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| 2. |
- Ceberg, Crister, et al.
(författare)
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Photon activation therapy of RG2 glioma carrying Fischer rats using stable thallium and monochromatic synchrotron radiation.
- 2012
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 57:24, s. 8377-8391
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Tidskriftsartikel (refereegranskat)abstract
- 75 RG2 glioma-carrying Fischer rats were treated by photon activation therapy (PAT) with monochromatic synchrotron radiation and stable thallium. Three groups were treated with thallium in combination with radiation at different energy; immediately below and above the thallium K-edge, and at 50 keV. Three control groups were given irradiation only, thallium only, or no treatment at all. For animals receiving thallium in combination with radiation to 15 Gy at 50 keV, the median survival time was 30 days, which was 67% longer than for the untreated controls (p = 0.0020) and 36% longer than for the group treated with radiation alone (not significant). Treatment with thallium and radiation at the higher energy levels were not effective at the given absorbed dose and thallium concentration. In the groups treated at 50 keV and above the K-edge, several animals exhibited extensive and sometimes contra-lateral edema, neuronal death and frank tissue necrosis. No such marked changes were seen in the other groups. The results were discussed with reference to Monte Carlo calculated electron energy spectra and dose enhancement factors.
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| 3. |
- Ceberg, Sofie, et al.
(författare)
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Surface guided radiotherapy decreases the uncertainty in breast cancer patient setup
- 2018
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Konferensbidrag (refereegranskat)abstract
- (Sunday, 7/29/2018) 3:00 PM - 6:00 PMRoom: Exhibit HallPurpose: The aim was to investigate if the setup of breast cancer patients could be improved using surface guided radiotherapy, compared to the conventional method using lasers and skin markings.Methods: Forty-seven patients, who received tangential or locoregional adjuvant radiotherapy, were positioned using a surface-based setup (SBS). Thirty-eight patients were positioned using the conventional laser-based setup (LBS). For the patient group positioned using a SBS, correction for posture was performed under guidance of a color map projected onto the patients' skin in real time. The surface tolerance for the color map was 5 mm. For both setup techniques the deviation of the breast position was measured using verification images. In total, 897 images were analysed. The frequency distributions of the deviations were analysed.Results: The result showed a significant improvement in the interfractional variation of the setup deviation for SBS compared to the LBS (pConclusion: Conventional laser-based setup can be replaced by surface-based setup, both for tangential and locoregional breast cancer treatments.
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| 4. |
- Dasu, Alexandru, et al.
(författare)
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Normal tissue sparing potential of scanned proton beams with and without respiratory gating for the treatment of internal mammary nodes in breast cancer radiotherapy
- 2018
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Ingår i: Physica medica (Testo stampato). - : Elsevier BV. - 1120-1797 .- 1724-191X. ; 52, s. 81-85
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Tidskriftsartikel (refereegranskat)abstract
- Proton therapy has shown potential for reducing doses to normal tissues in breast cancer radiotherapy. However data on the impact of protons when including internal mammary nodes (IMN) in the target for breast radiotherapy is comparatively scarce. This study aimed to evaluate normal tissue doses when including the IMN in regional RT with scanned proton beams, with and without respiratory gating. The study cohort was composed of ten left-sided breast patients CT-scanned during enhanced inspiration gating (EIG) and free-breathing (FB). Proton plans were designed for the target including or excluding the IMN. Targets and organs-at-risk were delineated according to RTOG guidelines. Comparison was performed between dosimetric parameters characterizing target coverage and OAR radiation burden. Statistical significance of differences was tested using a paired, two-tailed Student's t-test. Inclusion of the IMN in the target volume led to a small increase of the cardiopulmonary burden. The largest differences were seen for the ipsilateral lung where the mean dose increased from 6.1 to 6.6 Gy (RBE) (P < 0.0001) in FB plans and from 6.9 to 7.4 Gy (RBE) (P = 0.003) in EIG plans. Target coverage parameters were very little affected by the inclusion of IMN into the treatment target. Radiotherapy with scanned proton beams has the potential of maintaining low cardiovascular burden when including the IMN into the target, irrespective of whether respiratory gating is used or not.
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| 5. |
- Edvardsson, Anneli, et al.
(författare)
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Comparative treatment planning study for mediastinal Hodgkin’s lymphoma : impact on normal tissue dose using deep inspiration breath hold proton and photon therapy
- 2019
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Ingår i: Acta Oncologica. - 0284-186X. ; 58:1, s. 95-104
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Tidskriftsartikel (refereegranskat)abstract
- Background: Late effects induced by radiotherapy (RT) are of great concern for mediastinal Hodgkin’s lymphoma (HL) patients and it is therefore important to reduce normal tissue dose. The aim of this study was to investigate the impact on the normal tissue dose and target coverage, using various combinations of intensity modulated proton therapy (IMPT), volumetric modulated arc therapy (VMAT) and 3-dimensional conformal RT (3D-CRT), planned in both deep inspiration breath hold (DIBH) and free breathing (FB). Material and methods: Eighteen patients were enrolled in this study and planned with involved site RT. Two computed tomography images were acquired for each patient, one during DIBH and one during FB. Six treatment plans were created for each patient; 3D-CRT in FB, 3D-CRT in DIBH, VMAT in FB, VMAT in DIBH, IMPT in FB and IMPT in DIBH. Dosimetric impact on the heart, left anterior descending (LAD) coronary artery, lungs, female breasts, target coverage, and also conformity index and integral dose (ID), was compared between the different treatment techniques. Results: The use of DIBH significantly reduced the lung dose for all three treatment techniques, however, no significant difference in the dose to the female breasts was observed. Regarding the heart and LAD doses, large individual variations were observed. For VMAT, the mean heart and LAD doses were significantly reduced using DIBH, but no significant difference was observed for 3D-CRT and IMPT. Both IMPT and VMAT resulted in improved target coverage and more conform dose distributions compared to 3D-CRT. IMPT generally showed the lowest organs at risk (OAR) doses and significantly reduced the ID compared to both 3D-CRT and VMAT. Conclusions: The majority of patients benefited from treatment in DIBH, however, the impact on the normal tissue dose was highly individual and therefore comparative treatment planning is encouraged. The lowest OAR doses were generally observed for IMPT in combination with DIBH.
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| 7. |
- Edvardsson, Anneli
(författare)
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Dosimetric effects of breathing motion in radiotherapy
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The goal of radiotherapy is to deliver a homogeneous high dose of radiation to a tumour while minimising the dose to the surrounding healthy tissue. To achieve this, increasingly advanced treatment techniques, such as volumetric modulated arc therapy (VMAT) and proton therapy, have been developed. However, these treatment techniques are sensitive to patient motion, such as breathing, which may degrade the dose distribution to the tumour and healthy tissue. The simultaneous movement of the tumour and treatment delivery may cause unwanted heterogeneities in the dose distribution, so-called interplay effects. Treatment during deep inspiration (DI) could mitigate the motion and lead to favourable anatomical changes in the tumour position with respect to healthy tissue. The aim of the work presented in this thesis was to investigate various effects of breathing motion on the tumour and healthy tissue dose distribution in radiotherapy.Potential healthy tissue dose sparing using DI photon or proton therapy was investigated for left-sided breast cancer and mediastinal Hodgkin’s lymphoma (HL) by performing comparative treatment planning studies. The use of DI reduced the dose to healthy tissue for left-sided breast cancer patients. It also reduced the healthy tissue dose for most mediastinal HL patients, but the benefits were more patient specific due to large variations in the disease distribution. Protons reduced the dose to healthy tissue for both left-sided breast cancer and mediastinal HL patients compared to photons, regardless of the use of DI.A tool to simulate breathing-motion-induced interplay effects for VMAT was developed and used to investigate how interplay effects vary for different treatment scenarios. The tool was further adapted for use in a more clinical setting to investigate interplay effects for stereotactic VMAT treatment of liver metastases. Interplay effects were shown to negatively affect the dose distribution, resulting in underdosing part of the tumour. The extent of interplay effects depended on the tumour motion and treatment plan characteristics. In conclusion, major dosimetric effects of breathing motion on radiotherapy treatment were demonstrated by the work presented in this thesis. A beneficial effect of reduced healthy tissue dose was observed when the patient used controlled DI. Furthermore, by knowing the breathing-induced motion of the tumour, the treatment delivery parameters can be selected wisely to minimise unwanted interplay effects. Knowledge of the dosimetric effects of breathing motion is important to be able to individually optimise the radiotherapy treatment.
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| 8. |
- Edvardsson, Anneli, et al.
(författare)
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Motion induced interplay effects for VMAT radiotherapy
- 2018
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 63:8
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to develop a method to simulate breathing motion induced interplay effects for volumetric modulated arc therapy (VMAT), to verify the proposed method with measurements, and to use the method to investigate how interplay effects vary with different patient-and machine specific parameters. VMAT treatment plans were created on a virtual phantom in a treatment planning system (TPS). Interplay effects were simulated by dividing each plan into smaller sub-arcs using an in-house developed software and shifting the isocenter for each sub-arc to simulate a sin(6) breathing motion in the superior-inferior direction. The simulations were performed for both flattening-filter (FF) and flattening-filter free (FFF) plans and for different breathing amplitudes, period times, initial breathing phases, dose levels, plan complexities, CTV sizes, and collimator angles. The resulting sub-arcs were calculated in the TPS, generating a dose distribution including the effects of motion. The interplay effects were separated from dose blurring and the relative dose differences to 2% and 98% of the CTV volume (Delta D-98% and Delta D-2%) were calculated. To verify the simulation method, measurements were carried out, both static and during motion, using a quasi-3D phantom and a motion platform. The results of the verification measurements during motion were comparable to the results of the static measurements. Considerable interplay effects were observed for individual fractions, with the minimum Delta D-98% and maximum Delta D-2% being - 16.7% and 16.2%, respectively. The extent of interplay effects was larger for FFF compared to FF and generally increased for higher breathing amplitudes, larger period times, lower dose levels, and more complex treatment plans. Also, the interplay effects varied considerably with the initial breathing phase, and larger variations were observed for smaller CTV sizes. In conclusion, a method to simulate motion induced interplay effects was developed and verified with measurements, which allowed for a large number of treatment scenarios to be investigated. The simulations showed large interplay effects for individual fractions and that the extent of interplay effects varied with the breathing pattern, FFF/FF, dose level, CTV size, collimator angle, and the complexity of the treatment plan.
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| 9. |
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| 10. |
- Edvardsson, Anneli, et al.
(författare)
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Robustness and dosimetric verification of hippocampal-sparing craniospinal pencil beam scanning proton plans for pediatric medulloblastoma
- 2024
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Ingår i: Physics and Imaging in Radiation Oncology. - : Elsevier. - 2405-6316. ; 29
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Tidskriftsartikel (refereegranskat)abstract
- Background and PurposeHippocampal-sparing (HS) is a method that can potentially reduce late cognitive complications for pediatric medulloblastoma (MB) patients treated with craniospinal proton therapy (PT). The aim of this study was to investigate robustness and dosimetric plan verification of pencil beam scanning HS PT.Materials and MethodsHS and non-HS PT plans for the whole brain part of craniospinal treatment were created for 15 pediatric MB patients. A robust evaluation of the plans was performed. Plans were recalculated in a water phantom and measured field-by-field using an ion chamber detector at depths corresponding to the central part of hippocampi. All HS and non-HS fields were measured with the standard resolution of the detector and in addition 16 HS fields were measured with high resolution. Measured and planned dose distributions were compared using gamma evaluation.ResultsThe median mean hippocampus dose was reduced from 22.9 Gy (RBE) to 8.9 Gy (RBE), while keeping CTV V95% above 95 % for all nominal HS plans. HS plans were relatively robust regarding hippocampus mean dose, however, less robust regarding target coverage and maximum dose compared to non-HS plans. For standard resolution measurements, median pass rates were 99.7 % for HS and 99.5 % for non-HS plans (p < 0.001). For high-resolution measurements, median pass rates were 100 % in the hippocampus region and 98.2 % in the surrounding region.ConclusionsA substantial reduction of dose in the hippocampus region appeared feasible. Dosimetric accuracy of HS plans was comparable to non-HS plans and agreed well with planned dose distribution in the hippocampus region.
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