1,720,969 research outputs found
An automatic segmentation method of FDG-PET images based on Dirichlet process mixture model
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PO-0962: A Dirichlet process mixture model for automatic segmentation of 18F-FDG PET-CT images
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A Dirichlet process mixture model for automatic (18)F-FDG PET image segmentation: Validation study on phantoms and on lung and esophageal lesions
No full textThe aim of this study was to implement a Dirichlet process mixture (DPM) model for automatic tumor edge identification on (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) images by optimizing the parameters on which the algorithm depends, to validate it experimentally, and to test its robustness
IMRT or 3D-CRT in glioblastoma? A dosimetric criterion for patient selection
No full textIntensity modulated radiation therapy (IMRT) is increasingly employed in glioblastoma (GBM) treatment. The present work aimed to assess which clinical-dosimetric scenario could benefit the most from IMRT application, with respect to three-dimensional conformal radiation therapy (3D-CRT). The number of organs at risk (OARs) overlapping the planning target volume (PTV) was the parameter describing the clinical-dosimetric pattern. Based on the results, a dosimetric decision criterion to select the most appropriate treatment technique is provided. Seventeen previously irradiated patients were retrieved and re-planned with both 3D-CRT and IMRT. The prescribed dose was 60 Gy/30fx. The cases were divided into 4 groups (4 patients in each group). Each group represents the scenario where 0, 1, 2 or 3 OARs overlapped the target volume, respectively. Furthermore, in one case, 4 OARs overlapped the PTV. The techniques were compared also in terms of irradiated healthy brain tissue. The results were evaluated by paired t-test. IMRT always provided better target coverage (V95%) than 3D-CRT, regardless the clinical-dosimetric scenario: difference ranged from 0.82% (p = 0.4) for scenario 0 to 7.8% (p = 0.02) for scenario 3, passing through 2.54% (p = 0.18) and 5.93% (p = 0.08) for scenario 1 and 2, respectively. IMRT and 3D-CRT achieved comparable results in terms of dose homogeneity and conformity. Concerning the irradiation of serial-kind OARs, both techniques provided nearly identical results. A statistically significant dose reduction to the healthy brain in favor of IMRT was scored. IMRT seems a superior technique compared to 3D-CRT when there are multiple overlaps between OAR and PTV. In this scenario, IMRT allows for a better target coverage while maintaining equivalent OARs sparing and reducing healthy brain irradiation. The results from our patients dataset suggests that the overlap of three OARs can be used as a dosimetric criterion to select which patients should receive IMRT treatment
Gated reconstruction in 18FDG PET-CT quantitative imaging: impact on SUV estimation in lung tumors
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Dosimetria in vivo con film radiocromici in radioterapia intraoperatoria della mammella
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Regional hyperthermia combined with chemoradiotherapy in primary or recurrent locally advanced pancreatic cancer : an open-label comparative cohort trial.
No full textPURPOSE:
To evaluate the therapeutic effect of delivering regional hyperthermia (HT) plus chemoradiotherapy (CRT) in patients suffering from locally advanced unresectable pancreatic cancer (LAPC).
METHODS:
Between January 2000 and December 2008, 68 patients affected by primary (56/68) or recurrent (12/68) LAPC were treated either with CRT alone or CRT plus HT. Radiotherapy (RT) consisted of 3D conformal irradiation of tumor and regional lymph nodes (dose ranged from 30 Gy/10 fractions to 66 Gy/33 fractions). Chemotherapy (CT) consisted of gemcitabine (GEM) alone or in association with either oxaliplatin, cisplatin, or 5-FU. HT was delivered twice a week, concomitant with RT.
RESULTS:
In the current study, 60 of the original 68 patients were included. Median overall survival (OS) was 15 months in the HT group versus 11 months in the control group (log-rank test: p = 0.025). HT did not increase CRT toxicity.
CONCLUSION:
HT can be added safely to CRT in LAPC, thus, resulting in slightly prolonged survival in certain cases
Optimized PET Imaging for 4D Treatment Planning in Radiotherapy: the Virtual 4D PET Strategy
No full textThe purpose of the study is to evaluate the performance of a novel strategy, referred to as "virtual 4D PET", aiming at the optimization of hybrid 4D CT-PET scan for radiotherapy treatment planning. The virtual 4D PET strategy applies 4D CT motion modeling to avoid time-resolved PET image acquisition. This leads to a reduction of radioactive tracer administered to the patient and to a total acquisition time comparable to free-breathing PET studies. The proposed method exploits a motion model derived from 4D CT, which is applied to the free-breathing PET to recover respiratory motion and motion blur. The free-breathing PET is warped according to the motion model, in order to generate the virtual 4D PET. The virtual 4D PET strategy was tested on images obtained from a 4D computational anthropomorphic phantom. The performance was compared to conventional motion compensated 4D PET. Tests were also carried out on clinical 4D CT-PET scans coming from seven lung and liver cancer patients. The virtual 4D PET strategy was able to recover lesion motion, with comparable performance with respect to the motion compensated 4D PET. The compensation of the activity blurring due to motion was successfully achieved in terms of spill out removal. Specific limitations were highlighted in terms of partial volume compensation. Results on clinical 4D CT-PET scans confirmed the efficacy in 4D PET count statistics optimization, as equal to the free-breathing PET, and recovery of lesion motion. Compared to conventional motion compensation strategies that explicitly require 4D PET imaging, the virtual 4D PET strategy reduces clinical workload and computational costs, resulting in significant advantages for radiotherapy treatment planning
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