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Virtual modelling of novel applicator prototypes for cervical cancer brachytherapy
Primož Petrič, Robert Hudej, Noora Al-Hammadi, Barbara Šegedin, 2016, original scientific article

Abstract: Standard applicators for cervical cancer Brachytherapy (BT) do not always achieve acceptable balance between target volume and normal tissue irradiation. We aimed to develop an innovative method of Targetvolume Density Mapping (TDM) for modelling of novel applicator prototypes with optimal coverage characteristics. Patients and methods. Development of Contour-Analysis Tool 2 (CAT-2) software for TDM generation was the core priority of our task group. Main requests regarding software functionalities were formulated and guided the coding process. Software validation and accuracy check was performed using phantom objects. Concepts and terms for standardized workflow of TDM post-processing and applicator development were introduced. Results. CAT-2 enables applicator-based co-registration of Digital Imaging and Communications in Medicine (DICOM) structures from a sample of cases, generating a TDM with pooled contours in applicator-eye-view. Each TDM voxel is assigned a value, corresponding to the number of target contours encompassing that voxel. Values are converted to grey levels and transformed to DICOM image, which is transported to the treatment planning system. Iso-density contours (IDC) are generated as lines, connecting voxels with same grey levels. Residual Volume at Risk (RVR) is created for each IDC as potential volume that could contain organs at risk. Finally, standard and prototype applicators are applied on the TDM and virtual dose planning is performed. Dose volume histogram (DVH) parameters are recorded for individual IDC and RVR delineations and characteristic curves generated. Optimal applicator configuration is determined in an iterative manner based on comparison of characteristic curves, virtual implant complexities and isodose distributions. Conclusions. Using the TDM approach, virtual applicator prototypes capable of conformal coverage of any target volume, can be modelled. Further systematic assessment, including studies on clinical feasibility, safety and effectiveness are needed before routine use of novel prototypes can be considered.
Keywords: cervical cancer, brachytherapy, applicators, virtual modelling
Published in DiRROS: 09.05.2024; Views: 89; Downloads: 31
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Excellent outcomes after radiotherapy alone for malignant spinal cord compression from myeloma
Dirk Rades, Antonio J. Conde-Moreno, Jon Cacicedo, Barbara Šegedin, Volker Rudat, Steven E. Schild, 2016, original scientific article

Abstract: Uncertainty exists whether patients with spinal cord compression (SCC) from a highly radiosensitive tumor require decompressive spinal surgery in addition to radiotherapy (RT). This study addressed the question by evaluating patients receiving RT alone for SCC from myeloma. Patients and methods. Data of 238 patients were retrospectively analyzed for response to RT and local control of SCC. In addition, the effect of RT on motor function (improvement, no further progression, deterioration) was evaluated. Overall response was defined as improvement or no further progression of motor dysfunction. Prior to RT, patients were presented to a neurosurgeon for evaluation whether upfront decompressive surgery was indicated (e.g. vertebral fracture or unstable spine). Results. In the entire cohort, the overall response rate was 97% (53% improvement plus 44% no further progression). Following RT, 88% of the patients were able to walk. Of the 69 non-ambulatory patients 44 patients (64%) regained the ability to walk. Local control rates at 1, 2 and 3 years were 93%, 82% and 82%, respectively. A trend towards better local control was observed for patients who were ambulatory before starting RT (p = 0.08) and those with a more favorable performance status (p = 0.07). Conclusions. RT alone provided excellent response rates, functional outcomes and local control in patients with SCC from myeloma. These results should be confirmed in a prospective randomized trial.
Keywords: myeloma, spinal cord compression, radiotherapy
Published in DiRROS: 30.04.2024; Views: 176; Downloads: 79
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Uncertainties in target volume delineation in radiotherapy : are they relevant and what can we do about them?
Barbara Šegedin, Primož Petrič, 2016, original scientific article

Abstract: Modern radiotherapy techniques enable delivery of high doses to the target volume without escalating dose to organs at risk, offering the possibility of better local control while preserving good quality of life. Uncertainties in target volume delineation have been demonstrated for most tumour sites, and various studies indicate that inconsistencies in target volume delineation may be larger than errors in all other steps of the treatment planning and delivery process. The aim of this paper is to summarize the degree of delineation uncertainties for different tumour sites reported in the literature and review the effect of strategies to minimize them. Conclusions. Our review confirmed that interobserver variability in target volume contouring represents the largest uncertainty in the process for most tumour sites, potentially resulting in a systematic error in dose delivery, which could influence local control in individual patients. For most tumour sites the optimal combination of imaging modalities for target delineation still needs to be determined. Strict use of delineation guidelines and protocols is advisable both in every day clinical practice and in clinical studies to diminish interobserver variability. Continuing medical education of radiation oncologists cannot be overemphasized, intensive formal training on interpretation of sectional imaging should be included in the program for radiation oncology residents.
Keywords: target volume, interobserver variability, delineation uncertainties, imaging
Published in DiRROS: 30.04.2024; Views: 333; Downloads: 335
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MRI-assisted cervix cancer brachytherapy pre-planning, based on application in paracervical anaesthesia : final report
Primož Petrič, Robert Hudej, Omar Hanuna, Primož Marolt, Barbara Šegedin, 2014, original scientific article

Abstract: Background. Optimal applicator insertion is a precondition for the success of cervix cancer brachytherapy (BT). We aimed to assess feasibility and efficacy of MRI-assisted pre-planning, based on applicator insertion in para-cervical anaesthesia (PCA). Patients and methods. Five days prior to BT, the pre-planning procedure was performed in 18 cervix cancer patients: tandem-ring applicator was inserted under PCA, pelvic MRI obtained and applicator removed. Procedure tolerability was assessed. High risk clinical target volume (HR CTV) and organs at risk were delineated on the pre-planning MRI, virtual needles placed at optimal positions, and dose planning performed. At BT, insertion was carried out in subarachnoidal anaesthesia according to pre-planned geometry. Pre-planned and actual treatment parameters were compared. Results. Pre-planning procedure was well tolerated. Median difference between the pre-planned and actual needle insertion depth and position were 2 (0%10) mm and 4 (0%30) degrees, respectively. The differences between the pre-planned and actual geometric and dosimetric parameters were statistically non-significant. All actual needles were positioned inside the HR CTV and outside the organs at risk (OAR). Conclusions. Our pre-planning approach is well tolerated and effective. Pre-planned geometry and dose distribution can be reproduced at BT.
Keywords: cervix cancer, pre-planning, image-guided brachytherapy
Published in DiRROS: 11.04.2024; Views: 166; Downloads: 65
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Uterine perforation - 5-year experience in 3-D image guided gynaecological brachytherapy at Institute of Oncology Ljubljana
Barbara Šegedin, Jasenka Gugić Kevo, Primož Petrič, 2013, original scientific article

Abstract: Background. Accurate applicator placement is a precondition for the success of gynaecological brachytherapy (BT). Unrecognized uterine perforation can lead to bleeding, infection, high doses to pelvic organs and underdosage of the target volume, resulting in acute morbidity, long-term complications and reduced chance of cure. We aimed to assess the incidence and clinical characteristics of our cases with uterine perforation, review their management and impact on the treatment course. Patinets and methods. In all patients, treated with utero-vaginal image guided BT for gynaecological cancer between January 2006 and December 2011, the CT/MR images with the applicator in place were reviewed. The incidence of uterine perforations was recorded. Clinical factors that may have predisposed to increased risk of perforation were recorded. Management of perforations and their impact on treatment course was assessed. Results. 219 patients (428 applications) were suitable for analysis. Uterine perforation was found in 13 (3.0%) applications in 10 (4.6%) patients. The most frequent perforation site was posterior uterine wall (n = 9), followed by anterior wall (n = 2) and fundus (n = 2). All cases were managed conservatively, without complications. Prophylactic antibiotics were administered in 8 cases. In 4 patients, abdominal and/or transrectal ultrasound (US) guidance was used on subsequent applications for applicator insertion; adequate applicator placement was achieved and treatment completed as planned in all cases. Conclusions. 3D imaging for BT planning enables accurate identification of uterine perforations. The incidence of perforations at our department is one of the lowest reported in the literature. US guidance of applicator insertion is useful and feasible, allowing to complete the planned treatment even in challenging cases.
Keywords: uterine perforation, brachytherapy, 3D imaging, ultrasound guidance
Published in DiRROS: 22.03.2024; Views: 123; Downloads: 38
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Blaž Grošelj, Barbara Šegedin, 2023, preface, editorial, afterword

Keywords: onkologija, radioterapija, hrbtenjača, maligna utesnitev hrbtenjače
Published in DiRROS: 12.12.2023; Views: 206; Downloads: 92
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Primer bolnika z maligno utesnitvijo hrbtenjače
Ana Šešek, Barbara Šegedin, 2023, published scientific conference contribution

Keywords: onkologija, radioterapija, hrbtenjača, maligna utesnitev hrbtenjače
Published in DiRROS: 12.12.2023; Views: 190; Downloads: 97
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1. Šola maligne utesnitve hrbtenjače : [strokovno srečanje]
2023, not set

Abstract: Izidi zdravljenja maligne utesnitve hrbtenjače (MUH) v Sloveniji trenutno niso najboljši. Obravnava bolnikov je kompleksna, multidisciplinarna in večnivojska. Takoj ko bolnik zazna znake MUH, mora stanje prepoznati zdravnik družinske medicine, hitro ukrepati ter ga napotiti na nevrološki pregled oziroma k lečečemu onkologu. Namen 1. Šole maligne utesnitve hrbtenjače je, da se zdravniki, ki sodelujemo pri prepoznavi in zdravljenju MUH pogovorimo o trenutnem stanju obravnave in vseh dilemah, ki jih imamo.
Keywords: maligna utesnitev
Published in DiRROS: 29.11.2023; Views: 330; Downloads: 149
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