Improvement of therapeutic index for brain tumors with daily image guidance

Shields, Lisa B. E.; Coons, James M; Dedich, C.; Ragains, M.; Scalf, Kristi; Vitaz, Todd W.; Spalding, Aaron C.

doi:10.1186/1748-717x-8-283

Cited by 5 publications

(7 citation statements)

References 17 publications

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“…Shields et al concluded that daily imaging allows application of individualized CTV expansion which decreases dose to OAR and can lead to benefit in terms of neurocognition, learning, and neuroendocrine function. [19] Limitations of the present study include that it is retrospective in nature. Furthermore, the study does not include long-term clinical follow-up of the patients.…”

Section: Discussionmentioning

confidence: 94%

“…A study done by Shields et al showed that the first three days of CBCT predicted setup uncertainty for subsequent treatments and permitted customized CTV to PTV expansion although it was not statistically significant. [19] CBCTs were reviewed to assess the added benefit of using a 6D couch over conventional couch (in which shifts are applied in three directions -vertical, longitudinal, and lateral). During CBCT analysis, the shifts which had been applied at the time of treatment were negated and position was set as acquisition position.…”

Section: Discussionmentioning

confidence: 99%

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Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Pruthi¹,

Nagpal²,

Pandey³

2022

JNRP

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Objectives: Image-guided radiotherapy maximizes therapeutic index of brain irradiation by reducing setup errors during treatment. The aim of study was to analyze setup errors in the radiation treatment of glioblastoma multiforme and if decrease in planning target volume (PTV), margin is feasible using daily cone beam CT (CBCT) and 6D couch correction. Materials and Methods: Twenty-one patients (630 fractions of radiotherapy) were studied in which corrections were made in 6° of freedom. We determined setup errors, impact of setup errors of initial three fractions CBCT versus rest of the treatment with daily CBCT, and mean difference in setup errors with or without application of 6D couch and volumetric benefit of reduction of PTV margin from 0.5 cm to 0.3 cm. Results: The mean shift in the conventional directions, namely, vertical, longitudinal, and lateral was 0.17 cm, 0.19 cm, and 0.11 cm. There was significant change in vertical shift when first three fractions were compared with rest of the treatment with daily CBCT. When the effect of 6D couch was nullified, all directions showed increased error with longitudinal shift being significant. The number of setup errors of magnitude >0.3 cm was more significant when only conventional shifts were applied as compared with 6D couch. There was significant decrease in volume of brain parenchyma irradiated when margin of PTV was reduced from 0.5 cm to 0.3 cm. Conclusion: Daily CBCT along with 6D couch correction can reduce setup error which allows reduction in PTV margin during radiotherapy planning in turn improving the therapeutic index.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Pruthi¹,

Nagpal²,

Pandey³

2022

JNRP

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Section: Discussionmentioning

confidence: 99%

“…Safely reducing planning margins, while adequately treating tumour volumes, can decrease dose to normal brain tissue and critical OAR, leading to better functional outcomes for patients with brain tumours. 16 Decreasing the tumour volume may also potentially increase tumour control or reduce radiation-induced side effects for patients with a meningioma diagnosis. 17 Although the findings suggest the MFD provides better daily reproducibility statistically, there is not enough clinical significance to suggest one device gives superior daily positioning than the other.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of accuracy and reproducibility of a relocatable maxillary fixation system for fractionated intracranial stereotactic radiation therapy

Russo

Owen

Bernard

et al. 2015

J of Medical Radiation Sci

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IntroductionAccurate localisation is an essential component for the delivery of intracranial stereotactic treatment. For fractionated stereotactic radiotherapy, we compared the daily localisation accuracy of a standard thermoplastic mask with a new maxillary fixation device (MFD).MethodsDaily pre‐treatment kV cone‐beam computed tomography (CBCT) scans of 23 patients (12 localised in the MFD and 11 in the mask) with benign skull‐based lesions were reviewed retrospectively. The set up accuracy was measured in 6° of freedom, to ascertain both individual and population random and systematic errors. The appropriate clinical target volume to planning target volume margin was computed from set up error data.ResultsA total of 682 CBCT scans were evaluated. Systematic (Σ) and random (σ) population errors were Σ = 0.8 mm, 0.2 mm and 0.2 mm and σ = 0.3 mm, 0.3 mm and 0.2 mm, respectively, for the standard mask in the left/right (LR), superior/inferior (SI), and anterior/posterior (AP) translational planes, and Σ = 0.2 mm, 0.1 mm and 0.2 mm and σ = 0.2 mm, 0.3 mm and 0.2 mm, respectively, for the MFD. There was a reduction in rotation errors in the MFD compared to the mask. Margin calculations suggested an isotropic margin could be safely reduced to 2 mm for the MFD.ConclusionThe two devices demonstrate similar daily positional accuracy for fractionated stereotactic treatment of intracranial lesions. Combined with daily image guidance and couch correction, either of these devices is a viable frameless option for fractionated stereotactic radiation therapy.

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“…As proton dose distribution is susceptible to the heterogeneity along the beam path, the impact of setup uncertainties is of interest. In the setup of intracranial patients, orthogonal kV and cone-beam computed tomography (CT) are used as image guidance to position the patients under mask [ 19 – 21 ] and result in a distribution of setup uncertainties. Our current clinical treatment planning system Eclipse (Varian, Palo Alto, California) offers a robust optimization module that optimizes the spot intensities to provide sufficient target coverage under the worst setup and range uncertainty scenarios.…”

Section: Introductionmentioning

confidence: 99%

A Probability-Based Investigation on the Setup Robustness of Pencil-beam Proton Radiation Therapy for Skull-Base Meningioma

Zou

Kurtz

Nakib

et al. 2021

International Journal of Particle Therapy

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Introduction The intracranial skull-base meningioma is in proximity to multiple critical organs and heterogeneous tissues. Steep dose gradients often result from avoiding critical organs in proton treatment plans. Dose uncertainties arising from setup errors under image-guided radiation therapy are worthy of evaluation. Patients and Methods Fourteen patients with skull-base meningioma were retrospectively identified and planned with proton pencil beam scanning (PBS) single-field uniform dose (SFUD) and multifield optimization (MFO) techniques. The setup uncertainties were assigned a probability model on the basis of prior published data. The impact on the dose distribution from nominal 1-mm and large, less probable setup errors, as well as the cumulative effect, was analyzed. The robustness of SFUD and MFO planning techniques in these scenarios was discussed. Results The target coverage was reduced and the plan dose hot spot increased by all setup uncertainty scenarios regardless of the planning techniques. For 1 mm nominal shifts, the deviations in clinical target volume (CTV) coverage D99% was −11 ± 52 cGy and −45 ± 147 cGy for SFUD and MFO plans. The setup uncertainties affected the organ at risk (OAR) dose both positively and negatively. The statistical average of the setup uncertainties had <100 cGy impact on the plan qualities for all patients. The cumulative deviations in CTV D95% were 1 ± 34 cGy and −7 ± 18 cGy for SFUD and MFO plans. Conclusion It is important to understand the impact of setup uncertainties on skull-base meningioma, as the tumor target has complex shape and is in proximity to multiple critical organs. Our work evaluated the setup uncertainty based on its probability distribution and evaluated the dosimetric consequences. In general, the SFUD plans demonstrated more robustness than the MFO plans in target coverages and brainstem dose. The probability-weighted overall effect on the dose distribution is small compared to the dosimetric shift during single fraction.

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Improvement of therapeutic index for brain tumors with daily image guidance

Cited by 5 publications

References 17 publications

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Evaluation of accuracy and reproducibility of a relocatable maxillary fixation system for fractionated intracranial stereotactic radiation therapy

A Probability-Based Investigation on the Setup Robustness of Pencil-beam Proton Radiation Therapy for Skull-Base Meningioma

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