Predictive value of PET/CT based metabolic information in the modern 3D based radiotherapy treatment of head and neck can-cer patients - single institute study.

OBJECTIVE: The aim of the study was to evaluate the predictive value of pretreatment positron emission tomography (PET) standardized uptake value (SUVmax), standardized uptake value corrected for lean body mass (SULpeak) value, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) parameters of the primary tumour assessed with PET/computed tomography (CT) in the clinical out-come in patients diagnosed with histopathologically confirmed head and neck squamous cell carcinoma. MATERIALS AND METHODS: Retrospective evaluation was performed using PET/CT image datasets of 52 histologically proven head and neck cancer patients in 4 weeks' prior receiving definitive chemo-radiotherapy (CRT). Positron emission tomography /CT was performed before the CRT and 12 weeks after it for response evaluation. Image data was used for target volume delineation and for specify SUVmax, SULpeak, MTV and TLG parameters of the primary tumour. According to the results of the therapeutic response evaluation two patient subgroups were created in relation to the presence or absence of viable tumour. Metabolic data from pre-treatment PET/CT and therapeutic response were correlated using Kruskal-Wallis test. RESULTS: After completion of the CRT in 24/52 (46%) cases viable residual tumour was detected on restaging PET/CT, while in 28/52 (54%) patients showed complete remission. For the therapeutic success prediction assessment, we could not find any significant correlation with pre-treatment SUVmax and SULpeak values (P>0.44, P>0.33). Total lesion glycolysis provided nearly significant difference (P=0.052) and MTV had shown significant difference (P=0.001) between the two patient subgroups statistically. CONCLUSION: Simple metabolic data (SUVmax and SULpeak) from pretreatment fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT were unable to predict therapeutic response, while volumetric information containing MTV and TLG parameters proved to be more useful, thus their inclusion to risk stratification may also have additional value.

OAR sparing 3D radiotherapy planning supported by fMRI brain mapping investigations.

The human brain as an organ has numerous functions; some of them can be visualized by functional imaging techniques (e.g., functional MRI [fMRI] or positron emission tomography). The localization of the appropriate activity clusters requires sophisticated instrumentation and complex measuring protocol. As the inclusion of the activation pattern in modern self-tailored 3D based radiotherapy has notable advantages, this method is applied frequently. Unfortunately, no standardized method has been published yet for the integration of the fMRI data into the planning process and the detailed description of the individual applications is usually missing. Thirteen patients with brain tumors, receiving fMRI based RT planning were enrolled in this study. The delivered dose maps were exported from the treatment planning system and processed for further statistical analysis. Two parameters were introduced to measure the geometrical distance Hausdorff Distance (HD), and volumetric overlap Dice Similarity Coefficient (DSC) of fMRI corrected and not corrected dose matrices as calculated by 3D planning to characterize similarity and/or dissimilarity of these dose matrices. Statistical analysis of bootstrapped HD and DSC data was performed to determine confidence intervals of these parameters. The calculated confidence intervals for HD and DSC were (5.04, 7.09), (0.79, 0.86), respectively for the 40 Gy and (5.2, 7.85), (0.74, 0.83), respectively for the 60 Gy dose volumes. These data indicate that in the case of HD < 5.04 and/or DSC > 0.86, the 40 Gy dose volumes obtained with and without fMRI activation pattern do not show a significant difference (5% significance level). The same conditions for the 60 Gy dose volumes were HD < 5.2 and/or DSC > 0.83. At the same time, with HD > 7.09 and/or DSC < 0.79 for 40 Gy and HD > 7.85 and/or DSC < 0.74 for 60 Gy the impact of fMRI utilization in RT planning is excessive. The fMRI activation clusters can be used in daily RT planning routine to spare activation clusters as critical areas in the brain and avoid their high dose irradiation. Parameters HD (as distance) and DSC (as overlap) can be used to characterize the difference and similarity between the radiotherapy planning target volumes and indicate whether the fMRI delivered activation patterns and consequent fMRI corrected planning volumes are reliable or not.

[Possibilities of dose reduction during CT imaging by application of iterative image reconstruction]. / A dóziscsökkentés lehetoségei CT-képalkotás során az iteratív képrekonstrukció alkalmazásával.

Introduction and aim: In case of imaging modalities using ionizing radiation, radiation exposure of the patients is a vital issue. It is important to survey the various dose-reducing techniques to achieve optimal radiation protection while keeping image quality on an optimal level. Method: We reprocessed 105 patients' data prospectively between February and April 2017. The determination of the radiation dose was based on the effective dose, calculated by multiplying the dose-length product (DLP) and dose-conversation coefficient. In case of image quality we used signal-to-noise ratio (SNR) based on manual segmentation of region of interest (ROI). For statistical analysis, one sample t-test and Wilcoxon signed rank test were used. Results: Using iterative reconstruction, the effective dose was significantly lower (p<0.001) in both native and contrast-enhanced abdominal, contrast-enhanced chest CT scans and in the case of the total effective dose. At native and contrast-enhanced abdominal CT scans, the noise content of the images showed significantly lower (p<0.001) values for iterative reconstruction images. At contrast-enhanced chest CT scans there was no significant difference between the noise content of the images (p>0.05). Conclusion: Using iterative reconstruction, it was possible to achieve significant dose reduction. Since the noise content of the images was not significantly higher using the iterative reconstruction compared to the filtered back projection, further dose reduction can be achievable while preserving the optimal quality of the images. Orv Hetil. 2019; 160(35): 1387-1394.

[Multimodal imaging during lung and abdominal stereotactic ablative radiotherapy: from cine MRI through 3D/4D CBCT to intrafractional kV verification]. / Multimodális képalkotás tüdõ- és hasi sztereotaxiás ablatív radioterápia során: a cine MRI-mérésektõl a 3D/4D CBCT-n át a kezelés alatti kV-os képi verifikációig.

Our aim was to present our treatment and verification protocols of linear accelerator-based lung and abdominal stereotactic ablative radiotherapy (SABR). During our treatments both the volumetric imaging (3D/4D CBCT/CT) and triggered kV intrafractional tumor motion control could be combined allowing a full control on the whole workflow. The most optimal kV directions from which the tumor is well detectable were defined. Tumor movements measured on cine MRI in treatment position correlated well with the ones on 4D CBCT, thus cine MRI is considered an excellent device to pre-select the appropriate image/treatment verification SABR protocol. In abdominal targets implanted markers and cine MRI are preferred due to limited image quality of CBCT with the current version. In selected lung SABR cases (≥8mm motion) the dose delivery of organs at risk (lungs - GTV, chest wall) could be reduced compared to free breathing conditions, however, the treatment time is at least two-folds higher.

[F-DOPA PET/MR based target definiton in the 3D based radiotherapy treatment of glioblastoma multiforme patients. First Hungarian experiences]. / F-DOPA-jelzett PET/CT-PET/MR alapú modern 3D besugárzástervezés glioblastoma multiformés (GBM-) betegek komplex kezelésében. Az elso magyarországi tapasztalatok.

BACKGROUND AND PURPOSE: Radiotherapy plays important role in the complex oncological treatment of glioblastoma multiforme (GBM). The modern 3D radiotherapy treatments are based on cross-sectional CT and MR information, however more attention is being paid to functional hybrid imaging describing the biological and functional morphology of tumor lesions. 18F-DOPA is an amino acid tracer with high specificity and sensitivity, which may play an important role in the precise definition of target volume in the irradiation process of GBM patients. Our study presents the first experiences with 18F-DOPA based PET/CT/MR 3D irradiation planning process. METHODS: In Hungary the 18F-DOPA radiotracer has been available for clinical use since September 2017. Between September 2017 and January 2018, at the Somogy County Kaposi Mór Teaching Hospital Dr. József Baka Diagnostic, Radiation Oncology, Research and Teaching Center 3 histologically verified glioblastoma multiforme patients received 18F-DOPA based 3D irradiation treatment. In the contouring process the native planning CT scanes were fused with the PET/MR series (T1 contrast enhanced, T2 and 18F-DOPA sequences). We defined 18F-DOPA uptake volume (BTV-F-DOPA), the T1 contrast enhanced MRI volume (GTV-T1CE), and the volume of the area covered by oedema on the T2 weighted MRI scan (CTV-oedema) in all patients. We also registered the BTV-F-DOPA volumes not covered by the conventional MR based target volumes. RESULTS: Examining the 3 cases, the average volume of 18F-DOPA tumor was 22.7 cm3 (range 15.3-30.9; SD = 7.82). The average GTV T1 CE was found to be 8.7 cm3 (range 3.8-13.2; SD = 4.70). The mean CTV oedema volume was 40.3 cm3 (range 27.7-57.7; SD = 15.36). A non-overlapping target volume difference (BTV-F-DOPA not covered by CTV oedema area) was 4.5 cm3 (range 1-10.3; SD = 5.05) for PTV definition. CONCLUSION: Based on our results the tumor area defined by the amino acid tracer is not fully identical with the MRI defined T2 oedema CTV. 18F-DOPA defined BTV can modify the definiton of the PTV, and the radiotherapy treatment.

[The predictive role of PET/CT imaging in clinical N and M staging and treatment decision process. Institutional experiences in Hungary]. / A PET/CT szerepe a sugárkezelésre kerülo betegek N és M klinikai stagingjében, a terápia meghatározásában. Intézeti tapasztalatok.

INTRODUCTION AND AIM: The aim of our study was to investigate changes in clinical staging N (lymph node) and M (distant metastasis) in patients who receive PET/CT-based 3D radiotherapy within complex oncological treatment, and compare to conventional cross-sectional imaging staging technique. We also investigated the presence of PET/CT-detected second tumors and the effect of PET/CT on therapeutic decisions. METHOD: From the 1st of January 2015 to the 30th of November 2016, 192 patients (n = 192) were treated with PET/CT-based radiation (109 head, 44 lung, 28 rectum and 11 cervical localization) in the Oncoradiology Institute of the Health Center of the University of Kaposvár. All patients received conventional cross-sectional and PET/CT imaging in accordance with the valid investigation protocol. The average time interval between the two cross-sectional investigations was 5.2 weeks. Clinical N and M staging was performed on the basis of the classification of the American Joint Committee on Cancer (AJCC) and the Union of International Cancer Control (UICC). RESULTS: By analyzing the clinical stages N and M separately, based on the results of the PET/CT studies, the N stage was changed in 77 cases and the M stage changed in 31 cases. Overall, the PET/CT study resulted in higher clinical stages in 68 (35.4%) patients and lower clinical stages in 14 (7.3%) patients. The treatment plan was changed in 9% of the patients (n = 18) (definitive versus palliative treatment) and the extension of radiotherapy treatment target volume (PTV) was indicated in 20% of the patients (n = 39) due to the change in clinical lymph node status. PET/CT also detected secondary tumors in 15 (8%) patients. CONCLUSION: Based on our results, the addition of PET/CT to conventional cross-sectional staging imaging permits a more accurate clinical classification of N and M stages and significantly influences therapeutic decisions. PET/CT imaging also provides a great help in detecting occult second tumors. The results of our Institute harmonize with the international data available in the literature. Orv Hetil. 2018; 159(39): 1593-1601.

[Hungarian clinical application opportunities of PET/MR imaging and first experiences]. / A PET/MR képalkotás magyarországi klinikai alkalmazásának lehetoségei, elso tapasztalatai.

Hungary's first and still only multimodality PET/MR device is operating in the Health Center of Kaposvár University. The aim of our review article is to present the current Hungarian PET/MR imaging application opportunities, our available initial experiences with this novel multimodality imaging technique in malignant and non-malignant diseases and further potential targeted clinical fields of use are also addressed. Orv Hetil. 2018; 159(34): 1375-1384.

[Setup margin for head-and-neck cancer patients receiving 2D-2D and 3D image-guided intensity-modulated radiation therapy]. / A beállítási biztonsági margó nagyságának meghatározása fej-nyak daganatok 2D-2D és 3D képvezérelt intenzitásmodulált sugárkezelése esetén.

INTRODUCTION: Image-guided intensity-modulated radiation therapy is essential for oncology treatment of head-and-neck cancer patients. AIM: MV-kV and CBCT modalities were compared in case of IGRT treatment for head-and-neck cancer patients. Setup error, setup margin (SM), imaging and evaluation times and imaging doses were analyzed. METHOD: Eight patients' elective treatment was evaluated, 66 orthogonal MV-kV images and 66 CBCT series were acquired. Setup error measurement was based on bony manual image registration in three translational directions. Normality test and F-test were performed followed by the comparison with independent-samples T-test (p<0,05). The necessary target volume setup margin was calculated based on Van Herk's equation. Imaging time and setup error determination time were measured. Imaging doses were estimated based on the literature. RESULTS: No statistically significant difference was found between setup errors determined by MV-kV and CBCT (VRT: 0.5 mm, SD = 1.9 vs. 0.4 mm, SD = 2.1, p = 0.371; LNG: 0.2 mm, SD = 2.2 vs. -0.1 mm, SD = 2.2, p = 0.188; LAT: 0.2 mm, SD = 2.2 vs. 0.3 mm, SD = 2.1, p = 0.41). SM values were: VRT: 2.7 mm vs. 2.5 mm; LNG: 2.1 mm vs. 1.3 mm; LAT: 2.2 mm vs. 2.3 mm. Mean imaging time was 0.65 min (MV-kV) vs. 2.29 min (CBCT). Mean setup error determination time was 2.41 min for both modalities. Estimated imaging doses were 6.88 mGy (MV-kV) vs. 17.2 mGy (CBCT) per fraction. CONCLUSION: The bony anatomy derived image registration based translational setup error determination results in similar values either by MV-kV or by CBCT. Using 3 mm setup margin in all the directions might be adequate. Imaging time is less by MV-kV, significant difference in imaging doses did not appear. Using CBCT is generally suggested. MV-kV might be an alternative in case of need for shortened imaging time. Orv Hetil. 2018; 159(29): 1193-1200.

Long-term follow-up results of concomitant chemoradiotherapy followed by adjuvant temozolomide therapy for glioblastoma multiforme patients. The importance of MRI information in survival: Single-center experience.

BACKGROUND AND PURPOSE: Glioblastoma multiforme (GBM) is the most common malignant primary anomaly of central nervous system. The GBM infiltrates the nearly sturctures from the initial tumor and its metastatic attribution is well known. The aim of our single-centered retrospective study was to introduce the importance of postoperative medical imaging confirmation of total tumor resection for patient with GBM combined concomitant and adjuvant chemoradiotherapy on a 10 year long patient follow up. METHODS: From January 2006 to April 2015 we registered 59 patients with newly diagnosed GBM at the University of Kaposvár Health Center Institute of Diagnostic Imaging and Radiation Oncology. The histological diagnosis was confirmed by a proficient neuropathologist (World Health Organisation WHO; grade IV astrocytoma). According to histological status if the ECOG performance status of patients allowed it the mutidisciplinary oncoteam recommended adjuvant chemoradiotherapy all features strictly by Stupp protocol. (60 Gy dose on the gross tumor volume and 2-3 cm margin for the clinical target volume with parallel 75 mg/m2 TMZ. Four weeks after monotherapial phase patients had to recieve 6 cycles of TMZ first cycle with 150 mg/m2 up to 200 mg/m2). The irradiation was carried out by a conformal three dimensional planning system. RESULTS: 59 patients with the median age of 63 (range 17-84) year. Our sample counted 34 male patients and 25 woman patients. 14 patients underwent gross total tumor resection while, 39 patients underwent partial resection and the rest from our sample 6 patients passed through biopsy. Statistical analysis showed a lengthier survival among males than females, with a median survival of 13 months for males and females, the OS of 26.209 for males, meanwhile 15.625 for females. However, the difference is not considerable (log-rank p=0.203). Our study found that the estimated survival of patients at least 50 years old is significantly shorter at a median survival of 12 months (log rank p=0.027) than that of patients below 50 years of age at a median survival of 23 months. The longest estimated median survival was calculated with patients of ECOG '0' condition (16 months). However, no significant difference was found in the estimated survival of patients of different ECOG conditions (log-rank p=0.146). Based on the extent of surgery, complete resection resulted in the longest average survival of 36.4 months, followed by 21.5 months among patients with biopsy, and 15.8 months among patients with partial resection. Different surgical procedures, however, did not result in significant differences in survival (log-rank p=0.059). The overal survival of patients who had complete resection confirmed by MRI compared with the overal survival of patients with residual tumor confirmed by MRI as well we can estimate that there is significant difference between these two groups (p=0,004). CONCLUSION: Despite complex and intense treatment, recurrence is inevitable and causes relatively rapid death. In our analysis complete resection, as defined from the neurosurgeon's report and postoperative MRI, resulted in an independently significant improvement in OS. Our results are the evidences that the treatment of patients with glioblastoma multiforme in Hungary is at least on the same level as any other developed European countries.

[Interventional radiology and radiation therapy]. / Intervenciós radiológia és sugárterápia.

The revolutionary role of modern cross-sectional imaging, the improved target definition in CT/MRI image guided brachytherapy, the precise topography for applicator and anatomy contribute to a better knowledge and management of tumors and critical organs. Further developments and functional imaging is expected to lead to a broad use of patient tailored therapy in the field of interventional radiation oncology.

Integrating functional MRI information into conventional 3D radiotherapy planning of CNS tumors. Is it worth it?

The purpose of our study was to examine the potential benefits of integrating functional MRI (fMRI) information into the 3D-based planning process for central nervous system (CNS) malignancies. Between 01.01.2008 and 01.12.2009, ten patients with astrocytoma (both low and high-grade histological type) were enrolled in this study. Before the planning process, conventional CT planning, postoperative MR, and individual functional MRI examinations were conducted. For the functional MRI examination four types of conventional stimuli were applied: acoustic, visual, somatosensory, and numeric. To examine the potential benefits of using fMRI-based information, three different types of theoretical planning were applied and compared: 3D conformal plan without fMRI information, 3D conformal plan with fMRI information, and IMRT plan with fMRI information. DVH analysis and the NTCP model were used for plan comparison. When comparing planning methods, distance-related subgroups were generated and studied. By using the additional fMRI information, a significantly higher sparing effect can be achieved on these ORs (both with conventional 3D-based planning and IMRT). In cases when the OR-PTV distance is less than 1 cm, IMRT seems to be a significantly better choice than conventional 3D-based techniques. IMRT also has an additional sparing effect on the optic tract and brainstem, especially for locations close to the midline. Our results demonstrated that using fMRI information in conventional 3D-based treatment planning has the potential benefit of significant dose reduction for the critical organs, with no compromise in PTV coverage even when using conventional 3D planning. fMRI can be widely used in low-grade cases (long life expectancy, lower acute and late toxicity) and also in cases with high-grade astrocytomas or distant metastases (higher dose to PTV with better sparing of risk organs). In cases when the OR-PTV distance is less than 1 cm, IMRT should be the choice of treatment for a higher sparing effect on functional active areas. Longer imaging and clinical follow up are needed to confirm the real sparing effect on these functional areas.

Open MR-guided high-dose-rate (HDR) prostate brachytherapy: feasibility and initial experiences open MR-guided high-dose-rate (HDR) prostate brachytherapy.

The aim of our pilot study was to demonstrate the feasibility and dosimetric quality of MR-guided HDR prostate brachytherapy in a low-field 0.35T open MRI scanner and to present our initial clinical experiences. 16 patients with intermediate- to high-risk localized prostate cancer were treated with 46-60 Gy of external beam radiotherapy preceded and/or followed by an 8 Gy MR-guided HDR boost. For interventions an MR compatible custom-made system, coaxial needles and plastic catheters were used. Template reconstruction, trajectory planning, image guidance, contouring and treatment planning were exclusively based on MR images. For treatment planning, dose-point- and anatomy-based inverse planning optimization was used. Image quality was found to be good to excellent in almost all cases. The mean catheter placement accuracy modeled by Rayleigh distribution was 2.9 mm with a sigma value of 2.3 mm. The mean and standard deviation (SD) of the dosimetric results for the target volume were the following: V100: 94.2 ± 4.3%, V150: 43.9 ± 6.8%, V200: 18.5 ± 5.9%. The mean D(0.1), D(1) and D1 values for the intraprostatic urethra were 117.6 ± 12.5%, 98.5 ± 19.9% and 122.3 ± 16.4%, respectively. Regarding the rectal wall the mean D(0.1), D(1) and D(2) values were 77.3 ± 7.2%, 64.8 ± 7.5%, and 53.2 ± 9.1%, respectively. The mean maximum dose for the inner rectal surface was 53.5 ± 9.2%. No RTOG Grade 3 or worse acute toxicities were observed. Our method seems to be a promising approach for performing feasible, accurate and high-quality MR-guided HDR prostate brachytherapy. To determine the long term side effects and outcome higher number of patients, additional follow-up is needed.

Integrating functional MRI information into radiotherapy planning of CNS tumors-early experiences.

The purpose of our study was to examine the integration of functional MRI (fMRI) information into 3D based planning process of the central nervous system (CNS) malignancies. Between 01.01.2008 and 01.12.2008 four patients with astrocytoma were enrolled to this study. Before the planning process conventional planning CT, postoperative MR and individual functional MRI examinations were delivered. For the functional MRI examination the following four types of stimulus were applied: acoustic, visual, somatosensory and numeral. Three different theoretical planning situations were applied and compared: 3D conformal plan without fMRI information, 3D conformal plan with fMRI information and IMRT plan with fMRI information. For plan comparison DVH analysis, and NTCP model were used. fMRI based OR definition resulted in 4 additional OR's in the contouring process. As these cases demonstrate, an average of 50% dose reduction was achieved in OR, OR2 and OR3 with IMRT and fMRI based 3D planning, especially in case of midline localization and big tumor extent. IMRT provides additional sparing effect in the optic tract and brainstem, especially for localizations close to the midline. Our results demonstrated that using fMRI information in conventional 3D based treatment planning potentially benefits significant dose reduction in critical organs, with no compromise in PTV coverage. fMRI can be widely used even in low grade cases (long life expectancies, lower acute and late toxicity in radiotherapy) and in cases with high grade astrocytomas or metastases (higher dose to PTV with better risk organ sparing in radiotherapy).

3-D conformal photon boost in the treatment of early stage breast cancer: four year follow up results.

In the treatment of early stage breast cancer, breast conserving surgery (BCS) followed by whole breast irradiation (WBI) is the standard treatment. The impact of the tumor bed boost following WBI is well-defined, but there are various delivery methods. In this study we demonstrate our 4 year experience with the 3-D conformal boost technique. Between January 2004 and June 2005, 77 early stage (Stage I-II) breast cancer patients were treated in our institute with whole breast irradiation (WBI, 50.4 Gy in 28 fractions) after breast conserving surgery. Following WBI, 3-D conformal photon boost was delivered (10-16 Gy in five to eight fractions) for all patients. The clinical outcome was retrospectively recorded in terms of survival and local control. The side effect profile (fibrosis, fat necrosis and cosmetic outcome) was also recorded and studied. In our patient group the mean follow up time was 46.8 months (median: 52, range: 17-71, SD: 14.4) The 4-year probability of local tumor control was 96% (crude rate: 74/77-96.1%), the 4-year probability of overall survival was 96% (crude rate: 74/77-96.1%) in this patient group. In case of the distant metastasis free survival the probability was 89, 5% (crude rate: 70/77-90, 1%). Probability of disease specific survival was 98% (crude rate: 76/77-98. 7%). Local relapse occurred in three cases (3.9%). In ten cases (12.9%) asymptomatic grade I-II breast fibrosis, in eight cases (10.4%) asymptomatic breast fat necrosis were registered. For 14 patients (18.2%) asymptomatic lung fibrosis was recorded on the control CT scans. In term of the relapse free survival, the close resection margin and the nodal positivity resulted in significant difference in favor of the clear resection margin group and the node negative group. In this study the 3-D conformal photon boost resulted in good local control and side effect profile. The presence of tumor bed clips resulted in significantly lower boost PTV volumes, but no correlation was found between the irradiated boost volume and the breast fibrosis. In the relapse free survival analysis, nodal negativity and clear margin status resulted in significantly better RFS.

[Modified mesh implantation technique in traditional femoral hernia repairs]. / A hálóbeültetés technikájának módosítása hagyományos megközelítésu combsérvmutétek esetén.

Mesh implantation techniques are increasingly common in groin hernia repairs in Hungary. The mesh can be inserted via the traditional Lichtenstein technique or laparoscopic methods. We modified the traditional operation technique to reduce the incidence of femoral hernia recurrence. The medial and wider part of the mesh was slid in the preperitoneal space under Cooper's ligament and Lotheissen's sutures were fixed 1.5 centimeters from the edge of the mesh. Thus, in the case of a possible suture insufficiency, the probability of hernia recurrence is reduced due to the adhesion between the mesh and the surrounding tissue.

Effects of intra- and extracellular space properties on diffusion and T(2) relaxation in a tissue model.

The purpose of this study was to investigate the effects of biophysical factors on the diffusion and the relaxation time T(2) independently. Certain properties of the extracellular and the intracellular space may change radically in pathological conditions resulting in water diffusion changes. A tissue model consisting of red blood cells was studied. The extra- and intracellular spaces were modified osmotically and by suspending medium concentration. Diffusion measurements were evaluated with regard to the effective medium theory. Neither the nature of the protein in the extracellular space nor an increased level of intracellular hydration caused a significant net water diffusion change in the cell suspension. The relaxation time T(2) exhibited very little dependence on the extracellular volume fraction or the concentration or the nature of the protein in the extracellular space. An increased level of intracellular hydration resulted in systematically larger T(2) values. It seems probable that increases in extracellular protein concentrations or in the extent of intracellular hydration do not play a significant role in the diffusion changes detected in pathological conditions. T(2) appears to depend on the level of hydration or the total water content but is seemingly less dependent of the concentration and the nature of the extracellular protein in our model solutions.

Technical feasibility of transperineal MR-guided prostate interventions in a low-field open MRI unit: canine study.

Magnetic resonance imaging (MRI) provides superior visualization of the prostate, its substructure, surrounding tissues, and, most important, focal lesions or cancer. The purpose of our canine study was to demonstrate the feasibility of a low-field (0.35 T) transperineal system that enables precise MR image guidance of prostate interventions. The canines were placed in the right lateral decubitus position. Template reconstruction, trajectory planning, contouring were based on T2-weighted FSE images. For image guidance and target confirmation, fast gradient spoiled-echo (FSPGR) sequence was used. MR compatible coaxial needles were manually inserted through the perineum to the base of the prostate. After satisfactory position was confirmed, brachytherapy catheters were placed through the coaxial needles. The mean deviation of the needle displacements was 2.9 mm with a median value of 2.7 mm. 97% of the errors were less than 4.0 mm. The needle placement accuracy was modelled by the Rayleigh distribution with a sigma value of 2.3 mm. Visual confirmation of needle placements was demonstrated on pathology tissue slices. The time needed for each step was: anaesthesia - 15 min, setup and positioning - 15 min, initial imaging - 15 min, template registration, projection - 15 min, contouring, trajectory planning, insertion of 12 needles - 60 min Based on our canine experiences our method seems to be a promising approach for performing feasible, accurate, reliable and high-quality prostate MR guidance within a reasonable time span.

Comparison of photon with electron boost in treatment of early stage breast cancer.

In the treatment of early stage breast cancer breast conserving surgery (BCS) followed by whole breast irradiation (WBI) is a standard method. The impact of the tumor bed boost following WBI is well-defined, but there are various delivery methods. In this study the electron and the photon boost techniques were compared. For 78 early stage breast cancer patients both CT based 3D conformal photon boost and electron boost plans were created. For dosimetric comparison coverage index (CI), external volume index (EI) and conformality index (COIN) were studied. Lung volume receiving a dose of 2 Gy was also reviewed. Seventy-eight patients with 156 plans were compared. The mean tumor bed volume was measured as 61.39 cm3 the mean tumor bed-skin distance was 3.13 cm. In the case of CI and COIN significant differences were found in favor of the photon boost. In the comparison of EI no significant difference was detected between the two techniques. The mean lung volume receiving 2 Gy were 42.3 and 168.35 cm3, for photons and electrons respectively. In the adjuvant treatment of early stage breast cancer WBI followed by conformal photon boost showed to be superior to electron boost in focus of the COIN and CI.

[Tumor movements detected by multi-slice CT-based image fusion in the radiotherapy of lung cancer patients]. / A tumormozgások jelentôségének sokszeletes-CT-alapú képfúziós vizsgálata tüdôdaganatos betegek sugárkezelésénél.

The aim of our study was to detect the possible uncertainties arising from tumor movements in the daily routine treatment planning, in extreme breathing conditions. Ten patients with lung cancer were enrolled into the study. According to tumor location, five patients had peripheral and five had central tumor. After the normal planning CT scan, two more scans were made with the same CT parameters in maximal exhalation and in maximal inhalation. For planning, the normal breathing scans were used with the fusion of the maximal inhalation and maximal exhalation scans. After the fusion in all breathing phases the gross tumor volumes were contoured (GTV1, GTV2, GTV3). Around the GTV1 (normal breathing phase GTV) 3 planning target volumes (PTV) were generated with the margin of 0.5 cm, 1.5 cm and 2.5 cm (PTV1, PTV2, PTV3). Individual plans were generated to all PTVs. All GTV volumes were registered. In all cases volume deviations were registered in different breathing phases (min: 1.5%, max: 35.6%). For GTV coverage comparison the coverage index (CI) was used. In case of extreme breathing conditions, using 0.5 cm margin was sufficient to reach good coverage for central tumors. For peripheral tumors 1.5 cm margin had to be used for the acceptable coverage (CI: 0.85-1.00). In our study, extreme breathing conditions were analyzed. According to our results, CT scans used in the daily routine do not exactly represent the tumor midposition and the true tumor volume. Due to breathing synchronous tumor movements, 0.5 cm margin must be used for planning in central location. In peripheral tumors wider margin should be used.