Katalin Hideghety - Academia.edu (original) (raw)
Papers by Katalin Hideghety
Journal of Nuclear Medicine & Radiation Therapy, 2018
Introduction: Aim of the current study was to compare gross tumour volume delineation for radiati... more Introduction: Aim of the current study was to compare gross tumour volume delineation for radiation therapy planning by PET/CT and CT scan in head and neck tumour patients. Methods: 70 oncological patients with primary head and neck cancer were enrolled in the study. CT and 18 F-FDG-PET/CT scans were performed within 3 weeks of enrolment in the planned irradiation position. For radiation therapy planning delineation of the target volumes was performed manually both in conventional topometric CT slides and in FDG-PET/CT images. Gross tumour target volume was calculated (GTVcm 3) using both modalities. Numerical and geometrical (intersection divided union ratio) comparisons were assessed. Intraobserver, interobserver, and intermodality variation analyses were performed. Results: Intra-and interobserver agreement (intraclass correlation coefficients: 0.99 and 0.97) of tumour volume delineation with 18 F-FDG-PET/CT was excellent. Radiotherapy target volume as assessed by FDG-PET/ CT differed in 98% (69/70) from target volumes calculated by the CT scans. According to the metabolic information, the target volume was larger in 12 cases (18%) and smaller in 58 cases (82%). Significant differences were found between CT and PET/CT based tumour volume (paired t-test, p<0.0001). Intersection divided union ratio showed low overlap (0.32). Conclusions: Tumour delineation for radiation therapy planning with PET/CT shows good reproducibility in patients with head and neck cancer. CT based morphologic information compared to PET/CT overestimates the tumour volume in larger lesions and may underestimate it in smaller target lesions. Differences are not only evident in tumour volume, but in geometry: Morphology of tumour volume and position. Integrated 18 F-FDG PET/CT imaging with combined morphological and metabolic information has the potential of improving radiotherapy planning, gross tumour volume (GTV) delineation. However there is currently no consensus on methods of delineation, volume definition or in regards to overall utility of 18 F-FDG-PET/CT scans in radiotherapy planning of in head and neck cancer patients. This field remains an active area of research [11]. The present work aims to study the reproducibility of tumour volume determination by 18 F-FDG-PET/ CT, and to compare it to the current standard contouring by CT scan in head and neck cancer patients. Patients and Methods We enrolled 70 patients undergoing radiation therapy planning for head and neck cancer (Group 1) in the current study. The average age of the patients was 58 ± 9 years (19-77 years). 20% of the studied patients (14/70) were women and 80% (56/70) were men. Histological distribution was the following: (94.3%; 66/70 patients) squamous
Proceedings of SPIE, May 16, 2017
The planned laser-driven ionizing beams (photon, very high energy electron, proton, carbon ion) a... more The planned laser-driven ionizing beams (photon, very high energy electron, proton, carbon ion) at laser facilities have the unique property of ultra-high dose rate (>Gy/s-10), short pulses, and at ELI-ALPS high repetition rate, carry the potential to develop novel laser-driven methods towards compact hospital-based clinical application. The enhanced flexibility in particle and energy selection, the high spatial and time resolution and extreme dose rate could be highly beneficial in radiotherapy. These approaches may increase significantly the therapeutic index over the currently available advanced radiation oncology methods. We highlight two nuclear reactionbased binary modalities and the planned radiobiology research. Boron Neutron Capture Therapy is an advanced cell targeted modality requiring 10 B enriched boron carrier and appropriate neutron beam. The development of laser-based thermal and epithermal neutron source with as high as 10 10 fluence rate could enhance the research activity in this promising field. Boron-Proton Fusion reaction is as well as a binary approach, where 11 B containing compounds are accumulated into the cells, and the tumour selectively irradiated with protons. Due to additional high linear energy transfer alpha particle release of the BPFR and the maximum point of the Bragg-peak is increased, which result in significant biological effect enhancement. Research at ELI-ALPS on detection of biological effect differences of modified or different quality radiation will be presented using recently developed zebrafish embryo and rodent models.
Radiotherapy and Oncology, Apr 1, 2018
Bevezetés: Az 18F-FDG-PET/CT vizsgálatoknak nem csupán a daganatok pontos stádiummeghatározá sába... more Bevezetés: Az 18F-FDG-PET/CT vizsgálatoknak nem csupán a daganatok pontos stádiummeghatározá sában van jelentősége, hanem egyre fontosabb szerepet tölt be a besugárzás tervezésében is. A jelen vizsgálatban a szerzők a besugárzástervezéshez készült natív CT, valamint az 18F-FDG-PET/CT vizsgálat alapján meghatározott tumortérfogatokat hasonlították össze fej-nyak tumoros betegekben, illetve vizs gálták a módszer reprodukálhatóságát. Betegek és módszerek: Hetven fej-nyak tumoros beteget vizsgáltunk. Minden esetben a későbbi be sugárzási pozícióban CT-, illetve FDG-PET/CT vizsgálat készült 3 héten belül. További 16 beteg képein 3 független szakember 20 különböző méretű szolid tumor kontúrozását végezte el az 18F-FDG-PET/CT felvételek alapján. A kapott eredményekből az alkalmazott manuális kijelölés intra-és interobserver va riabilitását határoztuk meg. A besugárzástervezéshez mind a hagyományos CT-alapú topometriás sze leteken, mind az FDG-PET/CT felvételeken elvégeztük a céltérfogatok manuális kontúrozását, és megha tároztuk a tumortérfogatot (GTV-cm3) mindkét modalitás alapján. A meghatározott tumortérfogatokat, illetve azok eltéréseit nem csupán abszolút értékben, hanem geometriai egyezés szempontjából is öszszehasonlítottuk. Eredmények: A módszer intra-és az interobserver variabilitása az egyes megfigyelők kontúrozása kö zött nem mutatott szignifikáns eltérést (intraklasz korrelációs koefficiens: 0,99 és 0,97). Összességében az FDG-PET/CT vizsgálat alapján meghatározott besugárzási céltérfogat az esetek 98%-ában (69/70) kü lönbözött a CT alapján megjelölt térfogattól. Tizenkettő esetben (16%) a tumortérfogat a metabolikus in formációk alapján nagyobb, 58 esetben (84%) kisebb lett. A két módszer alapján meghatározott céltér fogatok szignifikáns különbséget mutattak (kétmintás t-próba, p<0,0001). Megbeszélés: Az eredményeink alapján a kisebb térfogatú tumorok esetében a CT-vizsgálat alulbecsül heti, nagyobb tumorok esetében túlbecsülheti a tum or céltérfogatát. A geometriai összehasonlítás so rán a tumortérfogatelemek geometriája nagy variabilitást mutatott. Az FDG-PET/CT vizsgálat eredménye az esetek jelentős részében módosítja a tumortérfogatot, mely alapja a valós besugárzási mezőnek, ez által segítségünkre lehet a viabilis tumorszövet pontosabb meghatározásában, a rizikószervek dózister helésének csökkentésében. Vizsgálataink alapján megállapítható, hogy a CT-és az FDG-PET vizsgálat a tumorok két különböző tulajdonságát mutatja, és ezek az információk együttesen szükségesek a megfe lelő terápiás terv elkészítéséhez. Kulcsszavak: FDG-PET/CT, fej-nyak tumor, besugárzástervezés
Springer eBooks, 2001
Different parts of the patient body are exposed indirectly during BNCT treatment of glioblastoma ... more Different parts of the patient body are exposed indirectly during BNCT treatment of glioblastoma multiforme, depending on the geometrical alignment of the patient to the beam. Successful clinical application requires applicable solutions for the shielding of the organs at risk. At present during the irradiation, there is no way to measure the dose components in vivo in other parts of the body apart from the surface.
PubMed, Nov 1, 2011
The goal of this paper was to investigate the influence of FDG-PET/CT scan on the modification of... more The goal of this paper was to investigate the influence of FDG-PET/CT scan on the modification of staging and irradiation planning in patients suffering from non-small cell lung cancer (NSCLC). Fifteen patients suffering from NSCLC were analyzed by the authors from January, 2008 to July, 2009. The aim of the analysis was to examine the influence of FDG-PET/CT on irradiation planning and on decision-making of the complex oncologic therapy. The FDG-PET/CT scan was carried out in the position of irradiation performed later. For irradiation planning, planning target volumes (PTV) and the organs of risk were contoured on the patients' topometric CT slides as well as on the fused FDG-PET/CT slides. We evaluated how the application of PET/CT modified the stage of the illness, the complex oncologic therapeutic plan, the volume and the localization of the PTV, and the irradiation doses of the organs at risk. The mean and maximum dose of the spinal cord, the mean and V20 dose load of the lungs and the mean dose loads of the heart as well as of the left ventricle were measured. In 8 of 15 cases the stage of the disease and the treatment strategy was modified, since distant metastases were detected by the PET/CT. We evaluated the modification of the PTV and dose load of the organs at risk in 7 cases. According to the PET/CT the PTV was reduced in 5 cases (mean: 393.6 cm3) and was increased in 2 cases (mean: 250.8 cm3). Concerning the risk organs we found that the average (8.8 Gy/9.5 Gy) and maximum (33.4 Gy/36.4 Gy) dose load of the spinal cord increased, while the average (24.5 Gy/13.8 Gy) and V20 (33.7%/22.1%) dose load of the lungs decreased. We likewise found a decrease in the mean dose load of the heart (17.3 Gy/16.8 Gy) and left ventricle (12.9 Gy/9.6 Gy). In the majority of the cases the FDG-PET/CT scan modified the therapeutic decision, the size of the irradiated volume, and the dose load of the lung, the organ at risk causing the most difficulties at irradiation planning, was also reduced. The PET/CT scan plays an essential role in the complex oncologic treatment and irradiation therapy of NSCLC.
PubMed, Mar 22, 1998
The boron neutron capture therapy is based on the reaction occurring with certain probability, if... more The boron neutron capture therapy is based on the reaction occurring with certain probability, if a thermal neutron meets the boron 10 isotope. The low energy slow neutron is captured by the nucleus and it disintegrates into Li-nucleus and He-nucleus (alpha particle). If this physical reaction occurs in a living cell that will be destroyed. If the boron neutron capture reaction could be achieved selectively in malignant cells of tumor patients, that could be an effective therapeutical modality to treat the locally growing cancers. For boron neutron capture therapy to be successful two basic conditions must be fulfilled, an appropriate neutron source must be available and the sufficient number of 10B must be delivered possibly selectively into the tumor cells by a boron compound. At present both part of this binary system are under intensive investigation, the development of the neutron source, the synthetisation and experimental testing of boron delivery agents. The development of the dosimetry, microdosimetry, the work out of the powerful tools of detection the cellular, subcellular 10B distribution, the continuous improvement of the planning system and the optimization of the boron neutron capture therapy are the main point of the research area on boron neutron capture therapy. Clinical studies and clinical application of boron neutron capture therapy are under way for the treatment of melanoma malignum and for brain tumors, with the two boron compound has been clinically tested up to now, in Japan, at two Centres in USA, and recently has been started in Europe. The authors give an overview about the principles of boron neutron capture therapy, about the result of the research on neutron sources and boron compounds, moreover about the possible application area of this new radiation modality.
Radiotherapy and Oncology, 2006
Peer reviewe
Radiation Physics and Chemistry, Sep 1, 2020
Radiation dosimetry plays important role in the reproducibility of radiobiology experiments, in t... more Radiation dosimetry plays important role in the reproducibility of radiobiology experiments, in the replicability of results, as well as in the successful and safe use of radiotherapy procedures. The consistency and accuracy of the applied dosimetry methods pre-define the outcomes of these applications. This paper presents a version of the well-known ferrous sulphate-benzoic acid-xylenol orange (FBX) chemical dosimeter with improved sensitivity, accuracy and precision. Sensitivity is increased due to a slight modification in composition and the preparation procedures. We use stock solutions for the preparation of the dosimeter solution, which consists of 1 mM ferrous sulphate and 16 mM benzoic acid with 0.25 mM xylenol orange added post-irradiation. The nonlinear response to the absorbed dose of this system is eliminated by the increased ferrous sulphate concentration, permitting the calculation of the absorbed dose by a linear relationship between the absorbed dose and the optical absorbance of the solution. The measured chemical yield of our dosimeter is mol J 9.08 10 / 6 for 6 MV photon beams and mol J 6.42 10 / 6 for 250 kVp x-rays. This is a 24% enhancement over the original FBX solution, which permits a finer dose resolution. The accuracy and precision of our method is assured by a welldesigned and consistently used practice. A custom designed multipurpose PMMA slab phantom was used for irradiation in reference conditions. This phantom can be used for irradiation in reference conditions of dosimetric solutions, dosimetric films and chemical or biological samples. The combined standard uncertainty of this system is 1.12%, which can be improved by using an appropriate temperature correction factor. Furthermore, a working protocol has been established which allows dosimetry measurements using less than 1 mL dosimetric solutions.
Statistics in Medicine, Nov 9, 2001
Classical designs for clinical phase I trials assume that information about a dose‐limiting event... more Classical designs for clinical phase I trials assume that information about a dose‐limiting event (DLE) is available for all the included patients, or advise not to treat new patients until the information is present. If a DLE occurs after a lag, however, information at the current time might not be sufficient to make clear‐cut decisions according to these designs. In particular, if new patients are available, it is not clear whether to include them in the trial. We suggest a rule that decides on the accrual of each individual eligible patient. Simulation studies are presented that indicate an advantage over the standard ‘three‐at‐once’ design in the length of the study. Copyright © 2001 John Wiley & Sons, Ltd.
Radiotherapy and Oncology, Oct 1, 2019
Background and purpose: Motivated by first animal trials showing the normal tissue protecting eff... more Background and purpose: Motivated by first animal trials showing the normal tissue protecting effect of electron and photon Flash irradiation, i.e. at mean dose rates of 100 Gy/s and higher, relative to conventional beam delivery over minutes the feasibility of proton Flash should be assessed. Materials and methods: A setup and beam parameter settings for the treatment of zebrafish embryo with proton Flash and proton beams of conventional dose rate were established at the University Proton Therapy Dresden. Zebrafish embryos were treated with graded doses and the differential effect on embryonic survival and the induction of morphological malformations was followed for up to four days after irradiation. Results: Beam parameters for the realization of proton Flash were set and tested with respect to controlled dose delivery to biological samples. Analyzing the dose dependent embryonic survival and the rate of spinal curvature as one type of developmental abnormality, no significant influence of proton dose rate was revealed. For the rate of pericardial edema as acute radiation effect, a significant difference (p < 0.05) between proton Flash and protons delivered at conventional dose rate of 5 Gy/min was observed for one dose point only. Conclusion: The feasibility of Flash proton irradiation was successfully shown, whereas more experiments are required to confirm the presence or absence of a protecting effect and to figure out the limits and requirements for the Flash effect.
Radiotherapy and Oncology, Aug 1, 2009
The size of PTV1 ranged from 430-2320cm 3 for the included patients, PTV2 was on average 60±14% s... more The size of PTV1 ranged from 430-2320cm 3 for the included patients, PTV2 was on average 60±14% smaller. The highest conformity index was achieved for IMPT plans (0.84±0.04) compared to 2F (0.48±0.11) and IMRT (0.72±0.04) for both target volumes. The maximum doses to PTV and OARs did not differ for the compared treatment techniques. D1% (i.e. dose in most exposed 1% of volume) for PTV1 and PTV2 was in the same range and did not exceed 109% of the prescribed dose. Highest D1% for the lungs were 103% and 88% for plans with respect to PTV1 and PTV2, and 94% and 63% for the heart. For PTV1, IMPT compared to 2F resulted in a 40-70% reduction of the mean dose to OARs (lungs, heart). For PTV2 the mean dose reduction was less pronounced, since the total irradiated volume was smaller. Compared to 2F plans, IMRT was able to reduce OAR volumes receiving 80% (V80%) of the prescribed dose. Depending on target size and location, this reduction varied and was on average 30%. However, with IMRT the low dose region increased, especially for PTV1. For the smaller PTV2, V80% of lungs and heart was on average reduced by 45% and 40% for 2F compared to 2F plans for PTV1, by 40% and 60% for IMXT and by 17% and 30% for IMPT. Similar values were obtained for V60%. Comparing IMPT with both photon techniques, V80% for lungs and heart were on average decreased by about 80% and 55% for PTV1 and by 60% and 40% for PTV2. Conclusions: Traditionally used target concepts should be carefully revised in the light of new imaging modalities in order to optimize treatments for paediatric Hodgkin disease. Proton beam therapy has a high potential to further improve radiotherapy in paediatric radiation oncology.
Radiotherapy and Oncology, Apr 1, 2015
Purpose/Objective: Graves' Ophthalmopathy is the commonest extrathryoidal manifestation of Graves... more Purpose/Objective: Graves' Ophthalmopathy is the commonest extrathryoidal manifestation of Graves' disease. The underlying pathogenesis is believed to be autoimmunerelated leading to excessive infiltration of lymphocytes and excessive production of hydrophilic glycosaminoglycans and subsequently expansion of retro-orbital tissues and enlargement of extraocular muscles. Treatment options include steroid therapy, corrective/decompressive surgery, radiation therapy or combination of these approaches. Our purpose is to investigate if retro-orbital irradiation with Inverse VMAT IMRT planning produced better target coverage and dose sparing to adjacent normal structures as compared with Forward IMRT and 3D conformal for patients with bilateral Graves' Ophthalmopathy. Materials and Methods: Fourteen consecutive patients diagnosed with bilateral Graves' Ophthalmopathy were prospectively recruited into this study. An individual Inverse VMAT IMRT planning, Forward IMRT and 3D conformal plan was created for each patient. Conformity Index (CI), Homogeneity Index (HI) and other dosimetric parameters of the targets and organs-at-risk (OAR) were compared between the different techniques. Statistical analysis was T-student. Results: CI generated by Inverse VMAT IMRT planning was superior to that produced by Forward IMRT and 3D conformal (p<.001 for both respectively). As expected Forward IMRT was superior to 3D conformal (p=.007). However the differences in the HI was not significant. Inverse VMAT IMRT planning resulted in better OARs dose sparing (globe, lens, retina, lacrimal gland, optic nerve) with the exception of the optic chiasm that received a higher dose. The differences in the dose sparing of the OARs didn't shown a significant difference when comparing Forward IMRT to 3D conformal. Conclusions: Inverse VMAT IMRT planning is superior to Forward IMRT and 3D conformal for bilateral Graves' Ophthalmopathy treatment in virtue of the benefit on the target coverage, better CI with similar HI, and better sparing of the OARs, despite an increase in treatment planning and delivery time, consumption of monitor units and a slightly increased but clinically negligible dose to some surrounding structures.
Journal of Nuclear Medicine & Radiation Therapy, 2018
Introduction: Aim of the current study was to compare gross tumour volume delineation for radiati... more Introduction: Aim of the current study was to compare gross tumour volume delineation for radiation therapy planning by PET/CT and CT scan in head and neck tumour patients. Methods: 70 oncological patients with primary head and neck cancer were enrolled in the study. CT and 18 F-FDG-PET/CT scans were performed within 3 weeks of enrolment in the planned irradiation position. For radiation therapy planning delineation of the target volumes was performed manually both in conventional topometric CT slides and in FDG-PET/CT images. Gross tumour target volume was calculated (GTVcm 3) using both modalities. Numerical and geometrical (intersection divided union ratio) comparisons were assessed. Intraobserver, interobserver, and intermodality variation analyses were performed. Results: Intra-and interobserver agreement (intraclass correlation coefficients: 0.99 and 0.97) of tumour volume delineation with 18 F-FDG-PET/CT was excellent. Radiotherapy target volume as assessed by FDG-PET/ CT differed in 98% (69/70) from target volumes calculated by the CT scans. According to the metabolic information, the target volume was larger in 12 cases (18%) and smaller in 58 cases (82%). Significant differences were found between CT and PET/CT based tumour volume (paired t-test, p<0.0001). Intersection divided union ratio showed low overlap (0.32). Conclusions: Tumour delineation for radiation therapy planning with PET/CT shows good reproducibility in patients with head and neck cancer. CT based morphologic information compared to PET/CT overestimates the tumour volume in larger lesions and may underestimate it in smaller target lesions. Differences are not only evident in tumour volume, but in geometry: Morphology of tumour volume and position. Integrated 18 F-FDG PET/CT imaging with combined morphological and metabolic information has the potential of improving radiotherapy planning, gross tumour volume (GTV) delineation. However there is currently no consensus on methods of delineation, volume definition or in regards to overall utility of 18 F-FDG-PET/CT scans in radiotherapy planning of in head and neck cancer patients. This field remains an active area of research [11]. The present work aims to study the reproducibility of tumour volume determination by 18 F-FDG-PET/ CT, and to compare it to the current standard contouring by CT scan in head and neck cancer patients. Patients and Methods We enrolled 70 patients undergoing radiation therapy planning for head and neck cancer (Group 1) in the current study. The average age of the patients was 58 ± 9 years (19-77 years). 20% of the studied patients (14/70) were women and 80% (56/70) were men. Histological distribution was the following: (94.3%; 66/70 patients) squamous
Proceedings of SPIE, May 16, 2017
The planned laser-driven ionizing beams (photon, very high energy electron, proton, carbon ion) a... more The planned laser-driven ionizing beams (photon, very high energy electron, proton, carbon ion) at laser facilities have the unique property of ultra-high dose rate (>Gy/s-10), short pulses, and at ELI-ALPS high repetition rate, carry the potential to develop novel laser-driven methods towards compact hospital-based clinical application. The enhanced flexibility in particle and energy selection, the high spatial and time resolution and extreme dose rate could be highly beneficial in radiotherapy. These approaches may increase significantly the therapeutic index over the currently available advanced radiation oncology methods. We highlight two nuclear reactionbased binary modalities and the planned radiobiology research. Boron Neutron Capture Therapy is an advanced cell targeted modality requiring 10 B enriched boron carrier and appropriate neutron beam. The development of laser-based thermal and epithermal neutron source with as high as 10 10 fluence rate could enhance the research activity in this promising field. Boron-Proton Fusion reaction is as well as a binary approach, where 11 B containing compounds are accumulated into the cells, and the tumour selectively irradiated with protons. Due to additional high linear energy transfer alpha particle release of the BPFR and the maximum point of the Bragg-peak is increased, which result in significant biological effect enhancement. Research at ELI-ALPS on detection of biological effect differences of modified or different quality radiation will be presented using recently developed zebrafish embryo and rodent models.
Radiotherapy and Oncology, Apr 1, 2018
Bevezetés: Az 18F-FDG-PET/CT vizsgálatoknak nem csupán a daganatok pontos stádiummeghatározá sába... more Bevezetés: Az 18F-FDG-PET/CT vizsgálatoknak nem csupán a daganatok pontos stádiummeghatározá sában van jelentősége, hanem egyre fontosabb szerepet tölt be a besugárzás tervezésében is. A jelen vizsgálatban a szerzők a besugárzástervezéshez készült natív CT, valamint az 18F-FDG-PET/CT vizsgálat alapján meghatározott tumortérfogatokat hasonlították össze fej-nyak tumoros betegekben, illetve vizs gálták a módszer reprodukálhatóságát. Betegek és módszerek: Hetven fej-nyak tumoros beteget vizsgáltunk. Minden esetben a későbbi be sugárzási pozícióban CT-, illetve FDG-PET/CT vizsgálat készült 3 héten belül. További 16 beteg képein 3 független szakember 20 különböző méretű szolid tumor kontúrozását végezte el az 18F-FDG-PET/CT felvételek alapján. A kapott eredményekből az alkalmazott manuális kijelölés intra-és interobserver va riabilitását határoztuk meg. A besugárzástervezéshez mind a hagyományos CT-alapú topometriás sze leteken, mind az FDG-PET/CT felvételeken elvégeztük a céltérfogatok manuális kontúrozását, és megha tároztuk a tumortérfogatot (GTV-cm3) mindkét modalitás alapján. A meghatározott tumortérfogatokat, illetve azok eltéréseit nem csupán abszolút értékben, hanem geometriai egyezés szempontjából is öszszehasonlítottuk. Eredmények: A módszer intra-és az interobserver variabilitása az egyes megfigyelők kontúrozása kö zött nem mutatott szignifikáns eltérést (intraklasz korrelációs koefficiens: 0,99 és 0,97). Összességében az FDG-PET/CT vizsgálat alapján meghatározott besugárzási céltérfogat az esetek 98%-ában (69/70) kü lönbözött a CT alapján megjelölt térfogattól. Tizenkettő esetben (16%) a tumortérfogat a metabolikus in formációk alapján nagyobb, 58 esetben (84%) kisebb lett. A két módszer alapján meghatározott céltér fogatok szignifikáns különbséget mutattak (kétmintás t-próba, p<0,0001). Megbeszélés: Az eredményeink alapján a kisebb térfogatú tumorok esetében a CT-vizsgálat alulbecsül heti, nagyobb tumorok esetében túlbecsülheti a tum or céltérfogatát. A geometriai összehasonlítás so rán a tumortérfogatelemek geometriája nagy variabilitást mutatott. Az FDG-PET/CT vizsgálat eredménye az esetek jelentős részében módosítja a tumortérfogatot, mely alapja a valós besugárzási mezőnek, ez által segítségünkre lehet a viabilis tumorszövet pontosabb meghatározásában, a rizikószervek dózister helésének csökkentésében. Vizsgálataink alapján megállapítható, hogy a CT-és az FDG-PET vizsgálat a tumorok két különböző tulajdonságát mutatja, és ezek az információk együttesen szükségesek a megfe lelő terápiás terv elkészítéséhez. Kulcsszavak: FDG-PET/CT, fej-nyak tumor, besugárzástervezés
Springer eBooks, 2001
Different parts of the patient body are exposed indirectly during BNCT treatment of glioblastoma ... more Different parts of the patient body are exposed indirectly during BNCT treatment of glioblastoma multiforme, depending on the geometrical alignment of the patient to the beam. Successful clinical application requires applicable solutions for the shielding of the organs at risk. At present during the irradiation, there is no way to measure the dose components in vivo in other parts of the body apart from the surface.
PubMed, Nov 1, 2011
The goal of this paper was to investigate the influence of FDG-PET/CT scan on the modification of... more The goal of this paper was to investigate the influence of FDG-PET/CT scan on the modification of staging and irradiation planning in patients suffering from non-small cell lung cancer (NSCLC). Fifteen patients suffering from NSCLC were analyzed by the authors from January, 2008 to July, 2009. The aim of the analysis was to examine the influence of FDG-PET/CT on irradiation planning and on decision-making of the complex oncologic therapy. The FDG-PET/CT scan was carried out in the position of irradiation performed later. For irradiation planning, planning target volumes (PTV) and the organs of risk were contoured on the patients' topometric CT slides as well as on the fused FDG-PET/CT slides. We evaluated how the application of PET/CT modified the stage of the illness, the complex oncologic therapeutic plan, the volume and the localization of the PTV, and the irradiation doses of the organs at risk. The mean and maximum dose of the spinal cord, the mean and V20 dose load of the lungs and the mean dose loads of the heart as well as of the left ventricle were measured. In 8 of 15 cases the stage of the disease and the treatment strategy was modified, since distant metastases were detected by the PET/CT. We evaluated the modification of the PTV and dose load of the organs at risk in 7 cases. According to the PET/CT the PTV was reduced in 5 cases (mean: 393.6 cm3) and was increased in 2 cases (mean: 250.8 cm3). Concerning the risk organs we found that the average (8.8 Gy/9.5 Gy) and maximum (33.4 Gy/36.4 Gy) dose load of the spinal cord increased, while the average (24.5 Gy/13.8 Gy) and V20 (33.7%/22.1%) dose load of the lungs decreased. We likewise found a decrease in the mean dose load of the heart (17.3 Gy/16.8 Gy) and left ventricle (12.9 Gy/9.6 Gy). In the majority of the cases the FDG-PET/CT scan modified the therapeutic decision, the size of the irradiated volume, and the dose load of the lung, the organ at risk causing the most difficulties at irradiation planning, was also reduced. The PET/CT scan plays an essential role in the complex oncologic treatment and irradiation therapy of NSCLC.
PubMed, Mar 22, 1998
The boron neutron capture therapy is based on the reaction occurring with certain probability, if... more The boron neutron capture therapy is based on the reaction occurring with certain probability, if a thermal neutron meets the boron 10 isotope. The low energy slow neutron is captured by the nucleus and it disintegrates into Li-nucleus and He-nucleus (alpha particle). If this physical reaction occurs in a living cell that will be destroyed. If the boron neutron capture reaction could be achieved selectively in malignant cells of tumor patients, that could be an effective therapeutical modality to treat the locally growing cancers. For boron neutron capture therapy to be successful two basic conditions must be fulfilled, an appropriate neutron source must be available and the sufficient number of 10B must be delivered possibly selectively into the tumor cells by a boron compound. At present both part of this binary system are under intensive investigation, the development of the neutron source, the synthetisation and experimental testing of boron delivery agents. The development of the dosimetry, microdosimetry, the work out of the powerful tools of detection the cellular, subcellular 10B distribution, the continuous improvement of the planning system and the optimization of the boron neutron capture therapy are the main point of the research area on boron neutron capture therapy. Clinical studies and clinical application of boron neutron capture therapy are under way for the treatment of melanoma malignum and for brain tumors, with the two boron compound has been clinically tested up to now, in Japan, at two Centres in USA, and recently has been started in Europe. The authors give an overview about the principles of boron neutron capture therapy, about the result of the research on neutron sources and boron compounds, moreover about the possible application area of this new radiation modality.
Radiotherapy and Oncology, 2006
Peer reviewe
Radiation Physics and Chemistry, Sep 1, 2020
Radiation dosimetry plays important role in the reproducibility of radiobiology experiments, in t... more Radiation dosimetry plays important role in the reproducibility of radiobiology experiments, in the replicability of results, as well as in the successful and safe use of radiotherapy procedures. The consistency and accuracy of the applied dosimetry methods pre-define the outcomes of these applications. This paper presents a version of the well-known ferrous sulphate-benzoic acid-xylenol orange (FBX) chemical dosimeter with improved sensitivity, accuracy and precision. Sensitivity is increased due to a slight modification in composition and the preparation procedures. We use stock solutions for the preparation of the dosimeter solution, which consists of 1 mM ferrous sulphate and 16 mM benzoic acid with 0.25 mM xylenol orange added post-irradiation. The nonlinear response to the absorbed dose of this system is eliminated by the increased ferrous sulphate concentration, permitting the calculation of the absorbed dose by a linear relationship between the absorbed dose and the optical absorbance of the solution. The measured chemical yield of our dosimeter is mol J 9.08 10 / 6 for 6 MV photon beams and mol J 6.42 10 / 6 for 250 kVp x-rays. This is a 24% enhancement over the original FBX solution, which permits a finer dose resolution. The accuracy and precision of our method is assured by a welldesigned and consistently used practice. A custom designed multipurpose PMMA slab phantom was used for irradiation in reference conditions. This phantom can be used for irradiation in reference conditions of dosimetric solutions, dosimetric films and chemical or biological samples. The combined standard uncertainty of this system is 1.12%, which can be improved by using an appropriate temperature correction factor. Furthermore, a working protocol has been established which allows dosimetry measurements using less than 1 mL dosimetric solutions.
Statistics in Medicine, Nov 9, 2001
Classical designs for clinical phase I trials assume that information about a dose‐limiting event... more Classical designs for clinical phase I trials assume that information about a dose‐limiting event (DLE) is available for all the included patients, or advise not to treat new patients until the information is present. If a DLE occurs after a lag, however, information at the current time might not be sufficient to make clear‐cut decisions according to these designs. In particular, if new patients are available, it is not clear whether to include them in the trial. We suggest a rule that decides on the accrual of each individual eligible patient. Simulation studies are presented that indicate an advantage over the standard ‘three‐at‐once’ design in the length of the study. Copyright © 2001 John Wiley & Sons, Ltd.
Radiotherapy and Oncology, Oct 1, 2019
Background and purpose: Motivated by first animal trials showing the normal tissue protecting eff... more Background and purpose: Motivated by first animal trials showing the normal tissue protecting effect of electron and photon Flash irradiation, i.e. at mean dose rates of 100 Gy/s and higher, relative to conventional beam delivery over minutes the feasibility of proton Flash should be assessed. Materials and methods: A setup and beam parameter settings for the treatment of zebrafish embryo with proton Flash and proton beams of conventional dose rate were established at the University Proton Therapy Dresden. Zebrafish embryos were treated with graded doses and the differential effect on embryonic survival and the induction of morphological malformations was followed for up to four days after irradiation. Results: Beam parameters for the realization of proton Flash were set and tested with respect to controlled dose delivery to biological samples. Analyzing the dose dependent embryonic survival and the rate of spinal curvature as one type of developmental abnormality, no significant influence of proton dose rate was revealed. For the rate of pericardial edema as acute radiation effect, a significant difference (p < 0.05) between proton Flash and protons delivered at conventional dose rate of 5 Gy/min was observed for one dose point only. Conclusion: The feasibility of Flash proton irradiation was successfully shown, whereas more experiments are required to confirm the presence or absence of a protecting effect and to figure out the limits and requirements for the Flash effect.
Radiotherapy and Oncology, Aug 1, 2009
The size of PTV1 ranged from 430-2320cm 3 for the included patients, PTV2 was on average 60±14% s... more The size of PTV1 ranged from 430-2320cm 3 for the included patients, PTV2 was on average 60±14% smaller. The highest conformity index was achieved for IMPT plans (0.84±0.04) compared to 2F (0.48±0.11) and IMRT (0.72±0.04) for both target volumes. The maximum doses to PTV and OARs did not differ for the compared treatment techniques. D1% (i.e. dose in most exposed 1% of volume) for PTV1 and PTV2 was in the same range and did not exceed 109% of the prescribed dose. Highest D1% for the lungs were 103% and 88% for plans with respect to PTV1 and PTV2, and 94% and 63% for the heart. For PTV1, IMPT compared to 2F resulted in a 40-70% reduction of the mean dose to OARs (lungs, heart). For PTV2 the mean dose reduction was less pronounced, since the total irradiated volume was smaller. Compared to 2F plans, IMRT was able to reduce OAR volumes receiving 80% (V80%) of the prescribed dose. Depending on target size and location, this reduction varied and was on average 30%. However, with IMRT the low dose region increased, especially for PTV1. For the smaller PTV2, V80% of lungs and heart was on average reduced by 45% and 40% for 2F compared to 2F plans for PTV1, by 40% and 60% for IMXT and by 17% and 30% for IMPT. Similar values were obtained for V60%. Comparing IMPT with both photon techniques, V80% for lungs and heart were on average decreased by about 80% and 55% for PTV1 and by 60% and 40% for PTV2. Conclusions: Traditionally used target concepts should be carefully revised in the light of new imaging modalities in order to optimize treatments for paediatric Hodgkin disease. Proton beam therapy has a high potential to further improve radiotherapy in paediatric radiation oncology.
Radiotherapy and Oncology, Apr 1, 2015
Purpose/Objective: Graves' Ophthalmopathy is the commonest extrathryoidal manifestation of Graves... more Purpose/Objective: Graves' Ophthalmopathy is the commonest extrathryoidal manifestation of Graves' disease. The underlying pathogenesis is believed to be autoimmunerelated leading to excessive infiltration of lymphocytes and excessive production of hydrophilic glycosaminoglycans and subsequently expansion of retro-orbital tissues and enlargement of extraocular muscles. Treatment options include steroid therapy, corrective/decompressive surgery, radiation therapy or combination of these approaches. Our purpose is to investigate if retro-orbital irradiation with Inverse VMAT IMRT planning produced better target coverage and dose sparing to adjacent normal structures as compared with Forward IMRT and 3D conformal for patients with bilateral Graves' Ophthalmopathy. Materials and Methods: Fourteen consecutive patients diagnosed with bilateral Graves' Ophthalmopathy were prospectively recruited into this study. An individual Inverse VMAT IMRT planning, Forward IMRT and 3D conformal plan was created for each patient. Conformity Index (CI), Homogeneity Index (HI) and other dosimetric parameters of the targets and organs-at-risk (OAR) were compared between the different techniques. Statistical analysis was T-student. Results: CI generated by Inverse VMAT IMRT planning was superior to that produced by Forward IMRT and 3D conformal (p<.001 for both respectively). As expected Forward IMRT was superior to 3D conformal (p=.007). However the differences in the HI was not significant. Inverse VMAT IMRT planning resulted in better OARs dose sparing (globe, lens, retina, lacrimal gland, optic nerve) with the exception of the optic chiasm that received a higher dose. The differences in the dose sparing of the OARs didn't shown a significant difference when comparing Forward IMRT to 3D conformal. Conclusions: Inverse VMAT IMRT planning is superior to Forward IMRT and 3D conformal for bilateral Graves' Ophthalmopathy treatment in virtue of the benefit on the target coverage, better CI with similar HI, and better sparing of the OARs, despite an increase in treatment planning and delivery time, consumption of monitor units and a slightly increased but clinically negligible dose to some surrounding structures.