Monte Carlo Modeling of Dynamic Tumor Tracking on a Gimbaled Linear Accelerator.

Purpose and Aim: The Vero4DRT (Brainlab AG) linear accelerator is capable of dynamic tumor tracking (DTT) by panning/tilting the radiation beam to follow respiratory-induced tumor motion in real time. In this study, the panning/tilting motion is modeled in Monte Carlo (MC) for quality assurance (QA) of four-dimensional (4D) dose distributions created within the treatment planning system (TPS). Materials and Methods: Step-and-shoot intensity-modulated radiation therapy plans were optimized for 10 previously treated liver patients. These plans were recalculated on multiple phases of a 4D computed tomography (4DCT) scan using MC while modeling panning/tilting. The dose distributions on each phase were accumulated to create a respiratory-weighted 4D dose distribution. Differences between the TPS and MC modeled doses were examined. Results: On average, 4D dose calculations in MC showed the maximum dose of an organ at risk (OAR) to be 10% greater than the TPS' three-dimensional dose calculation (collapsed cone [CC] convolution algorithm) predicted. MC's 4D dose calculations showed that 6 out of 24 OARs could exceed their specified dose limits, and calculated their maximum dose to be 4% higher on average (up to 13%) than the TPS' 4D dose calculations. Dose differences between MC and the TPS were greatest in the beam penumbra region. Conclusion: Modeling panning/tilting for DTT has been successfully modeled with MC and is a useful tool to QA respiratory-correlated 4D dose distributions. The dose differences between the TPS and MC calculations highlight the importance of using 4D MC to confirm the safety of OAR doses before DTT treatments.

Monte Carlo based continuous aperture optimization for VMAT on conventional and MR-linacs: A proof of concept.

BACKGROUND: Currently, the commercial treatment planning systems for magnetic-resonance guided linear accelerators (MR-linacs) only support step-and-shoot intensity-modulated radiation therapy (IMRT). However, recent studies have shown the feasibility of delivering arc therapy on MR-linacs, which is expected to improve dose distributions and delivery speed. By accurately accounting for the electron return effect in the presence of a magnetic field, a Monte Carlo (MC) algorithm is ideally suited for the inverse treatment planning of this technique. PURPOSE: We propose a novel MC-based continuous aperture optimization (MCCAO) algorithm for volumetric modulated arc therapy (VMAT), including applications to VMAT on MR-linacs and trajectory-based VMAT. A unique feature of MCCAO is that the continuous character of gantry rotation and multileaf collimator (MLC) motion is accounted for at every stage of the optimization. METHODS: The optimization process uses a multistage simulation of 4D dose distribution. A phase space is scored at the top surface of the MLC and the energy deposition of each particle history is mapped to its position in this phase space. A progressive sampling method is used, where both MLC leaf positions and monitor unit (MU) weights are randomly changed, while respecting the linac mechanical limits. Due to the continuous nature of the leaf motion, such changes affect not only a single control point, but propagate to the adjacent ones as well, and the corresponding dose distribution changes are accounted for. A dose-volume cost function is used, which includes the MC statistical uncertainty. RESULTS: We applied our optimization technique to various treatment sites, using standard and flattening-filter-free (FFF) 6 MV beam models, with and without a 1.5 T magnetic field. MCCAO generates deliverable plans, whose dose distributions are in good agreement with measurements on ArcCHECK and stereotactic radiosurgery End-To-End Phantom. CONCLUSIONS: We show that the novel MCCAO method generates VMAT plans that meet clinical objectives for both conventional and MR-linacs.

Clinical outcomes of modified direct lateral approach of Hardinge for total hip arthroplasty.

The aim of the study was to evaluate a modified direct lateral approach for total hip arthroplasty in terms of clinical and functional outcomes, rate of complications and hospitalization. We retrospectively reviewed the data of 526 patients with THA operated in our department between January 2017 and December 2021. Clinical examination, functional outcome and radiographic evaluation were performed during follow-up. Patients were evaluated at the following time points: preoperatively and postoperatively at 3 days, 6 weeks, 12 weeks and 1 year and we registered surgery related data, complications, Visual Analogue Scale pain score, Harris Hip Score, the Western Ontario McMaster Osteoarthritis Index. Low intraoperative blood loss, short operation time, short hospitalization, early mobilization of the patient and good range of motion imposed the modified direct lateral approach as a valuable procedure for the patients with THA. VAS score evaluated at 3 days and 6 weeks indicated a very good overall postoperative experience. The HHS and Womac scores were evaluated at 6 weeks, 12 weeks and 1 year and showed excellent results. Trendelenburg gait and abductor weakness, traditionally related with direct lateral approach, were not significant statistically and complete reversible. We registered a very low complication rates with good functional outcome. The modified direct lateral approach can lead to superior outcomes, improved quality of life, with reduced intra and postoperative complications rate.

A new DOSXYZnrc method for Monte Carlo simulations of 4D dose distributions.

The purpose of this study is to present a novel method for generating Monte Carlo 4D dose distributions in a single DOSXYZnrc simulation. During a standard simulation, individual energy deposition events are summed up to generate a 3D dose distribution and their associated temporal information is discarded. This means that in order to determine dose distributions as a function of time, separate simulations would have to be run for each interval of interest. Consequently, it has not been clinically feasible until now to routinely perform Monte Carlo simulations of dose rate, time-resolved dose accumulation, or electronic portal imaging devices (EPID) cine-mode images for volumetric modulated arc therapy (VMAT) plans. To overcome this limitation, we modified DOSXYZnrc and defined new input and output variables that allow a time-like parameter associated with each particle history to be binned in a user-defined manner. Under the new code version, computation times are the same as for a standard simulation, and the time-integrated 4D dose is identical to the standard 3D dose. We present a comparison of scintillator measurements and Monte Carlo simulations for dose rate during a VMAT beam delivery, a study of dose rate in a VMAT total body irradiation plan, and simulations of transit (through-patient) EPID cine-mode images.

Experimental investigation of D2 conversion to DHO in soil near the Cernavoda nuclear power plant site in Romania.

The current Canadian and Romanian model predictions for tritium dose following an atmospheric tritiated hydrogen gas (HT) release is based on a default Canadian Standards Association (CSA) conversion factor of HT to tritiated water (HTO) of 4.3%. The determination of an empirical site specific value for the conversion factor was essential for the CANDU Cernavoda Nuclear Power Plant (NPP) in Romania to verify if the CSA value is appropriate for use at this site. Given the role of soil characteristics on the conversion of HT to HTO, on-site experiments would provide the best evaluation of the conversion factor. The objective of the study was to define the soil HT to HTO conversion parameters specific to the Cernavoda NPP site. In June 2016, a series of experiments were conducted to meet this objective. First, the in situ deposition velocity of D2 gas, as a surrogate for HT gas, was obtained using an exposure chamber. Diffusion of D2 into the soil was then evaluated based on the measurements of DHO concentrations in the exposed soil. As soil microbes play a role in the conversion of HT to HTO, this work included a microbiological characterization of the soil, which targeted total soil bacteria (cultivable and gene-based) and hydrogen oxidizing bacteria (cultivable and gene-based). The fraction of hydrogen oxidizing cultivable soil bacteria represented 14-20% of the total cultivable bacteria population estimated as 2.8-29.2 × 105 cfu/g of soil. The empirically derived HT to HTO conversion factor was lower than the default value (4.3%). It fell between 0.9% and 2.0%. The default value is therefore more conservative than the Cernavoda site-specific derived value obtained from the study.

Monte Carlo simulation of 6-MV dynamic wave VMAT deliveries by Vero4DRT linear accelerator using EGSnrc moving sources.

The commissioning and benchmark of a Monte Carlo (MC) model of the 6-MV Brainlab-Mitsubishi Vero4DRT linear accelerator for the purpose of quality assurance of clinical dynamic wave arc (DWA) treatment plans is reported. Open-source MC applications based on EGSnrc particle transport codes are used to simulate the medical linear accelerator head components. Complex radiotherapy irradiations can be simulated in a single MC run using a shared library format combined with BEAMnrc "source20." Electron energy tuning is achieved by comparing measured vs simulated percentage depth doses (PDDs) for MLC-defined field sizes in a water phantom. Electron spot size tuning is achieved by comparing measured and simulated inplane and crossplane beam profiles. DWA treatment plans generated from RayStation (RaySearch) treatment planning system (TPS) are simulated on voxelized (2.5 mm3 ) patient CT datasets. Planning target volume (PTV) and organs at risk (OAR) dose-volume histograms (DVHs) are compared to TPS-calculated doses for clinically deliverable dynamic volumetric modulated arc therapy (VMAT) trajectories. MC simulations with an electron beam energy of 5.9 MeV and spot size FWHM of 1.9 mm had the closest agreement with measurement. DWA beam deliveries simulated on patient CT datasets results in DVH agreement with TPS-calculated doses. PTV coverage agreed within 0.1% and OAR max doses (to 0.035 cc volume) agreed within 1 Gy. This MC model can be used as an independent dose calculation from the TPS and as a quality assurance tool for complex, dynamic radiotherapy treatment deliveries. Full patient CT treatment simulations are performed in a single Monte Carlo run in 23 min. Simulations are run in parallel using the Condor High-Throughput Computing software1 on a cluster of eight servers. Each server has two physical processors (Intel Xeon CPU E5-2650 0 @2.00 GHz), with 8 cores per CPU and two threads per core for 256 calculation nodes.

Hepatocellular carcinoma tumour burden score to stratify prognosis after resection.

BACKGROUND: Although the Barcelona Clinic Liver Cancer (BCLC) staging system has been largely adopted in clinical practice, recent studies have emphasized the need for further refinement and subclassification of this system. METHODS: Patients who underwent hepatectomy with curative intent for BCLC-0, -A or -B hepatocellular carcinoma (HCC) between 2000 and 2017 were identified using a multi-institutional database. The tumour burden score (TBS) was calculated, and overall survival (OS) was examined in relation to TBS and BCLC stage. RESULTS: Among 1053 patients, 63 (6·0 per cent) had BCLC-0, 826 (78·4 per cent) BCLC-A and 164 (15·6 per cent) had BCLC-B HCC. OS worsened incrementally with higher TBS (5-year OS 77·9, 61 and 39 per cent for low, medium and high TBS respectively; P < 0·001). No differences in OS were noted among patients with similar TBS, irrespective of BCLC stage (61·6 versus 58·9 per cent for BCLC-A/medium TBS versus BCLC-B/medium TBS, P = 0·930; 45 versus 13 per cent for BCLC-A/high TBS versus BCLC-B/high TBS, P = 0·175). Patients with BCLC-B HCC and a medium TBS had better OS than those with BCLC-A disease and a high TBS (58·9 versus 45 per cent; P = 0·005). On multivariable analysis, TBS remained associated with OS among patients with BCLC-A (medium TBS: hazard ratio (HR) 2·07, 95 per cent c.i. 1·42 to 3·02, P < 0·001; high TBS: HR 4·05, 2·40 to 6·82, P < 0·001) and BCLC-B (high TBS: HR 3·85, 2·03 to 7·30; P < 0·001) HCC. TBS could also stratify prognosis among patients in an external validation cohort (5-year OS 79, 51·2 and 28 per cent for low, medium and high TBS respectively; P = 0·010). CONCLUSION: The prognosis of patients with HCC varied according to the BCLC stage but was largely dependent on the TBS.

ANTECEDENTES: Aunque el sistema de estadificación del Barcelona Clinic Liver Cancer (BCLC) ha sido adoptado en gran medida en la práctica clínica, estudios recientes han enfatizado la necesidad de un mayor refinamiento y subclasificación del sistema BCLC. MÉTODOS: Los pacientes con carcinoma hepatocelular (hepatocellular cancer, HCC) BCLC-0, A y B que se sometieron a una hepatectomía con intención curativa entre 2000 y 2017 fueron identificados utilizando una base de datos multi-institucional. Se calculó la puntuación de carga tumoral (tumour burden score, TBS) y se examinó la supervivencia global (overall survival, OS) en relación con la TBS y los estadios BCLC. RESULTADOS: En la serie de 1.053 pacientes, 63 (6%) tenían HCC BCLC-0, 826 (78,4%) HCC BCLC-A y 164 (15,6%) HCC BCLC-B. La OS disminuyó de forma incremental en función de la mayor TBS (OS a 5 años; TBS baja: 77,9% versus TBS media: 61% versus TBS alta: 39%, P < 0,001). No se observaron diferencias en la OS entre pacientes con una puntuación TBS similar, independientemente del estadio BCLC (BCLC-A/TBS media: 61,6% versus BCLC-B/TBS media: 58,9%, P = 0,93; BCLC-A/TBS alta: 45,1% versus BCLC-B/TBS alta: 12,8%, P = 0,175). Los pacientes con BCLC-B/TBS media tuvieron una mejor OS que los pacientes con BCLC-A/TBS alta (58,9% versus 45,1%, P = 0,005). En el análisis multivariable, la TBS se mantuvo asociada a la OS en el caso de BCLC-A (TBS media: cociente de riesgos instantáneos, hazard ratio, HR = 2,07, i.c. del 95%: 1,42-3,02, P < 0,001; TBS alta: HR = 4,05, i.c. del 95%: 2,40-6,82, P < 0,001) y BCLC-B pacientes (TBS alta: HR = 3,85, i.c. del 95%: 2,03-7,30, P < 0,001). La TBS también pudo estratificar el pronóstico entre pacientes en una cohorte de validación externa (OS a 5 años; TBS baja: 78,7% versus TBS media: 51,2% versus TBS alta: 27,6%, P = 0,01). CONCLUSIÓN: El pronóstico de los pacientes con HCC varió según el estadio BCLC, pero dependió en gran medida de la TBS.

Amphiphilic polysaccharide based on curdlan: Synthesis and behaviour in aqueous solution.

Amphiphilic polyelectrolyte based on curdlan derivative containing quaternary ammonium groups with a degree of substitution up to 0.4 was synthesized and characterized. The chemical structure of the amphiphilic curdlan derivative was confirmed by FTIR, 13C and 1H NMR spectroscopy. The 2D NMR homo- and heteronuclear correlations were used to attribute the ambiguous 1D NMR signals from 1H and 13C spectra. The hydrodynamic properties of this new derivative were studied by capillary viscometry. The non-linear Wolf equation was used to determine the intrinsic viscosity and the scaling theory was used to delimitate the concentration domains. The self-aggregation of the amphiphilic derivative was studied by fluorescence spectroscopy using pyrene and N-phenylnaphthylamine as micropolarity sensitive probes, and by surface tension measurements. The results obtained from the antibacterial and antifungal tests performed on E. coli, P. aeruginosa bacteria, and C. albicans fungi recommend this new amphiphilic derivative to be used either as a soluble biopolymer or as a precursor for the preparation of new biomaterials with antimicrobial properties.

Azithromycin Fails to Prevent Accelerated Airway Obliteration in T-bet-/- Mouse Lung Allograft Recipients.

BACKGROUND: Cellular and molecular mechanisms of acute and chronic lung allograft rejection have yet to be clearly defined, and obliterative bronchiolitis (OB) remains the primary limitation to survival in lung transplant recipients (LTRs). We have previously shown that T-bet-deficient recipients of full major histocompatibility complex (MHC)-mismatched, orthotopic left lung transplants develop accelerated obliterative airway disease (OAD) in the setting of acute cellular rejection characterized by robust alloimmune CD8+ interleukin (IL)-17 and interferon (IFN)-γ responses that are attenuated with neutralization of IL-17. Azithromycin has been shown to be beneficial in some LTRs with bronchiolitis obliterans syndrome/OB. Here, we evaluated the effects of azithromycin on rejection pathology and T-cell effector responses in T-bet-/- recipients of lung transplants. METHODS: Orthotopic left lung transplantation was performed in BALB/c → B6 wild type or BALB/c → B6 T-bet-/- strain combinations as previously described. Mice treated with azithromycin received 10 mg/kg or 50 mg/kg subcutaneously daily. Lung allograft histopathology was analyzed at day 10 or day 21 post-transplantation, and neutrophil staining for quantification was performed using anti-myeloperoxidase. Allograft mononuclear cells were isolated at day 10 for T-cell effector cytokine response assessment using flow cytometry. RESULTS: We show that while azithromycin significantly decreases lung allograft neutrophilia and CXCL1 levels and attenuates allospecific CD8+ IL-17 responses early post-transplantation, OAD persists in T-bet-deficient mice. CONCLUSIONS: Our results indicate that lung allograft neutrophilia is not essential for the development of OAD in this model and suggest allospecific T-cell responses that remain despite marked attenuation of CD8+ IL-17 are sufficient for obliterative airway inflammation and fibrosis.

Trends in use of lymphadenectomy in surgery with curative intent for intrahepatic cholangiocarcinoma.

BACKGROUND: The role of routine lymph node dissection (LND) in the surgical treatment of intrahepatic cholangiocarcinoma (ICC) remains controversial. The objective of this study was to investigate the trends of LND use in the surgical treatment of ICC. METHODS: Patients undergoing curative intent resection for ICC in 2000-2015 were identified from an international multi-institutional database. Use of lymphadenectomy was evaluated over time and by geographical region (West versus East); LND use and final nodal status were analysed relative to AJCC T categories. RESULTS: Among the 1084 patients identified, half (535, 49·4 per cent) underwent concomitant hepatic resection and LND. Between 2000 and 2015, the proportion of patients undergoing LND for ICC nearly doubled: 44·4 per cent in 2000 versus 81·5 per cent in 2015 (P < 0·001). Use of LND increased over time among both Eastern and Western centres. The odds of LND was associated with the time period of surgery and the extent of the tumour/T status (referent T1a: OR 2·43 for T2, P = 0·001; OR 2·13 for T3, P = 0·016). Among the 535 patients who had LND, lymph node metastasis (LNM) was noted in 209 (39·1 per cent). Specifically, the incidence of LNM was 24 per cent in T1a disease, 22 per cent in T1b, 42·9 per cent in T2, 48 per cent in T3 and 66 per cent in T4 (P < 0·001). AJCC T3 and T4 categories, harvesting of six or more lymph nodes, and presence of satellite lesions were independently associated with LNM. CONCLUSION: The rate of LNM was high across all T categories, with one in five patients with T1 disease having nodal metastasis. The trend in increased use of LND suggests a growing adoption of AJCC recommendations in the treatment of ICC.

THE ROLE OF SURGERY IN A PATIENT WITH CARCINOID SYNDROME, COMPLICATED BY CARCINOID HEART DISEASE.

A 55-year-old female patient was admitted for flushing and abdominal pain in the right upper quadrant. Her past medical history revealed high blood pressure and a recent echocardiography showed thickened appearance of tricuspid valve with coaptation defect and grade II tricuspid regurgitation. Contrast enhanced abdominal CT scan and MRI were subsequently performed and revealed a large macronodular liver mass, as well as other micronodular lesions disseminated in the liver parenchyma. CT guided biopsy from the main liver mass revealed neuroendocrine tumor of unknown origin (probably GI) with Ki-67 of 8%. Surgical exploration was decided. During laparotomy, the primary tumor was found in the proximal ileum and the patient underwent segmental enterectomy. Non-anatomical hepatectomy was also performed to remove the bulk of the tumor burden (more than 90%). Postoperative course was uneventful and the carcinoid syndrome relieved. At present, 15 months postoperatively, the patient is under treatment with somatostatin analogue for its antiproliferative effect, with good clinical, biochemical and tumoral control and stable heart disease. In patients with neuroendocrine liver metastases from unknown primary, surgical exploration could allow detection (and resection) of the primary tumor and surgical debulking of liver metastases to control carcinoid syndrome and carcinoid heart disease.

PROGNOSTIC FACTORS IN PATIENTS WITH SURGICAL RESECTION OF PANCREATIC NEUROENDOCRINE TUMOURS.

CONTEXT: Pancreatic neuroendocrine tumours (PanNETs) are rare pancreatic neoplasms. PanNETs can be treated by multimodal approach including surgery, locoregional and systemic therapy. OBJECTIVE: The aim of the present study is to evaluate predictive factors of overall survival in patients with PanNETs surgically treated at a single center. SUBJECTS AND METHODS: The study group consisted of 120 patients with PanNETs who had undergone surgery at the Center of Digestive Diseases and Liver Transplantation of Fundeni Clinical Institute, Bucharest, Romania. Surgical resection of the primary tumor was performed in 110 patients. RESULTS: Tumor size > 2 cm (p=0.048) (90% CI) lymph node involvement (p=0.048), ENET grade (p<0.001), distant metastases (p<0.001), Ki 67 index (<2%, 2-5%, 5-10%, 10-20%, >20%) (p<0.001) were identified as significant prognostic factors for OS on univariate analysis. Using multivariate Cox proportional regression model we found that distant metastases and Ki 67 index were independent risk factors for the survival outcome. CONCLUSIONS: Surgery with curative intent should be considered in all cases if clinically appropriate and technically feasible. High grade (Ki67 index ≥10%) tumours were associated with a 2- fold increase in risk of death as compared to those with a Ki67 <10%.

Early versus late recurrence of intrahepatic cholangiocarcinoma after resection with curative intent.

BACKGROUND: The objective of this study was to investigate the characteristics, treatment and prognosis of early versus late recurrence of intrahepatic cholangiocarcinoma (ICC) after hepatic resection. METHODS: Patients who underwent resection with curative intent for ICC were identified from a multi-institutional database. Data on clinicopathological characteristics, initial operative details, timing and sites of recurrence, recurrence management and long-term outcomes were analysed. RESULTS: A total of 933 patients were included. With a median follow-up of 22 months, 685 patients (73·4 per cent) experienced recurrence of ICC; 406 of these (59·3 per cent) developed only intrahepatic disease recurrence. The optimal cutoff value to differentiate early (540 patients, 78·8 per cent) versus late (145, 21·2 per cent) recurrence was defined as 24 months. Patients with early recurrence had extrahepatic disease more often (44·1 per cent versus 28·3 per cent in those with late recurrence; P < 0·001), whereas late recurrence was more often only intrahepatic (71·7 per cent versus 55·9 per cent for early recurrence; P < 0·001). From time of recurrence, overall survival was worse among patients who had early versus late recurrence (median 10 versus 18 months respectively; P = 0·029). In multivariable analysis, tumour characteristics including tumour size, number of lesions and satellite lesions were associated with an increased risk of early intrahepatic recurrence. In contrast, only the presence of liver cirrhosis was independently associated with an increased likelihood of late intrahepatic recurrence (hazard ratio 1·99, 95 per cent c.i. 1·11 to 3·56; P = 0·019). CONCLUSION: Early and late recurrence after curative resection for ICC are associated with different risk factors and prognosis. Data on the timing of recurrence may inform decisions about the degree of postoperative surveillance, as well as help counsel patients with regard to their risk of recurrence.

Long-term outcomes of patients with 10 or more colorectal liver metastases.

BACKGROUND: Although the number of colorectal liver metastases (CLM) is decreasingly considered as a contraindication to surgery, patients with 10 CLM or more are often denied liver surgery. This study aimed to evaluate the outcome after liver surgery and to identify prognostic factors of survival in such patients. METHODS: The study population consisted of a multicentre cohort of patients with CLM (N=12 406) operated on, with intention to resect, from January 2005-June 2013 and whose data were prospectively collected in the LiverMetSurvey registry. RESULTS: Overall, the group ⩾10 CLM (N=529, 4.3%) experienced a 5-year overall survival (OS) of 30%. A macroscopically complete (R0/R1) resection (72.8% of patients) was associated with a 3- and 5-year OS of 61% and 39% vs 29% and 5% for R2/no resection patients (P<0.0001). At multivariate analysis, R0/R1 resection emerged as the strongest favourable factor of OS (HR 0.35 (0.26-0.48)). Other independent favourable factors were as follows: maximal tumour size <40 mm (HR 0.67 (0.49-0.92)); age <60 years (HR 0.66 (0.50-0.88)); preoperative MRI (HR 0.65 (0.47-0.89)); and adjuvant chemotherapy (HR 0.73 (0.55-0.98)). The model showed that 5-year OS rates of 30% was possible provided R0/R1 resection associated with at least an additional favourable factor. CONCLUSIONS: Liver resection might provide long-term survival in patients with ⩾10 CLM staged with preoperative MRI, provided R0/R1 resection followed by adjuvant therapy. A validation of these results in another cohort is needed.

RENEB - THE ROMANIAN PERSPECTIVE.

The European Commission supports the development of an European network in biodosimetry (RENEB), in which a large number of experienced laboratories from 16 European countries are involved. The final goal will be the significant improvement of the biodosimetry capacity for response to accidents and radiological emergencies, based on a well-organized cooperative action with a rapid and rigorous dose assessment. The project is aimed at consolidating the network with its operational platform, inter-comparison exercises, training activities, proceedings in quality assurance and implementation and integration of new network partners and new methods. In the project context, the Romanian perspective on the participation benefits for the Romanian biodosimetry is described.

["Barking" micturition noise as sign of acute hip-TEP-late infection]. / "Bellendes" Miktionsgeräusch als Ursachenzeichen des akuten Hüft-TEP-Spätinfektes.

This article presents the case of a patient with an acute late infection of the hip prosthesis. At first, complaints in the hip region were in the foreground. Shortly after the revision operation the patient noticed a barking noise during micturition, as sign of a pneumaturia. The following diagnostics showed a perforated sigmoid diverticulitis with a sigmoid-urinary bladder-fistula.

Dose rate mapping of VMAT treatments.

Human tissues exhibit a varying response to radiation dose depending on the dose rate and fractionation scheme used. Dose rate effects have been reported for different radiations, and tissue types. The literature indicates that there is not a significant difference in response for low-LET radiation when using dose rates between 1 Gy min(-1) and 12 Gy min(-1) but lower dose rates have an observable sparing effect on tissues and a differential effect between tissues. In intensity-modulated radiotherapy such as volumetric modulated arc therapy (VMAT) the dose can be delivered with a wide range of dose rates. In this work we developed a method based on time-resolved Monte Carlo simulations to quantify the dose rate frequency distribution for clinical VMAT treatments for three cancer sites, head and neck, lung, and pelvis within both planning target volumes (PTV) and normal tissues. The results show a wide range of dose rates are used to deliver dose in VMAT and up to 75% of the PTV can have its dose delivered with dose rates <1 Gy min(-1). Pelvic plans on average have a lower mean dose rate within the PTV than lung or head and neck plans but a comparable mean dose rate within the organs at risk. Two VMAT plans that fulfil the same dose objectives and constraints may be delivered with different dose rate distributions, particularly when comparing single arcs to multiple arc plans. It is concluded that for dynamic plans, the dose rate range used varies to a larger degree than previously assumed. The effect of the dose rate range in VMAT on clinical outcome is unknown.

Techniques for adaptive prostate radiotherapy.

Variations in the position and shape of the prostate make accurate setup and treatment challenging. Adaptive radiation therapy (ART) techniques seek to alter the treatment plan, at one or more points throughout the treatment course, in response to changes in patient anatomy observed between planning and pre-treatment images. This article reviews existing and developing ART techniques for prostate cancer along with an overview of supporting in-room imaging technologies. Challenges to the clinical implementation of adaptive radiotherapy are also discussed.

A method to perform multi-scale Monte Carlo simulations in the clinical setting.

In order to model the track structure of clinical mega-voltage photon beams in a reasonable time, it is necessary to use a multi-scale approach incorporating a track-structure algorithm for the regions of interest and a condensed history algorithm for the rest of the geometry. This paper introduces a multi-scale Monte Carlo system, which is used to hand off particle trajectory information between the two algorithms. Since condensed history algorithms ignore electrons with energy below a fixed threshold and those electrons are important to the track structure on the micrometre scale, it is necessary to hand over all charged particles to the track-structure algorithm only in a volume that extends beyond the scoring volume. Additionally, the system is validated against experimental results for radio-isotope gamma spectra.

Robotically performed total mesorectal excision for rectal cancer.

BACKGROUND: Rectal cancer is an important health problem, due to the increasing number of new cases and the quality of life issues brought forth by surgical treatment in these patients. AIM: The aim of the study was to analyse the results of robotic surgery in the treatment of lower and middle rectal cancer,locations in which TME is performed. MATERIAL AND METHOD: Patients diagnosed with and operated on for rectal cancer by the means of robotic surgery between 2008-2012 at the Fundeni Clinical Institute were retrospectively analysed. RESULTS: A number of 117 patients with rectal cancer were operated on by robotic surgery, of which 79 (67.52%) were submitted to total mesorectal excision (TME). The most frequently performed surgery was low anterior resection, followed by rectal amputation through abdominoperineal approach.Anastomosis fistula was observed in 9 (11.39%) patients. Local recurrence was encountered in 2 (2.53%) of the robotically performed surgeries. CONCLUSIONS: 1. Robotically assisted total mesorectal excision is feasible, safe and can be performed with a small number of complications and a low local recurrence rate; 2. The main advantages are oncological safety and quality of life; 3.Conversion to open surgery is rarely encountered; 4. Protection loop ileostomy existence allows avoiding reintervention in case anastomotic fistula occurs in patients with low anterior resection. 5. Robotic surgery may become gold standard in the surgical treatment of rectal cancer.