries weekly. 4 Other techniques include extending the source-to-skin distance, 5 the interactive movement of the couch, 6 field-in-field, 7 a linear ramp-like dose profile, 8 jagged-junction IMRT 9 , and split-field IMRT (sfIMRT), 3,10 and so on. The technique of sfIMRT with linac has become a major strategy for optimizing the whole craniospinal target volume simultaneously that offers several advantages, such as easier formulation of the radiotherapy plan, easier setup, reduced delivery time, more homogeneous dose, and superior sparing of organs at risk.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the positional uncertainty of intrafraction, adjacent fields, and daily setup with the BrainLAB ExacTrac system in patients who are receiving craniospinal irradiation

Duan

Zhou

Dai

et al. 2020

J Applied Clin Med Phys

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Purpose: To investigate the daily setup, interfraction motion, variability in the junction areas, and dosimetric effect in craniospinal irradiation (CSI) patients. Methods: Fifteen CSI patients who had undergone split-field IMRT were followed in the study. Previous, middle, and posttreatment, each target volume position was evaluated using the ExacTrac system. Interfraction and intrafraction motions, the margin of the junction in adjacent targets volumes, and the dosimetric effect of the longitudinal residual error were analyzed. Results: The lowest attainment rate within the tolerance of the initial setup error was 66.79% in six directions. The values of the initial error were within 15 mm (SD 4.5 mm) in the translation direction and 5°(SD 1.3°) in the rotation direction after the transposition of the treatment isocenter. With the guidance of the ExacTrac system, the interfraction and intrafraction residual errors were almost within the tolerance after correction, the margin of CTV-to-PCTV was in the range of target expansion criteria. The residual longitudinal errors resulted in only slight changes in the mean doses of PGTV and PCTV, while the maximum dose of the spinal cord increased by 16.1%. The patients did not exhibit any side-effects by the overall treatment during the follow-up period. Conclusions: Position correction is necessary after setup and the transposition of the treatment isocenter. Intra-fraction motion in the lateral direction should be monitored throughout treatment. The position errors in junction areas are almost within the tolerance after correction. The patients did not exhibit any side-effects by the overall treatment.

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“…Though VMAT can deliver similar dose distributions as helical tomotherapy (HT), one (or more) treatment junction(s) is necessary to cover the entire length of the treatment volume when using VMAT . However, treatment junctions with VMAT add significant complexity to CSI planning and treatment delivery, and increase the potential for errors . Image‐guided RT (IGRT) in conjunction with VMAT allows for the adjustment and positional correction of the patient or treatment fields based on daily low‐dose kilovoltage imaging to account for daily setup variability.…”

Section: Introductionmentioning

confidence: 99%

“…[21][22][23] However, treatment junctions with VMAT add significant complexity to CSI planning and treatment delivery, and increase the potential for errors. 24 Image-guided RT (IGRT) in conjunction with VMAT allows for the adjustment and positional correction of the patient or treatment fields based on daily low-dose kilovoltage imaging to account for daily setup variability. There are scant reports of CSI with VMAT or IMRT.…”

Section: Introductionmentioning

confidence: 99%

Acute toxicity of craniospinal irradiation with volumetric‐modulated arc therapy in children with solid tumors

Wong

Ragab

Tran

et al. 2018

Pediatric Blood & Cancer

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Reducing the dosimetric impact of positional errors in field junctions for craniospinal irradiation using VMAT

Abstract: Background: Craniospinal irradiation (CSI) is considered technically challenging because the

Cited by 22 publications

References 27 publications

Feasibility of hybrid TomoHelical- and TomoDirect-based volumetric gradient matching technique for total body irradiation

Feasibility of hybrid TomoHelical- and TomoDirect-based volumetric gradient matching technique for total body irradiation

Evaluating the positional uncertainty of intrafraction, adjacent fields, and daily setup with the BrainLAB ExacTrac system in patients who are receiving craniospinal irradiation

Acute toxicity of craniospinal irradiation with volumetric‐modulated arc therapy in children with solid tumors

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