Re-irradiation of spinal column metastases by IMRT: impact of setup errors on the dose distribution

Gröger, Christian; Hautmann, Matthias G.; Loeschel, Rainer; Repp, Natalia; Kölbl, Oliver; Dobler, Barbara

doi:10.1186/1748-717x-8-269

Cited by 5 publications

(5 citation statements)

References 22 publications

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“…CT data of ten patients with spinal column metastases who had previously been treated with 3D-CRT were selected from our treatment database. These data had previously been used for another study with identical delineation of the planning target volume (PTV) and organs at risk (OAR) and dose prescription [ 29 ]. The PTV of the first course (pre-irradiation) consisted of the 1–5 thoracic vertebrae including the spinal cord.…”

Section: Methodsmentioning

confidence: 99%

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Re-irradiating spinal column metastases using IMRT and VMAT with and without flattening filter - a treatment planning study

et al. 2016

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BackgroundThe aim of this study was to investigate the potential of the flattening filter free (FFF) mode of a linear accelerator for intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for patients with in-field recurrence of vertebral metastases.MethodsAn Elekta Synergy Linac with Agility™ head is used to simulate the treatment of ten patients with locally recurrent spinal column metastases. Four plans were generated for each patient treating the vertebrae sparing the spinal cord: Dual arc VMAT and nine field step and shoot IMRT each with and without flattening filter. Plan quality was assessed considering target coverage and sparing of the spinal cord and normal tissue. All plans were verified by a 2D-ionisation-chamber-array, peripheral doses were measured and compared to calculations. Delivery times were measured and compared. The Wilcoxon test was used for statistical analysis with a significance level of 0.05.ResultsTarget coverage, homogeneity index and conformity index were comparable for both flat and flattening filter free beams. The volume of the spinal cord receiving the allowed maximum dose to keep the risk of radiation myelopathy at 0 % was at the same time significantly reduced to below the clinically relevant 1 ccm using FFF mode. In addition the mean dose deposited in the surrounding healthy tissue was significantly reduced in the FFF mode. All four techniques showed equally good gamma scores for plan verification. FFF plans required considerably more MU per fraction dose. Regardless of the large number of MU, out-of-field point dose was significantly lower for FFF plans, with an average reduction of 33 % and mean delivery time was significantly reduced by 22 % using FFF beams. When compared to IMRT FF, VMAT FFF offered even a reduction of 71 % in delivery time and 45 % in peripheral dose.ConclusionsFFF plans showed a significant improvement in sparing of normal tissue and the spinal cord, keeping target coverage and homogeneity comparable. In addition, delivery times were significantly reduced for FFF treatments, minimizing intrafractional motion as well as strain for the patient. Shortest delivery times were achieved using VMAT FFF. For radiotherapy of spinal column metastases VMAT FFF may therefore be considered the preferable treatment option for the combination of Elekta Synergy Linacs and Oncentra® External Beam v4.5 treatment planning system.

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Section: Methodsmentioning

confidence: 99%

“…a 0 % risk of radiation myelopathy. Details about the calculation are described in Groeger et al [ 29 ].…”

Section: Methodsmentioning

confidence: 99%

Re-irradiating spinal column metastases using IMRT and VMAT with and without flattening filter - a treatment planning study

et al. 2016

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“…Reports on dosimetry changes brought about by radiotherapy set‐up errors are concerned with head and neck tumors such as nasopharyngeal tumors, intracranial tumors, abdominal pelvic tumors, etc. The dosimetry changes generated by vertebral set‐up error are only related to the study on re‐irradiation . The side effect of radiotherapy is directly related to the dose of irradiation, so radiotherapy for tumor of the spine is often limited to low‐dose palliative treatment, which makes it difficult to obtain satisfactory therapeutic effect.…”

Section: Discussionmentioning

confidence: 99%

“…Set‐up error of 1 cm may cause the spinal cord to fall into the high dose area, resulting in serious consequences [81]. Gröger et al studied 10 cases of thoracic metastatic tumor (irradiation range 1–5 vertebral body) and discovered that average set‐up error was 6.1 ± 4 mm in translation direction and 2.7° ± 1.1° in rotation direction. Comparison of dosimetry parameters without set‐up error correction and after set‐up error correction in simulation IMRT: CTV95% prescription dose target areas were 81.6% and 86.6% respectively; PTV95% prescription dose target area were 79.4% and 89.9%; average maximum dose point of the spinal cord D0.1cc were 20.4 and 18.0 Gy.…”

Section: Discussionmentioning

confidence: 99%

Set‐up error and dosimetric analysis of HexaPOD evo RT 6D couch combined with cone beam CT image‐guided intensity‐modulated radiotherapy for primary malignant tumor of the cervical spine

Jiang

Zhang

Wei

et al. 2020

J Applied Clin Med Phys

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Purpose: To investigate the set-up error and consequent dosimetric change in HexaPOD evo RT 6D couch under image-guided intensity-modulated radiotherapy (IG-IMRT) for primary malignant tumor of the cervical spine. Methods: Ten cases with primary malignant tumor of the cervical spine were treated with intensity-modulated radiotherapy (IMRT) in our hospital from August 2013 to November 2014. The X-ray volumetric images (XVI) were scanned and obtained by cone-beam CT (CBCT). The six directions (6D) of set-up errors of translation and rotation were obtained by planned CT image registration. HexaPOD evo RT 6D couch made online correction of the set-up error, and then the CBCT was conducted to obtain the residual error. Results: We performed set-up error and dosimetric analysis. First, for the set-up error analysis, the average error in three translation directions of 6D set-up error of the primary tumor of the cervical spine was <2 mm, whereas the single maximum error (absolute value) is 7.0 mm. Among average errors of rotation direction, Rotation X (RX)direction 0.67°± 0.04°, Rotation Y (RY) direction 1.06°± 0.06°, Rotation Z (RZ) direction 0.78°± 0.05°; and the single maximum error in three rotation directions were 2.8°, 3.8°, and 2.9°, respectively. On three directions (X, Y, Z axis), the extended distance from clinical target volume (CTV) to planning target volume (PTV) was 3.45, 3.17, and 3.90 mm by calculating, respectively. Then, for the dosimetric analysis, the parameters, including plan sum PTV D98 and D95, planning gross tumor volume D98 and D95, V100% of the plan sum were significantly lower than the treatment plan.Moreover, Dmax of the spinal cord was significantly higher than the treatment plan. Conclusion: 6D set-up error correction system should be used for accurate position calibration of precise radiotherapy for patients with malignant tumor of the cervical spine. K E Y W O R D S cervical spinal tumor, dosimetric analysis, IMRT This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…In this context, the usefulness of IGRT systems is in relation to the necessity of sparing the OARs, such as the eye and the optic nerves in case of re-irradiation of craniofacial volumes, the spinal cord in case of re-irradiation of vertebral metastasis or, finally, the rectum and the bladder in the case of pelvic targets re-irradiation [61][62][63].…”

Section: Re-irradiationmentioning

confidence: 99%

Image-guided radiation therapy (IGRT): practical recommendations of Italian Association of Radiation Oncology (AIRO)

et al. 2016

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The use of imaging to maximize precision and accuracy throughout the entire process of radiation therapy (RT) delivery has been called "Image-guided RT" (IGRT). RT has long been image guided: in fact, historically, the portal films and later electronic megavoltage images represented an early form of IGRT. A broad range of IGRT modalities is now available and adopted. The target location may be defined for each treatment fraction by several methods by localizing surrogates, including implanted fiducial markers, external surface markers or anatomical features (through planar imaging, fluoroscopy, KV or MV computed tomography, magnetic resonance imaging, ultrasound and X-ray imaging, electromagnetic localization, optical surface imaging, etc.). The aim of the present review is to define practical recommendations for IGRT.

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Re-irradiation of spinal column metastases by IMRT: impact of setup errors on the dose distribution

Cited by 5 publications

References 22 publications

Re-irradiating spinal column metastases using IMRT and VMAT with and without flattening filter - a treatment planning study

Re-irradiating spinal column metastases using IMRT and VMAT with and without flattening filter - a treatment planning study

Set‐up error and dosimetric analysis of HexaPOD evo RT 6D couch combined with cone beam CT image‐guided intensity‐modulated radiotherapy for primary malignant tumor of the cervical spine

Image-guided radiation therapy (IGRT): practical recommendations of Italian Association of Radiation Oncology (AIRO)

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