| 1. |
- Bjoreland, Anders, et al.
(författare)
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Liquid ionization chamber calibrated gel dosimetry in conformal stereotactic radiotherapy of brain lesions
- 2008
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Ingår i: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 47:6, s. 1099-1109
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Tidskriftsartikel (refereegranskat)abstract
- Hypofractionated conformal stereotactic radiotherapy (HCSRT) is an established method of treating brain lesions such as arteriovenous malformations (AVMs) and brain metastases. The aim of this study was to investigate the reliability of treatment plans in the terms of dose distribution and absorbed dose for HCSRT. Methods and materials. Treatment plans for three different clinical intracerebral targets, AVMs, were transferred to a CT study of a spherical water filled phantom simulating the human head and recalculated for the phantom geometry using a standard treatment planning system utilizing a pencil beam algorithm for dose calculation. The calculated absorbed dose, relative three dimensional (3D) dose distribution and dose conformity were investigated using gel dosimetry normalized to liquid ionization chamber (LIC) measurements. Results. The measured absorbed dose to the dose reference point was found to be within 2% of the calculated dose for all three targets. The measured dose distribution was found to be within 3% and 2 mm of the calculated dose for more than 93% of all points in the target volume for all three targets. Conclusions. The results show that the investigated standard treatment planning system can correctly predict the absorbed dose and dose distribution in different types of intracerebral targets and that the treatment can be delivered according to the plan.
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| 2. |
- Lindvall, Peter, et al.
(författare)
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A comparison between surgical resection in combination with WBRT or hypofractionated stereotactic irradiation in the treatment of solitary brain metastases.
- 2009
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Ingår i: Acta Neurochirurgica. - : Springer Science and Business Media LLC. - 0001-6268 .- 0942-0940. ; 151:9, s. 1053-1059
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The standard treatment of solitary brain metastases previously has been tumour resection in combination with whole-brain radiation therapy (WBRT). Stereotactic radiotherapy has emerged as a non-invasive treatment option especially for small brain metastases. We now report our results on resection + WBRT or hypofractionated stereotactic irradiation (HCSRT) in the treatment of solitary brain metastases. METHODS: Between 1993 and 2004 patients with metastatic cancer and solitary brain metastases were selected for surgical resection + WBRT or HCSRT alone at the Umeå University Hospital. Fifty-nine patients were treated with surgical resection + WBRT (34 male, 25 female, mean age 63.3 years). Forty-seven patients were treated with HCSRT alone (15 male, 32 female, mean age 64.9 years). FINDINGS: In patients followed radiologically, 28% treated with resection + WBRT showed a local recurrence after a median time of 8.0 months, whereas there was a lack of local control in 16% in the HCSRT group after a median time of 3.0 months. There was a significantly longer survival time for patients treated with resection + WBRT (median 7.9, mean 12.9 months) compared to HCSRT (median 5.0, mean 7.6 months). Even in patients with a tumour volume <10 cc, there was a significantly longer survival in favour of resection + WBRT (median 8.4, mean 17.4 months) compared to HCSRT (median 5.0, mean 7.9 months). CONCLUSION: This retrospective and non-randomised study indicates that surgical resection in combination with WBRT may be an option even for small brain metastases suitable for treatment with HCSRT. Since survival and local control following resection + WBRT was at least as favourable as compared to HCSRT alone, tumour location and expected neurological outcome may be the strongest aspect when selecting treatment modality.
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| 3. |
- Lindvall, Peter, et al.
(författare)
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Cerebral metabolism during air transport of patients after surgery for malignant glioma
- 2008
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Ingår i: Aviation, Space and Environmental Medicine. - 0095-6562 .- 1943-4448. ; 79:7, s. 700-703
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Post-operative air transport of patients following an intracranial procedure is not uncommon. The transport itself may pose a risk, and if there are harmful effects to the brain this should be reflected in the brain metabolism. The aim of this study was to analyze possible alterations in cerebral metabolism that could be caused by air transport.METHODS: Four patients with glioblastomas were operated with a biopsy or a craniotomy. During this procedure microdialysis catheters were placed in tumor tissue or brain adjacent to tumor and in normal cerebral tissue. In this study we have analyzed cerebral glucose metabolites (glucose, lactate / pyruvate ratio), glycerol, and glutamate at five time points during a 24-h period including air transport.RESULTS: Analyzing mean values, there was a small but significant increase in the lactate/pyruvate ratio from 45.18 to 47.78 in normal cerebral tissue after air transport compared to a previous fasting sample. For tumor tissue there was a small decrease in glucose from 1.04 to 0.92 mmol L(-1) and an increase in glutamate from 13.08 to 19.06 micromol L(-1). There were no other significant differences in the analyzed cerebral metabolites after air transport.DISCUSSION: There were only minor differences in levels of cerebral metabolites after air transport compared to a previous fasting sample. Thus it seems that air transportation of the four reported patients did not cause any major cellular damage or metabolic changes as assessed by extracellular glucose, lactate/pyruvate ratio, glycerol, or glutamate.
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| 4. |
- Lindvall, Peter, et al.
(författare)
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Combined effects of embolisation and hypofractionated conformal stereotactic radiotherapy in arteriovenous malformations of the brain
- 2005
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Ingår i: INTERVENTIONAL NEURORADIOLOGY. - Milan, Udine, Italy : Edizioni del Centauro. - 1123-9344. ; 11:3, s. 223-229
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Tidskriftsartikel (refereegranskat)abstract
- There are three major treatment options for cerebral AVMs; surgery, embolization and radiosurgery. Embolization may be effective to reduce the size and density but completely obliterates AVMs only in a minority of cases. Radiosurgery may be an alternative to resection, especially in smaller AVMs. Large AVMs have been considered difficult to treat safely and effectively with single fraction radiosurgery. Hypofractionated conformal stereotactic radiotherapy (HCSRT)alone or in combination with embolization may be an alternative treatment. Embolization may reduce the volume and density of AVMs, followed by HCSRT, allowing a safe delivery of a higher total dose of radiation than possible with a single fraction. Sixteen patients with AVMs were treated with embolization and HCSRT. Embolization was performed in 1-6(median 2) sessions. HCSRT was delivered in 5fractions with 6-7 Gy each to the total dose of30–35 Gy. Cerebral angiographies before and after embolization were digitally compared for calculation of volume reduction and luminescence as a measure of AVM density. The mean AVM volume in 15 patients was reduced from11.9 ± 2.1 (1-29, median 10.0) ml to 6.5 ± 2.0(0.5–28, median 3) ml by embolization. The luminescence for all AVMs was significantly higher after than before embolization, indicating that all AVMs were less dense after embolization. Thirteen out of 16 patients (13/16, 81%) treatedwith embolization and HCSRT have so farshown obliteration of their AVMs 2-9 (median4) years after HCSRT. Three patients experienced neurological sequele after embolization, and three patients developed radionecrosis after HCSRT. Using a new method to compare cerebral angiographies in AVMs we report reduction in density and volume after embolization. The obliteration rate of a combined treatment with embolization and HCSRT seems comparable with single fraction radiosurgery although the AVMs in our series are larger than reported in most series treated with single fraction radiosurgery.
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| 5. |
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| 6. |
- Lindvall, Peter, et al.
(författare)
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Hypofractionated stereotactic radiotherapy in medium-sized to large arteriovenous malformations
- 2015
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Ingår i: Journal of clinical neuroscience. - : Elsevier BV. - 0967-5868 .- 1532-2653. ; 22:6, s. 955-958
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Tidskriftsartikel (refereegranskat)abstract
- We have reviewed treatment results in terms of obliteration and complications in 24 patients with medium to large sized cerebral arteriovenous malformations (AVMs) (mean volume 18.5 +/- 8.9 cm(3); range: 10-42) treated with hypofractionated stereotactic radiotherapy (HSRT). AVMs are congenital lesions associated with a high morbidity and mortality. Radiosurgery is one option for treatment. However, in larger AVMs with volumes exceeding 10 cm(3) obliteration rates are less favourable and radiation induced complications more frequent. For larger AVMs, volume-staged radiosurgery is one option while another option may be the use of HSRT. Patients were treated with 6-7 Gy in five fractions to a total dose of 30-35 Gy (mean total dose 32.9 +/- 1.6 Gy [standard error of the mean]). Sixteen patients (69.6%) showed obliteration after a mean time of 35.2 +/- 14.8 months (range: 24-60). Only one patient (4.2%) experienced symptomatic radionecrosis. Our treatment with HSRT seems safe and efficient for treatment of medium to large sized AVMs. Treatment results seem to be in line with volume-staged radiosurgery and may be an alternative for AVMs not suitable for single fraction radiosurgery.
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| 7. |
- Lindvall, Peter, et al.
(författare)
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Radiation schedules in relation to obliteration and complications in hypofractionated conformal stereotactic radiotherapy of arteriovenous malformations
- 2010
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Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger AG. - 1011-6125 .- 1423-0372. ; 88:1, s. 24-28
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The purpose of this investigation was to assess the obliteration rate and complications following different radiation schedules of hypofractionated conformal stereotactic radiotherapy for cerebral arteriovenous malformations (AVMs). METHODS: Twenty-five patients were treated with 35 Gy in 5 fractions, whereas 31 patients were treated with 30-32.5 Gy (mean: 31.6 +/- 0.23 Gy) in 5 fractions. A complete angiographic follow-up is available for 40 patients. RESULTS: Thirty-seven out of 40 patients (92.5%) have so far shown obliteration of their AVMs after a mean time of 3.2 +/- 0.26 years (range: 2-8 years). The mean AVM volume in these patients was 8.2 +/- 1.0 cm(3) (range: 1.5-29 cm(3)). There was a higher rate of obliteration (88%) in patients treated with 35 Gy compared to those treated with < 35 Gy (78%), even if this was not statistically significant. There was a significantly shorter time to obliteration in patients treated with 35 Gy. All patients who experienced symptomatic radionecrosis belonged to the group treated with 35 Gy. CONCLUSION: A radiation schedule of 35 Gy in 5 fractions may be more effective than a radiation schedule of <35 (30-32.5) Gy in obliterating AVMs. This may, however, be at the price of an increased risk of symptomatic radionecrosis.
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| 8. |
- Lindvall, Peter, et al.
(författare)
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Reproducibility and geometric accuracy of the Fixster system during hypofractionated stereotactic radiotherapy
- 2008
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Ingår i: Radiation Oncology. - 1748-717X. ; 3:16
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Hypofractionated radiotherapy has been used for the treatment of AVMs and brain metastases. Hypofractionation necessitates the use of a relocatable stereotactic frame that has to be applied on several occasions. The stereotactic frame needs to have a high degree of reproducibility, and patient positioning is crucial to achieve a high accuracy of the treatment.METHODS:In this study we have, by radiological means, evaluated the reproducibility of the isocenter in consecutive treatment sessions using the Fixster frame. Deviations in the X, Y and Z-axis were measured in 10 patients treated with hypofractionated radiotherapy.RESULTS:The mean deviation in the X-axis was 0.4 mm (range -2.1 - 2.1, median 0.7 mm) and in the Y-axis -0.3 mm (range -1.4 - 0.7, median -0.2 mm). The mean deviation in the Z-axis was -0.6 (range -1.4 - 1.4, median 0.0 mm).CONCLUSION:There is a high degree of reproducibility of the isocenter during successive treatment sessions with HCSRT using the Fixster frame for stereotactic targeting. The high reducibility enables a safe treatment using hypofractionated stereotactic radiotherapy.
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