Comparison of two optimization algorithms (VOLOTM , SEQU) for CyberKnife® treatment of acoustic neuromas, lung metastases, and liver metastases

INTRODUCTION

Two optimization algorithms VOLO™ and sequential optimization algorithm (SEQU) are compared in the Precision® treatment planning system from Accuray® for stereotactic radiosurgery and stereotactic body radiotherapy (SBRT) treatment plans. The aim is to compare the two algorithms to assess if VOLO™ is better of SEQU in certain treatment site.

MATERIALS AND METHODS

Sixty clinical treatment cases were compared. Entities include Acoustic neuroma (AN), lung metastases, and liver metastases. In each entity, 10 SEQU and 10 VOLO™ treatment plans were optimized. The Ray-Tracing calculation algorithm was used for all treatment plans and the treatments were planned exclusively with fixed cones (5-50 mm). The number of nodes, beams, total MU, and treatment time were compared. Conformity index (CI), new conformity index (nCI), homogeneity index (HI), gradient index (GI), and target coverage were examined for agreement. Dmin , Dmean , Dmax , D100%, D98%, and D2% dose in the target volume as well as exposure to organs at risk was checked. To determine peripheral doses, the isodose volumes from V10% to V98% were evaluated.

RESULTS

AN treatment plans showed significant differences for the number of nodes, beams, total MU, treatment time, D98%, D100% for the target volume, and the doses for all organs at risk. VOLO™ achieved better results on average. Total MU, treatment time, coverage, and D98% are significantly better for VOLO™ for lung metastases. For liver metastases, a significant reduction in number of nodes, total MU, and treatment time was observed for VOLO™ plans. The mean target coverage increased slightly with VOLO™, while the mean CI deteriorated slightly. The averages of Dmin , Dmean , D98%, D100%, and V80% resulted in a significant increase for VOLO™.

CONCLUSION

The results of the present study indicate that VOLO™ should be used in place of SEQU as a standard for AN cases moving forward. Despite the lack of significance in the lung and liver cases, VOLO™ optimization is recommended because OAR sparing was similar, but coverage, Dmin , and Dmean were increased, and thus better tumor control can be expected.

Development of a LINAC head model for the CyberKnife VSI-System using EGSnrc Monte Carlo system

INTRODUCTION

In order to understand the interaction processes of photons and electrons of the CyberKnife VSI-System, a modeling of the LINAC head must take place. Here, a Monte Carlo simulation can help. By comparing the measured data with the simulation data, the agreement can be checked.

MATERIALS AND METHODS

For the Monte Carlo simulations, the toolkit EGSnrc with the user codes BEAMnrc and DOSXZYnrc was used. The CyberKnife VSI-System has two collimation systems to define the field size of the beam. On the one hand, it has 12 circular collimators and, on the other, an IRIS-aperture. The average energy, final source width, dose profiles, and output factors in a voxel-based water phantom were determined and compared to the measured data.

RESULTS

The average kinetic energy of the electron beam for the CyberKnife VSI LINAC head is 6.9 MeV, with a final source width of 0.25 cm in x-direction and 0.23 cm in y-direction. All simulated dose profiles for both collimation systems were able to achieve a global gamma criterion of 1%/1 mm to the measured data. For the output factors, the deviation from simulated to measured data is < 1% from a field size of 12.5 mm for the circular collimators and from a field size of 10 mm for the IRIS-aperture.

CONCLUSION

The beam characteristics of the CyberKnife VSI LINAC head could be exactly simulated with Monte Carlo simulation. Thus, in the future, this model can be used as a basis for electronic patient-specific QA or to determine scattering processes of the LINAC head.

Introduction: Improved aquatic animal health management is vital to aquaculture's role in global food security

Global food security and nutrition depend heavily on aquaculture, the continued growth of which is crucial as the world heads towards a human population of at least 9 billion by 2050, while harvests from wild capture will, at best, stabilise at current levels. Thus, a fundamental question is: how can we sustainably increase aquatic food production? It is clear that aquatic animal diseases present a substantial threat and, consequently, aquatic animal health management has a critical role in food security. An ecosystem approach to aquaculture will mitigate impacts on ecosystem services and biodiversity, and provide the necessary resilience to future disease threats, including those exacerbated by climate change. Due to the nature of aquatic production systems, this approach must encompass fisheries and other sectors that share the same resources. Improved aquatic animal health management must be a key component of aquaculture's future. At the national level, public-private partnerships are vital in achieving objectives of common benefit. Improved disease reporting and response is critical in the control of listed and emerging diseases and can only be achieved through government, industry and stakeholder collaboration. Great potential exists to improve biosecurity from the farm to national level, but this will only be achieved through collaboration. Industry cannot develop effective biosecurity without a clear government strategy and support, specifically legislation which provides an effective framework for safe trade. Governments have a key role in creating a regulatory environment that supports effective biosecurity and is attractive to investment; such as one that supports the development and regulatory approval of therapeutics. The improved control of transboundary diseases requires the wider and more consistent implementation of OIE standards, particularly on disease notification. This can only be achieved through improved collaboration between trading partners and by supporting low- and middle-income countries to strengthen their aquatic animal health services. There is incredible potential for aquaculture to continue its rapid growth and increase its contribution to global food security. However, sustainable growth of aquaculture is threatened by both known diseases, which we cannot effectively control, and new diseases, which may become pandemic. Recent pandemics have shown that global production systems are epidemiologically connected and, consequently, aquatic animal diseases present a shared global threat that demands global solidarity. The world now depends on a sustainable future for aquaculture and improved aquatic animal health management is critical to its continued and growing contribution to global food security.

A new approach to the management of emerging diseases of aquatic animals

Since 1970, aquaculture has grown at a rate of between 5% and 10% per annum. It has achieved this by expanding into new areas, farming new (often non-native) species and intensifying production. These features of aquaculture, combined with large-scale movements of animals, have driven disease emergence, with negative consequences for both production and biodiversity. Efforts to improve the management of emerging diseases of aquatic animals must include actions to reduce the rate of disease emergence, enhance disease detection and reporting, and improve responses to prevent disease spread. The rate of disease emergence can be reduced by understanding the underpinning mechanisms and developing measures to mitigate them. The three principal mechanisms of disease emergence, namely, host switching, decreased host immunocompetence and increased pathogen virulence, have many drivers. The most important of these drivers are those that expose susceptible hosts to novel pathogens (e.g. the introduction of non-native hosts, translocation of pathogens, and increased interaction between wild and farmed populations), followed by host switching. Exposure to wild populations can be reduced through infrastructure and management measures to reduce escapes or exclude wild animals (e.g. barrier nets, filtration and closed-confinement technology). A high standard of health management ensures immunocompetence and resistance to putative new pathogens and strains, and thus reduces the rate of emergence. Appropriate site selection and husbandry can reduce the likelihood of pathogens developing increased virulence by preventing their continuous cycling in geographically or temporally linked populations. The under-reporting of emerging aquatic animal diseases constrains appropriate investigation and timely response. At the producer level, employing information and communications technology (e.g. smartphone applications and Cloud computing) to collect and manage data, coupled with a farmer-centric approach to surveillance, could improve reporting. In addition, reporting behaviours must be understood and disincentives mitigated. At the international level, improving the reporting of emerging diseases to the World Organisation for Animal Health allows Member Countries to implement appropriate measures to reduce transboundary spread. Reporting would be incentivised if the global response included the provision of support to low-income countries to, in the short term, control a reported emerging disease, and, in the longer term, develop aquatic animal health services. Early detection and reporting of emerging diseases are only of benefit if Competent Authorities' responses prevent disease spread. Effective responses to emerging diseases are challenging because basic information and tools are often lacking. Consequently, responses are likely to be sub-optimal unless contingency plans have been developed and tested, and decision-making arrangements have been well established.

Sharing responsibility between public and private sectors for the management of aquatic emergency animal diseases

Aquatic animal disease outbreaks affect both the public (represented by the government) and the private sector (represented by the aquaculture and fisheries industry). However, all too often, the responsibilities and costs of responding to an outbreak may not be shared. Without a mechanism for public and private sectors to work together, the outcomes of an emergency response may not be ideal, or of common benefit to all potentially affected parties. In Australia, a mechanism is being developed for public and private sectors to share the responsibilities and costs of responding to aquatic animal disease outbreaks, through an industry- government aquatic emergency animal disease response agreement. The agreement provides an approach for both public and private sectors to share the responsibilities and costs of responding to a disease outbreak and to coordinate disease prevention activities to reduce their shared risk. The key elements of the agreement include provisions to incentivise faster notification of disease outbreaks, facilitate a faster response, share decision-making and costs (including compensation for affected businesses), clarify the responsibilities of all parties and, most importantly, strengthen risk mitigation activities. This paper describes how the draft agreement has been developed among 18 industry and government parties, how key elements of the agreement may contribute to improved aquatic animal health outcomes, and the principles which could be applied by other OIE Member Countries.

The impact of local control on overall survival after stereotactic body radiotherapy for liver and lung metastases from colorectal cancer: a combined analysis of 388 patients with 500 metastases

BACKGROUND

The aim of this analysis was to model the effect of local control (LC) on overall survival (OS) in patients treated with stereotactic body radiotherapy (SBRT) for liver or lung metastases from colorectal cancer.

METHODS

The analysis is based on pooled data from two retrospective SBRT databases for pulmonary and hepatic metastases from 27 centers from Germany and Switzerland. Only patients with metastases from colorectal cancer were considered to avoid histology as a confounding factor. An illness-death model was employed to model the relationship between LC and OS.

RESULTS

Three hundred eighty-eight patients with 500 metastatic lesions (lung n = 209, liver n = 291) were included and analyzed. Median follow-up time for local recurrence assessment was 12.1 months. Ninety-nine patients with 112 lesions experienced local failure. Seventy-one of these patients died after local failure. Median survival time was 27.9 months in all patients and 25.4 months versus 30.6 months in patients with and without local failure after SBRT. The baseline risk of death after local failure exceeds the baseline risk of death without local failure at 10 months indicating better survival with LC.

CONCLUSION

In CRC patients with lung or liver metastases, our findings suggest improved long-term OS by achieving metastatic disease control using SBRT in patients with a projected OS estimate of > 12 months.

Data-driven gating in PET: Influence of respiratory signal noise on motion resolution

PURPOSE

Data-driven gating (DDG) approaches for positron emission tomography (PET) are interesting alternatives to conventional hardware-based gating methods. In DDG, the measured PET data themselves are utilized to calculate a respiratory signal, that is, subsequently used for gating purposes. The success of gating is then highly dependent on the statistical quality of the PET data. In this study, we investigate how this quality determines signal noise and thus motion resolution in clinical PET scans using a center-of-mass-based (COM) DDG approach, specifically with regard to motion management of target structures in future radiotherapy planning applications.

METHODS

PET list mode datasets acquired in one bed position of 19 different radiotherapy patients undergoing pretreatment [¹⁸ F]FDG PET/CT or [¹⁸ F]FDG PET/MRI were included into this retrospective study. All scans were performed over a region with organs (myocardium, kidneys) or tumor lesions of high tracer uptake and under free breathing. Aside from the original list mode data, datasets with progressively decreasing PET statistics were generated. From these, COM DDG signals were derived for subsequent amplitude-based gating of the original list mode file. The apparent respiratory shift d from end-expiration to end-inspiration was determined from the gated images and expressed as a function of signal-to-noise ratio SNR of the determined gating signals. This relation was tested against additional 25 [¹⁸ F]FDG PET/MRI list mode datasets where high-precision MR navigator-like respiratory signals were available as reference signal for respiratory gating of PET data, and data from a dedicated thorax phantom scan.

RESULTS

All original 19 high-quality list mode datasets demonstrated the same behavior in terms of motion resolution when reducing the amount of list mode events for DDG signal generation. Ratios and directions of respiratory shifts between end-respiratory gates and the respective nongated image were constant over all statistic levels. Motion resolution d/d_max could be modeled as d/dmax=1-e-1.52(SNR-1)0.52, with d_max as the actual respiratory shift. Determining d_max from d and SNR in the 25 test datasets and the phantom scan demonstrated no significant differences to the MR navigator-derived shift values and the predefined shift, respectively.

CONCLUSIONS

The SNR can serve as a general metric to assess the success of COM-based DDG, even in different scanners and patients. The derived formula for motion resolution can be used to estimate the actual motion extent reasonably well in cases of limited PET raw data statistics. This may be of interest for individualized radiotherapy treatment planning procedures of target structures subjected to respiratory motion.

Comparison of treatment plans calculated by Ray Tracing and Monte Carlo algorithms for head and thorax radiotherapy with Cyberknife

This study investigates differences between treatment plans generated by Ray Tracing (RT) and Monte Carlo (MC) calculation algorithms in homogeneous and heterogeneous body regions. Particularly, we focus on the head and on the thorax, respectively, for robotic stereotactic radiotherapy and radiosurgery with Cyberknife. Radiation plans for tumors located in the head and in the thorax region have been calculated and compared to each other in 47 cases and several tumor types.

Assuming MC as the algorithm of highest accuracy it is shown that based on selected dose parameters, RT slightly underestimates the dose in homogeneous regions and overestimates in heterogeneous regions. In addition, deviations occur due to tumor size rendering large differences for small tumors. We conclude that dose prescriptions for radiotherapy treatments should differentiate between RT and MC calculation algorithm. This is especially important for small tumors in heterogeneous body regions.

Planning benchmark study for SBRT of early stage NSCLC : Results of the DEGRO Working Group Stereotactic Radiotherapy

PURPOSE

The aim was to evaluate stereotactic body radiation therapy (SBRT) treatment planning variability for early stage nonsmall cell lung cancer (NSCLC) with respect to the published guidelines of the Stereotactic Radiotherapy Working Group of the German Society for Radiation Oncology (DEGRO).

MATERIALS AND METHODS

Planning computed tomography (CT) scan and the structure sets (planning target volume, PTV; organs at risk, OARs) of 3 patients with early stage NSCLC were sent to 22 radiotherapy departments with SBRT experience: each department was asked to prepare a treatment plan according to the DEGRO guidelines. The prescription dose was 3 fractions of 15 Gy to the 65% isodose.

RESULTS

In all, 87 plans were generated: 36 used intensity-modulated arc therapy (IMAT), 21 used three-dimensional conformal radiation therapy (3DCRT), 6 used static field intensity-modulated radiation therapy (SF-IMRT), 9 used helical radiotherapy and 15 used robotic radiosurgery. PTV dose coverage and simultaneously kept OARs doses were within the clinical limits published in the DEGRO guidelines. However, mean PTV dose (mean 58.0 Gy, range 52.8-66.4 Gy) and dose conformity indices (mean 0.75, range 0.60-1.00) varied between institutions and techniques (p ≤ 0.02). OARs doses varied substantially between institutions, but appeared to be technique independent (p = 0.21).

CONCLUSION

All studied treatment techniques are well suited for SBRT of early stage NSCLC according to the DEGRO guidelines. Homogenization of SBRT practice in Germany is possible through the guidelines; however, detailed treatment plan characteristics varied between techniques and institutions and further homogenization is warranted in future studies and recommendations. Optimized treatment planning should always follow the ALARA (as low as reasonably achievable) principle.

Nomogram based overall survival prediction in stereotactic body radiotherapy for oligo-metastatic lung disease

BACKGROUND

Radical local treatment of pulmonary metastases is practiced with increasing frequency due to acknowledgment and better understanding of oligo-metastatic disease. This study aimed to develop a nomogram predicting overall survival (OS) after stereotactic body radiotherapy (SBRT) for pulmonary metastases.

PATIENTS AND METHODS

A multi-institutional database of 670 patients treated with SBRT for pulmonary metastases was used as training cohort. Cox regression analysis with bidirectional variable elimination was performed to identify factors to be included into the nomogram model to predict 2-year OS. The calibration rate of the nomogram was assessed by plotting the actual Kaplan-Meier 2-year OS against the nomogram predicted survival. The nomogram was externally validated using two separate monocentric databases of 145 and 92 patients treated with SBRT for pulmonary metastases.

RESULTS

The median follow up of the trainings cohort was 14.3months, the 2-year and 5-year OS was 52.6% and 23.7%, respectively. Karnofsky performance index, type of the primary tumor, control of the primary tumor, maximum diameter of the largest treated metastasis and number of metastases (1 versus >1) were significant prognostic factors in the Cox model (all p<0.05). The calculated concordance-index for the nomogram was 0.73 (concordance indexes of all prognostic factors between 0.54 and 0.6). Based on the nomogram the training cohort was divided into 4 groups and 2-year OS ranged between 24.2% and 76.1% (predicted OS between 30.2% and 78.4%). The nomogram discriminated between risk groups in the two validation cohorts (concordance index 0.68 and 0.67).

CONCLUSIONS

A nomogram for prediction of OS after SBRT for pulmonary metastases was generated and externally validated. This tool might be helpful for interdisciplinary discussion and evaluation of local and systemic treatment options in the oligo-metastatic setting.

KEY MESSAGE

A nomogram for prediction of overall survival after stereotactic body radiotherapy (SBRT) for pulmonary metastases was developed and externally validated. This tool might be helpful for interdisciplinary discussion and evaluation of local and systemic treatment options in the oligo-metastatic setting.

Influence of Institutional Experience and Technological Advances on Outcome of Stereotactic Body Radiation Therapy for Oligometastatic Lung Disease

PURPOSE

Many technological and methodical advances have made stereotactic body radiotherapy (SBRT) more accurate and more efficient during the last years. This study aims to investigate whether experience in SBRT and technological innovations also translated into improved local control (LC) and overall survival (OS).

METHODS AND MATERIALS

A database of 700 patients treated with SBRT for lung metastases in 20 German centers between 1997 and 2014 was used for analysis. It was the aim of this study to investigate the impact of fluorodeoxyglucose positron-emission tomography (FDG-PET) staging, biopsy confirmation, image guidance, immobilization, and dose calculation algorithm, as well as the influence of SBRT experience, on LC and OS.

RESULTS

Median follow-up time was 14.3 months (range, 0-131.9 months), with 2-year LC and OS of 81.2% (95% confidence interval [CI] 75.8%-85.7%) and 54.4% (95% CI 50.2%-59.0%), respectively. In multivariate analysis, all treatment technologies except FDG-PET staging did not significantly influence outcome. Patients who received pre-SBRT FDG-PET staging showed superior 1- and 2-year OS of 82.7% (95% CI 77.4%-88.6%) and 64.8% (95% CI 57.5%-73.3%), compared with patients without FDG-PET staging resulting in 1- and 2-year OS rates of 72.8% (95% CI 67.4%-78.8%) and 52.6% (95% CI 46.0%-60.4%), respectively (P=.012). Experience with SBRT was identified as the main prognostic factor for LC: institutions with higher SBRT experience (patients treated with SBRT within the last 2 years of the inclusion period) showed superior LC compared with less-experienced centers (P≤.001). Experience with SBRT within the last 2 years was independent from known prognostic factors for LC.

CONCLUSION

Investigated technological and methodical advancements other than FDG-PET staging before SBRT did not significantly improve outcome in SBRT for pulmonary metastases. In contrast, LC was superior with increasing SBRT experience of the individual center.

Local tumor control probability modeling of primary and secondary lung tumors in stereotactic body radiotherapy

BACKGROUND AND PURPOSE

To evaluate whether local tumor control probability (TCP) in stereotactic body radiotherapy (SBRT) varies between lung metastases of different primary cancer sites and between primary non-small cell lung cancer (NSCLC) and secondary lung tumors.

MATERIALS AND METHODS

A retrospective multi-institutional (n=22) database of 399 patients with stage I NSCLC and 397 patients with 525 lung metastases was analyzed. Irradiation doses were converted to biologically effective doses (BED). Logistic regression was used for local tumor control probability (TCP) modeling and the second-order bias corrected Akaike Information Criterion was used for model comparison.

RESULTS

After median follow-up of 19 months and 16 months (n.s.), local tumor control was observed in 87.7% and 86.7% of the primary and secondary lung tumors (n.s.), respectively. A strong dose-response relationship was observed in the primary NSCLC and metastatic cohort but dose-response relationships were not significantly different: the TCD90 (dose to achieve 90% TCP; BED of maximum planning target volume dose) estimates were 176 Gy (151-223) and 160 Gy (123-237) (n.s.), respectively. The dose-response relationship was not influenced by the primary cancer site within the metastatic cohort.

CONCLUSIONS

Dose-response relationships for local tumor control in SBRT were not different between lung metastases of various primary cancer sites and between primary NSCLC and lung metastases.

Using the Neptune project to benefit Australian aquatic animal health research

Diseases of aquatic animals have had, and continue to have, a significant impact on aquatic animal health. In Australia, where fisheries and aquaculture are important industries, aquatic species have been subject to serious disease outbreaks, including pilchard herpesvirus, the cause of one of the largest wild fish kills ever recorded. At the same time, there is a consensus that Australia's parasite fauna are largely unknown, and that aquatic animal health information is difficult to access. Managing aquatic animal diseases is challenging because they may be entirely new, their hosts may be new to aquaculture, and specialist expertise and basic diagnostic tools may be lacking or absent. The Neptune project was created in response to these challenges, and it aims to increase awareness of aquatic animal diseases, improve disease management, and promote communication between aquatic animal health professionals in Australia. The project consists of an online database, a digital microscopy platform containing a whole-slide image library, a community space, and online communications technology. The database contains aquatic animal health information from published papers, government reports, and other sources, while the library contains slides of key diseases both endemic and exotic to Australia. These assets make Neptune a powerful resource for researchers, students, and biosecurity officials.

A case of radiotherapy for an advanced bronchial carcinoma patient with implanted cardiac rhythm machines as well as heart assist device

We present a case of radiotherapy for a 66-year-old patient with squamous cell carcinoma on the left main bronchus undergoing implantation of pacemaker, implantable cardioverter defibrillator (ICD) as well as cardiopulmonary support (CPS) device. The radiation area was determined according to 4D List Mode positron emission tomography–computed tomography (PET-CT) data. Planning Target Volume (PTV) included a part of the active ICD. For the optimal tumor coverage and sparing of both the implantable cardiac devices and organs at risk, we combined the conformal radiotherapy with stereotactic body radiotherapy (SBRT) using helical tomotherapy. The prescription dose of 25.2Gy was applied by conventional radiotherapy. SBRT was performed hypofractionated with a prescription dose of 35Gy in 5 fractions. A dynamic electrocardiogram was performed during every radiation fraction. The implanted aggregates were checked three times a week. Despite partial localization of the active ICD in the radiation field, the tumor was treated without inappropriate shock delivery during radiation treatment and over twelve months afterwards. The reduced tumor size as well as tumor metabolic activity were observed by PET-CT three months after radiation treatment. The patient exhibited no signs of pneumonitis on the last radiological follow-up examination six months after radiotherapy. The reduced dyspnea and cough over the first four months after treatment were observed.

In conclusion, tumor shrinkage and temporary clinical improvement of the patient as well as no technical complications of implanted cardiac devices were achieved by the radiation treatment.

Stereotactic body radiotherapy for centrally located stage I NSCLC: a multicenter analysis

PURPOSE

The purpose of this work is to analyze patterns of care and outcome after stereotactic body radiotherapy (SBRT) for centrally located, early-stage, non-small cell lung cancer (NSCLC) and to address the question of potential risk for increased toxicity in this entity.

METHODS AND MATERIALS

A total of 90 patients with centrally located NSCLC were identified among 613 cases in a database of 13 German and Austrian academic radiotherapy centers. The outcome of centrally located NSCLC was compared to that of cases with peripheral tumor location from the same database.

RESULTS

Patients with central tumors most commonly presented with UICC stage IB (50 %), while the majority of peripheral lesions were stage IA (56 %). Average tumor diameters were 3.3 cm (central) and 2.8 cm (peripheral). Staging PET/CT was available for 73 and 74 % of peripheral and central tumors, respectively. Biopsy was performed in 84 % (peripheral) and 88 % (central) of cases. Doses varied significantly between central and peripheral lesions with a median BED10 of 72 Gy and 84 Gy, respectively (p < 0.001). Fractionation differed as well with medians of 5 (central) and 3 (peripheral) fractions (p < 0.001). In the Kaplan-Meier analysis, 3-year actuarial overall survival was 29 % (central) and 51 % (peripheral; p = 0.004) and freedom from local progression was 52 % (central) and 84 % (peripheral; p < 0.001). Toxicity after treatment of central tumors was low with no grade III/IV and one grade V event. Mortality rates were 0 and 1 % after 30 and 60 days, respectively.

CONCLUSION

Local tumor control in patients treated with SBRT for centrally located, early-stage NSCLC was favorable, provided ablative radiation doses were prescribed. This was, however, not the case in the majority of patients, possibly due to concerns about treatment-related toxicity. Reported toxicity was low, but prospective trials are needed to resolve the existing uncertainties and to establish safe high-dose regimens for this cohort of patients.

External radioactive markers for PET data-driven respiratory gating in positron emission tomography

PURPOSE

Respiratory gating is an established approach to overcoming respiration-induced image artefacts in PET. Of special interest in this respect are raw PET data-driven gating methods which do not require additional hardware to acquire respiratory signals during the scan. However, these methods rely heavily on the quality of the acquired PET data (statistical properties, data contrast, etc.). We therefore combined external radioactive markers with data-driven respiratory gating in PET/CT. The feasibility and accuracy of this approach was studied for [(18)F]FDG PET/CT imaging in patients with malignant liver and lung lesions.

METHODS

PET data from 30 patients with abdominal or thoracic [(18)F]FDG-positive lesions (primary tumours or metastases) were included in this prospective study. The patients underwent a 10-min list-mode PET scan with a single bed position following a standard clinical whole-body [(18)F]FDG PET/CT scan. During this scan, one to three radioactive point sources (either (22)Na or (18)F, 50-100 kBq) in a dedicated holder were attached the patient's abdomen. The list mode data acquired were retrospectively analysed for respiratory signals using established data-driven gating approaches and additionally by tracking the motion of the point sources in sinogram space. Gated reconstructions were examined qualitatively, in terms of the amount of respiratory displacement and in respect of changes in local image intensity in the gated images.

RESULTS

The presence of the external markers did not affect whole-body PET/CT image quality. Tracking of the markers led to characteristic respiratory curves in all patients. Applying these curves for gated reconstructions resulted in images in which motion was well resolved. Quantitatively, the performance of the external marker-based approach was similar to that of the best intrinsic data-driven methods. Overall, the gain in measured tumour uptake from the nongated to the gated images indicating successful removal of respiratory motion was correlated with the magnitude of the respiratory displacement of the respective tumour lesion, but not with lesion size.

CONCLUSION

Respiratory information can be assessed from list-mode PET/CT through PET data-derived tracking of external radioactive markers. This information can be successfully applied to respiratory gating to reduce motion-related image blurring. In contrast to other previously described PET data-driven approaches, the external marker approach is independent of tumour uptake and thereby applicable even in patients with poor uptake and small tumours.

Survivin, a target to modulate the radiosensitivity of Ewing's sarcoma

BACKGROUND AND PURPOSE

Radiotherapy constitutes an essential element in the multimodal therapy of Ewing's sarcoma. Compared to other sarcomas, Ewing tumors normally show a good response to radiotherapy. However, there are consistently tumors with a radioresistant phenotype, and the underlying mechanisms are not known in detail. Here we investigated the association between survivin protein expression and the radiosensitivity of Ewing's sarcoma in vitro.

MATERIAL AND METHODS

An siRNA-based knockdown approach was used to investigate the influence of survivin expression on cell proliferation, double-strand break (DSB) induction and repair, apoptosis and colony-forming ability in four Ewing's sarcoma cell lines with and without irradiation.

RESULTS

Survivin protein and mRNA were upregulated in all cell lines tested in a dose-dependent manner. As a result of survivin knockdown, STA-ET-1 cells showed reduced cell proliferation, an increased number of radiation-induced DSBs, and reduced repair. Apoptosis was increased by knockdown alone and increased further in combination with irradiation. Colony formation was significantly reduced by survivin knockdown in combination with irradiation.

CONCLUSION

Survivin is a radiation-inducible protein in Ewing's sarcoma and its down-regulation sensitizes cells toward irradiation. Survivin knockdown in combination with radiation inhibits cell proliferation, repair, and colony formation significantly and increases apoptosis more than each single treatment alone. This might open new perspectives in the radiation treatment of Ewing's sarcoma.

Retrospective, monocentric analysis of late effects after Total Body Irradiation (TBI) in adults

PURPOSE

Total body irradiation (TBI) is a standard treatment modality within the multidisciplinary approach for allogeneous stem cell or bone marrow transplantation. However, surviving patients are at risk for developing a variety of late sequelae. This analysis aimed to retrospectively characterize late effects after TBI in adults treated in a single center.

PATIENTS AND METHODS

Patients ≥ 18 years treated with fractionated TBI (4-12 Gy) between 1996 and 2008 were included in this study. Treatment data were collected retrospectively from the treating departments. Late effects were evaluated using the clinic charts and/or were obtained from the general practitioners using a standardized questionnaire. Analyses were performed by calculation of the cumulative incidences using the Kaplan-Meier method and the log rank test.

RESULTS

A total of 308 patients ≥ 18 years were treated including a TBI of whom 78 patients were excluded from further analysis due to death within less than 1 year after TBI. Patients suffered from leukemia in most cases. Late toxicity follow-up was available in 120 patients (mean age 46.1 years; range, 18-70 years) after a mean follow-up of 23 months (range, 12-96 months). The cumulative incidences (CI) at 3 years were 28% for pulmonary event, 8% for pulmonary toxicity, 25% for kidney toxicity, 8% for cataract, 17% for bone toxicity, and 10% for secondary malignancy. The CI of bone toxicity was higher in female than in male patients (p = 0.019).

CONCLUSION

Late effects after TBI in the context of allogeneous stem cell or bone marrow transplantation can frequently be observed. Regular follow-up examinations are advised for the early registration and treatment of adverse effects.

Heterogeneity of radiation- and TNF-alpha-induced programmed cell death in carcinoma, sarcoma and lymphoma cell lines

AIM

To characterize the interaction of tumour necrosis factor alpha (TNF-alpha) and ionising radiation in six sarcoma, lymphoma and carcinoma cell lines.

MATERIALS AND METHODS

Cells were characterized regarding annexin V/propiduim iodine affinity and caspase-3 status after application of TNF-alpha, radiation, or combined treatment.

RESULTS

Three cell lines showed similar results with additive effects of TNF-alpha and radiation in both assays. The other three cell lines significantly differed regarding the detection of apoptotic cells between treatment conditions (radiation and/or TNF application) and between the two apoptosis assays.

CONCLUSION

The interaction between TNF-alpha and radiation differs between tumour entities and cannot be described by using only one parameter.

Late effects of abdominal irradiation in children: a review of the literature

AIM

To comprehensively summarize the most important literature regarding the late effects of radiotherapy to the abdomen in childhood and adolescence.

MATERIALS AND METHODS

Published trials, studies and series were identified using the PubMed database. The key words late effects, late sequelae, child, radiation, radiotherapy, abdomen, kidney, liver, and bowel were used.

RESULTS

A dose-volume effect is confirmed for liver irradiation. Radiation with doses <20 Gy to major parts of the liver or higher doses to smaller parts seems to be safe. Kidney function impairment due to radiation is rare in children. Renal sequelae may occur after radiation to the remaining kidney in patients who underwent nephrectomy or who received higher doses to both kidneys. Several reports describe small bowel obstruction as a sequelae of surgery, but radiotherapy seems to be less important.

CONCLUSION

Several retrospective reports describe radiation-associated late sequelae in children. However, there is still a lack of sufficient data regarding the characterization of dose-volume effects.

Kidney-autotransplantation before radiotherapy: a case report

BACKGROUND

A 28-year-old man suffering from a Ewing tumour arising from the 9th-11th ribs with infiltration of neuroforamina without distant metastases was planned to receive radiotherapy following primary intralesional surgery and induction chemotherapy. Due to pleural infiltration and effusion, a hemithorax irradiation with a sequential boost to the primary tumour site had to be administered. Different treatment planning variants failed to provide sufficient radiotherapy planning in view of target volume coverage and avoidance of organs at risk, especially due to high calculated radiation doses potentially compromising the left kidney.

MATERIALS AND METHODS

To prevent left kidney organ exposure, an autotransplantation of the left kidney into the right fossa iliaca was performed. An infiltration of the kidney was initially excluded.

RESULTS

Postoperatively, a renal scintigraphy showed a normal function of both kidneys allowing sufficient radiotherapy treatment planning. Target volume coverage was easily obtained using a combination of hemithorax irradiation and a sequential boost by an intensity-modulated-radiotherapy technique.

CONCLUSION

In difficult individual treatment situations, surgical transpositions as well as organ autotransplantation might be useful in reducing radiotherapy organ dose levels.

Medical and health economic assessment of radiosurgery for the treatment of brain metastasis

Background

Radiotherapy for patients suffering from malignant neoplasms has developed greatly during the past decades. Stereotactic radiosurgery (SRS) is one important radiotherapeutic option which is defined by a single and highly focussed application of radiation during a specified time interval. One of its important indications is the treatment of brain metastases.

Objectives

The objective of this HTA is to summarise the current literature concerning the treatment of brain metastasis and to compare SRS as a single or additional treatment option to alternative treatment options with regard to their medical effectiveness/efficacy, safety and cost-effectiveness as well as their ethical, social and legal implications.

Methods

A structured search and hand search of identified literature are performed from January 2002 through August 2007 to identify relevant publications published in English or German. Studies targeting patients with single or multiple brain metastases are included. The methodological quality of included studies is assessed according to quality criteria, based on the criteria of evidence based medicine.

Results

Of 1,495 publications 15 medical studies meet the inclusion criteria. Overall study quality is limited and with the exception of two randomized controlleed trials (RCT) and two meta-analyses only historical cohort studies are identified. Reported outcome measures are highly variable between studies. Studies with high methodological quality provide evidence, that whole-brain radiotherapy (WBRT) in addition to SRS and SRS in addition to WBRT is associated with improved local tumour control rates and neurological function. However, only in patients with single brain metastasis, RPA-class 1 (RPA = Recursive partitioning analysis) and certain primary tumour entities, this combination of SRS and WBRT is associated with superior survival compared to WBRT alone. Studies report no significant differences in adverse events between treatment groups. Methodologically less rigorous studies provide no conclusive evidence with regard to medical effectiveness and safety, comparing SRS to WBRT, neurosurgery (NS) or hypofractionated radiotherapy (HCSRT). The quality of life is not investigated in any of the studies.

Within the searched databases a total of 320 economic publications are identified. Five publications are eligible for this report. The five reports have a quiet variable quality. Concerning the economic efficiency of alternative equipment, while assuming equal effectiveness, the calculations show, that economic efficiency depends to a large extend on the number of patients treated. In case the two alternative equipments are used solely for SRS, the Gamma Knife might be more cost-efficient. Otherwise an adapted linear accelerator is most likely to be beneficial because of its flexibility. One Health Technology Assessment (HTA) states, that the cost for a Gamma Knife and a dedicated linear accelerator are comparable, while an adapted version is cheaper.

No reports concerning ethical, legal and social aspects are identified.

Discussion

Overall, quantity and quality of identified studies is limited. However, the identified studies indicate that the prognosis of patients with brain metastases is despite highly developed and modern treatment regimes still limited. Conclusive evidence with regard to the effectiveness of identified interventions is only available for the combined treatment of SRS and WBRT compared to SRS or WBRT alone. Furthermore, there is insufficient evidence to compare SRS with WBRT, NS or HCSRT.

The efficiency of the different equipments depends to a great extent on the number and the indications of the patients treated. If dedicated systems are used to their full capacity, there is some evidence for superior cost-effectiveness. If more treatment flexibility is required, adapted systems seem to be advantageous. However, equal treatment effectiveness is a necessary assumption for these conclusions. The need for a treatment precision can influence the purchase decision. No reports concerning more recent therapeutic alternatives are currently available.

Conclusion

Combination of SRS and WBRT is associated with improved local tumour control and neurological function compared to SRS or WBRT alone. However, only for patients with single metastasis there is strong evidence that this results in improved survival compared to WBRT alone. Methodologically rigorous studies are warranted to investigate SRS compared to WBRT and NS and to investigate the quality of life in patients undergoing these treatment regimes.

Concerning the type of equipment used, economic efficiency depends to a great extend on the capacity at which the system can be used. Dedicated systems might be favourable for a high number of patients, while lower patient counts probably favour adapted systems with their superior treatment flexibility. Using the equipment at its full capacity may result in a limited number of machines, what in turn may give rise to the question of an equal and easy access to this technology. Studies focusing on the comparative effectiveness and cost-effectiveness of different treatment options and their combinations, especially for the German setting, are warranted.

Perioperative high-dose rate brachytherapy using a bendy applicator (flab): treatment results of 74 patients

BACKGROUND

Radiotherapy plays a pivotal role in tumor treatment. Brachytherapy as an additional radiation technique allows local dose increments in areas at high risk of local failure.

PATIENTS AND METHODS

Our past 15-year experience with tissue-equivalent bendy applicator brachytherapy at the University Hospital Münster, Germany was reviewed. A series of 74 consecutive patients who had mainly been treated for sarcomas with perioperative brachytherapy was analyzed with a focus on local relapse-free survival and side-effects.

RESULTS

The 5-year local control rate was 73% in primary treatment situations with a significant influence of additional external irradiation, surgical margin depth and tumor entity. Late sequelae of combined modality treatment were observed in 40 patients (54%) and mainly concerned wound healing (n = 18, 24%).

CONCLUSION

A high-risk collective, in view of local failure, showed adequate local control rates as well as acceptable late sequelae. Flab brachytherapy is a good treatment option to achieve local radiation dose increments in patients at high risk of local failure.

National aquatic animal health plans: the Australian experience

Following a major pilchard (Sardinops sagax) mortality event in 1995, Australia recognised the need for a national approach to aquatic animal health, particularly with respectto disease response. Cooperation between industry and government led to the development of AQUAPLAN, Australia's National Strategic Plan for Aquatic Animal Health. Under AQUAPLAN, institutional arrangements for the national technical response to aquatic animal health emergencies were developed based on existing arrangements for terrestrial animal health. The number and range of Australian Aquatic Veterinary Emergency Plan (AQUAVETPLAN) manuals are rising steadily; these are manuals that outline Australia's approach to national disease preparedness and propose the technical response and control strategies to be activated. Additional resources include standard diagnostic techniques and a disease field identification guide. Simulation exercises provide training to respond to aquatic emergency animal disease events. While resource issues and addressing governance remain priorities for the further implementation of AQUAPLAN, the highest priority is the development of a formal arrangement between governments and private sectors on the response to an aquatic emergency animal disease event.

[Stereotactic body radiotherapy (SBRT) -- an overview under special consideration of SBRT and LITT in the therapy of liver metastases]

Stereotactic body radiotherapy (SBRT) is a high dose radiotherapy, the radiation dose is applicated one-time or in a few fractions exactly to the tumor or metastases under maximal separation from the normal tissue. Because of this a major expenditure of medical and technical efforts are necessary, a detailed description of the proceedings is following in the methodic part of this article. Indications of SBRT are especially medical irresectable lung tumors of early stages, primary liver/biliary tumors and pulmonary or liver metastases if there is an oncological benefit for the patients. The side effects are moderate, the local tumor control rate is between 78 to 100 %. Depending on the primary tumor the overall survival is prolonged statistically significant. In the Klinikum Krefeld indications of SBRT vs chemotherapy, LITT or resection are discussed by an interdisciplinary conference of gastroenterologists/oncologists, radiologists, radiooncologists and surgeons. An example of LITT will be shown also.

Effects of the gill monogenean Zeuxapta seriolae (Meserve, 1938) and treatment with hydrogen peroxide on pathophysiology of kingfish, Seriola lalandi Valenciennes, 1833

Infections by the gill fluke Zeuxapta seriolae are a serious concern for sea cage aquaculture of kingfish, Seriola lalandi. The present study aimed to determine the pathophysiological effects of a progressive infection with Z. seriolae and the effects of treatment with hydrogen peroxide. For the progression of infection study, infected fish were taken from a sea cage farm, treated to remove parasites and then infected by cohabitation with heavily infected fish. Samples were taken at 2-week intervals for 8 weeks. Infection intensity peaked at 4 weeks post-infection (mean intensity 565.9) and the number of mature worms (2 mm fixed length or larger) peaked at 6 weeks post-infection. Attachment of Z. seriolae appeared to cause little localized pathology; however, the occurrence of hyperplastic lamellae increased as the infection progressed. Haemoglobin concentrations were negatively correlated with Z. seriolae intensity and were lower than controls at 4 weeks (35.8% decrease) and 6 weeks (57.4% decrease) post-infection. Blood lactate concentration and plasma osmolality increased throughout the course of infection. For the effect of treatment experiment, groups of infected and non-infected fish were sampled either before or after treatment with hydrogen peroxide. Treated fish from both infected and uninfected groups had increased plasma lactate, osmolality and pH compared with pre-treatment groups. Treatment with hydrogen peroxide appeared to have acute effects on fish health but the magnitude (e.g. lactate, osmolality) and extent of the effects (e.g. haemoglobin) was much less than that caused by chronic infection with Z. seriolae.