MRI-guidance for motion management in external beam radiotherapy: current status and future challenges.

High precision conformal radiotherapy requires sophisticated imaging techniques to aid in target localisation for planning and treatment, particularly when organ motion due to respiration is involved. X-ray based imaging is a well-established standard for radiotherapy treatments. Over the last few years, the ability of magnetic resonance imaging (MRI) to provide radiation-free images with high-resolution and superb soft tissue contrast has highlighted the potential of this imaging modality for radiotherapy treatment planning and motion management. In addition, these advantageous properties motivated several recent developments towards combined MRI radiation therapy treatment units, enabling in-room MRI-guidance and treatment adaptation. The aim of this review is to provide an overview of the state-of-the-art in MRI-based image guidance for organ motion management in external beam radiotherapy. Methodological aspects of MRI for organ motion management are reviewed and their application in treatment planning, in-room guidance and adaptive radiotherapy described. Finally, a roadmap for an optimal use of MRI-guidance is highlighted and future challenges are discussed.

Independent dose per monitor unit review of eight U.S.A. proton treatment facilities.

PURPOSE: Compare the dose per monitor unit at different proton treatment facilities using three different dosimetry methods. METHODS: Measurements of dose per monitor unit were performed by a single group at eight facilities using 11 test beams and up to six different clinical portal treatment sites. These measurements were compared to the facility reported dose per monitor unit values. RESULTS: Agreement between the measured and reported doses was similar using any of the three dosimetry methods. Use of the ICRU 59 ND,w based method gave results approximately 3% higher than both the ICRU 59 NX and ICRU 78 (TRS-398) ND,w based methods. CONCLUSIONS: Any single dosimetry method could be used for multi-institution trials with similar conformity between facilities. A multi-institutional trial could support facilities using both the ICRU 59 NX based and ICRU 78 (TRS-398) ND,w based methods but use of the ICRU 59 ND,w based method should not be allowed simultaneously with the other two until the difference is resolved.

The current state-of-the-art of spinal cord imaging: methods.

A first-ever spinal cord imaging meeting was sponsored by the International Spinal Research Trust and the Wings for Life Foundation with the aim of identifying the current state-of-the-art of spinal cord imaging, the current greatest challenges, and greatest needs for future development. This meeting was attended by a small group of invited experts spanning all aspects of spinal cord imaging from basic research to clinical practice. The greatest current challenges for spinal cord imaging were identified as arising from the imaging environment itself; difficult imaging environment created by the bone surrounding the spinal canal, physiological motion of the cord and adjacent tissues, and small cross-sectional dimensions of the spinal cord, exacerbated by metallic implants often present in injured patients. Challenges were also identified as a result of a lack of "critical mass" of researchers taking on the development of spinal cord imaging, affecting both the rate of progress in the field, and the demand for equipment and software to manufacturers to produce the necessary tools. Here we define the current state-of-the-art of spinal cord imaging, discuss the underlying theory and challenges, and present the evidence for the current and potential power of these methods. In two review papers (part I and part II), we propose that the challenges can be overcome with advances in methods, improving availability and effectiveness of methods, and linking existing researchers to create the necessary scientific and clinical network to advance the rate of progress and impact of the research.

The current state-of-the-art of spinal cord imaging: applications.

A first-ever spinal cord imaging meeting was sponsored by the International Spinal Research Trust and the Wings for Life Foundation with the aim of identifying the current state-of-the-art of spinal cord imaging, the current greatest challenges, and greatest needs for future development. This meeting was attended by a small group of invited experts spanning all aspects of spinal cord imaging from basic research to clinical practice. The greatest current challenges for spinal cord imaging were identified as arising from the imaging environment itself; difficult imaging environment created by the bone surrounding the spinal canal, physiological motion of the cord and adjacent tissues, and small crosssectional dimensions of the spinal cord, exacerbated by metallic implants often present in injured patients. Challenges were also identified as a result of a lack of "critical mass" of researchers taking on the development of spinal cord imaging, affecting both the rate of progress in the field, and the demand for equipment and software to manufacturers to produce the necessary tools. Here we define the current state-of-the-art of spinal cord imaging, discuss the underlying theory and challenges, and present the evidence for the current and potential power of these methods. In two review papers (part I and part II), we propose that the challenges can be overcome with advances in methods, improving availability and effectiveness of methods, and linking existing researchers to create the necessary scientific and clinical network to advance the rate of progress and impact of the research.

Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom.

OBJECTIVE: The purpose of this study was to evaluate spot scanning proton therapy with an anthropomorphic prostate phantom at the Proton Therapy Center of The University of Texas MD Anderson Cancer Center at Houston, TX (PTCH). METHODS: An anthropomorphic prostate phantom from the Radiological Physics Center (RPC), The University of Texas MD Anderson Cancer Center, Houston, TX, was used, which contained thermoluminescent dosemeters and GAFCHROMIC(®) EBT2 film (ISP Technologies, Wayne, NJ). The phantom was irradiated by the Hitachi synchrotron (Hitachi America, Ltd, Tarrytown, NY), and the results were compared between the treatment planning system (TPS) and RPC measurements. RESULTS: RPC results show that the right/left, inferior/superior and posterior/anterior aspects of the coronal/sagittal and EBT2 film measurements were within ±7%/±4 mm of the TPS. The RPC thermoluminescent dosemeter measurements of the prostate and femoral heads were within 3% of the TPS. CONCLUSION: The RPC prostate phantom is a useful mechanism to evaluate spot scanning beam proton therapy within certain confidence levels. ADVANCES IN KNOWLEDGE: The RPC anthropomorphic prostate phantom could be used to establish quality assurance of spot scanning proton beam for patients with prostate cancer.

SU-E-T-291: Dosimetry of Double Scattered Proton Beam Fields Used for Cranio-Spinal Irradiation.

PURPOSE: To investigate the effect of source to surface distance on treatment field lateral penumbra width and the consequence of setup error on the dose distribution in the junction between two spinal fields of double scattered proton beams. METHODS: The CT images of the Spine Phantom from Radiological Physics Center was used to design a double scattered proton beam treatment plan using Varian Eclipse treatment planning system. PTV included spinal cord, vertebral body and part of spinous process. The PTV was divided into superior and inferior parts and two posterior fields were used to cover the targets with the prescribed dose. 2D dose was measured using IBA MatriXX and EBT2 film at a depth close to the center of SOBPs of both the fields located both at the nominal source to axis distance (SAD) of 270 cm and at an extended SAD. The field separation was changed by ±1 mm to study the effect of setup error. The measured and TPS calculated dose distributions in verification plans in a water phantom were compared. RESULTS: The measured 2-D doses agreed very well with planned ones for individual fields. 99% of pixels pass 3%/3 mm dose/distance agreement criteria. The CAX dose differences are within 2%. The 80% to 20% penumbra widths at nominal SAD are 7.4/7.7/7.8 mm for planned/MatriXX/EBT2 film respectively, and about 1 mm wider for the extended SAD. The measured maximum dose was about 10% higher than that from the plan, and decreased/increased about 7% when the fields were separated by ±1 mm. CONCLUSIONS: The penumbra width is modestly affected by the extended SSD often used for patient treatment. Dose in the junction of two fields is very sensitive to the setup error and the accuracy of the TPS dose calculation in this region may be limited.

SU-E-T-223: High-Energy Photon Standard Dosimetry Data: A Quality Assurance Tool.

PURPOSE: Describe the Radiological Physics Center's (RPC) extensive standard dosimetry data set determined from on-site audits measurements. METHOD AND MATERIALS: Measurements were made during on-site audits to institutions participating in NCI funded cooperative clinical trials for 44 years using a 0.6cc cylindrical ionization chamber placed within the RPC's water tank. Measurements were made on Varian, Siemens, and Elekta/Philips accelerators for 11 different energies from 68 models of accelerators. We have measured percent depth dose, output factors, and off-axis factors for 123 different accelerator model/energy combinations for which we have 5 or more sets of measurements. The RPC analyzed these data and determined the 'standard data' for each model/energy combination. The RPC defines 'standard data' as the mean value of 5 or more sets of dosimetry data or agreement with published depth dose data (within 2%). RESULTS: The analysis of these standard data indicates that for modern accelerator models, the dosimetry data for a particular model/energy are within ï,±2%. The RPC has always found accelerators of the same make/model/energy combination have the same dosimetric properties in terms of depth dose, field size dependence and off-axis factors. Because of this consistency, the RPC can assign standard data for percent depth dose, average output factors and off-axis factors for a given combination of energy and accelerator make and model. CONCLUSIONS: The RPC standard data can be used as a redundant quality assurance tool to assist Medical Physicists to have confidence in their clinical data to within 2%. The next step is for the RPC to provide a way for institutions to submit data to the RPC to determine if their data agrees with the standard data as a redundant check. This work was supported by PHS grants CA10953 awarded by NCI, DHHS.

SU-D-BRCD-01: Evaluation of Zebra Multi-Layer Ionization Chamber System for Patient Treatment Field and Machine QA for Spot Scanning and Passive Scattering Proton Beams.

PURPOSE: To evaluate Zebra multi-layer ionization chamber system for patient treatment field and machine QA for spot scanning proton beams (SSPB) and passive scattering proton beams (PSPB). METHODS: Zebra dose measurement system (IBA Dosimetry), consisting of 180 parallel platechambers with 2 mm detector spacing, was used for measuring proton beamdepth dose curves (DDC) for spread out Bragg peaks (SOBP) and single spot pristine Bragg peaks (PBP). The measurements were performed for 100 to 250 MeV PSPB and 89.2 to 221.8 MeV SSPB using the Hitachi ProBeat synchrotron based delivery system. An in-house Matlab based analysis software was used to compare the Zebra measured DDC with those measured by the Markus chamber in a PTW water tank (MC-WT). Several verification plans in the water phantom were created for patient treatment fields using the Eclipse treatment planning system (TPS). The DDC for individual verification fields were measured using the Zebra andcomparisons were made with the TPS calculations. RESULTS: The dosedifferences between the Zebra and MC-WT measurements in the plateau regions of the DDC are within 2% for various energies of PSPB, but are larger than 2% at the sharp dose distal gradient regions. The values for distal penumbra widths, range and SOBP widths from Zebra and MC-WT measurements agree within 0.5 mm, 1.5 mm, and 2 mm, respectively. The Zebra measured values of the range of the single spots also agreed within 1 mm with their established values from other measurements. The Zebra measured DDC of verification plan of patient treatment fields showed goodagreement with those from the TPS. CONCLUSIONS: Our investigation shows that Zebra can be useful for fast and reasonably accurate measurements of the DDC of pristine and spread-out Bragg peaks of both spot scanning and passive scattering proton beams.

MO-D-BRB-02: The Radiological Physics Center's Quality Audit Program: Where Can We Improve?

PURPOSE: To analyze the findings of the Radiological Physics Center's (RPC) QA audits of institutions participating in NCI sponsored clinical trials. METHODS: The RPC has developed an extensive Quality Assurance (QA) program over the past 44 years. This program includes on-site dosimetry reviews where measurements on therapy machines are made, records are reviewed and personnel are interviewed. The program's remote audit tools include mailed dosimeters (OSLD/TLD) to verify output calibration, comparison of dosimetry data with RPC 'standard' data, evaluation of benchmark and patient calculations to verify the treatment planning algorithms, review of institution's QA procedures and records, and use of anthropomorphic phantoms to verify tumor dose delivery. The RPC endeavors to assist institutions in finding the origins of any detected discrepancies, and to resolve them. RESULTS: Ninety percent of institutions receiving dosimetry recommendations has remained level for the past 5 years. The most frequent recommendations were for not performing TG-40 QA tests, wedge factors, small field size output factors and off-axis factors. Since TG-51 was published, the number of beam calibrations audited during visits with ion chambers, that met the RPC's ±3% criterion, decreased initially but has risen to pre-TG-51 levels. The OSLD/TLD program shows that only ∼3% of the beams are outside our ±5% criteria, but these discrepancies are distributed over 12-20% of the institutions. The percent of institutions with ï,3 l beam outside the RPC's criteria is approximately the same whether OSLD/TLD or ion chambers were used. The first time passing rate for the anthropomorphic phantoms is increasing with time. The prostate phantom has the highest pass rate while the spine phantom has the lowest. CONCLUSIONS: Numerous dosimetry errors continue to be discovered by the RPC's QA program and the RPC continues to play an important role in helping institutions resolve these errors. This work was supported by PHS grants CA10953 and CA081647 awarded by NCI.

MO-D-BRB-04: The Approval Process for the Use of Proton Therapy in NCI-Sponsored Clinical Trials.

PURPOSE: To describe the approval process for the use of proton therapy in NCI- sponsored clinical trials. METHODS: The RPC has developed a comprehensive system for the approval of proton therapy centers for participation in clinical trials. The approval process includes: 1) completion of the proton facility questionnaire, 2) participation in the RPC's annual TLD remote audit program, 3) electronic submission of treatment planning data to the Image-Guided Therapy Center (ITC), and 4) successful completion of an on-site dosimetry review visit, including the irradiation of two of the RPC's anthropomorphic proton phantoms (prostate and spine). The on-site audits allow the RPC to review the institution's treatment planning process, from simulation to treatment delivery, as well as their quality assurance practices. The RPC performs a complete set of measurements that tests the CT simulator's CT# vs. RSP conversion curve, treatment planning data, on-board imaging, and treatment delivery. These measurements detect gross errors that might lead to inaccurate proton dose delivery. The review of the institutions' QA procedures allows the RPC to encourage all proton centers to maintain a consistent level of periodic monitoring of their proton therapy delivery. Upon completion of the visit, a full report is written detailing the results from the visit, phantom irradiation, and recommendations for improving their treatment delivery and QA. RESULTS: To date, the RPC has approved seven proton therapy centers for the use of scattered or uniform scanning proton treatment delivery in clinical trials. Results of the phantom irradiations have identified an error in the HU vs RLSP curve. The site visits have identified several lapses in QA procedures, inappropriate HU vs RLSP values, and weaknesses in treatment planning. CONCLUSIONS: The RPC's proton therapy approval process has been developed and has identified areas of improvement for proton centers to use proton therapy in clinical trials. Work supported by grants CA10953, CA059267, and CA81647 (NCI, DHHS).

MO-D-BRB-03: Comparison of Proton Therapy Institutional Data Collected by the RPC.

PURPOSE: To detail and compare data collected during RPC onsite dosimetry review visits at proton therapy centers. METHODS: The RPC has established a complete review process for proton therapy institutions wishing to participate in NCI-funded clinical trials that includes an on-site dosimetry review visit performed by the RPC. During the visit, the RPC takes measurements that include CT# vs. relative stopping power (RSP) conversion, beam output, depth dose, lateral profiles, QA procedure reviews and anthropomorphic phantom irradiations. The RPC reviewed beam output, depth dose and lateral profiles for 5 specific anatomic treatment sites, reference, prostate, lung, brain, and spine as compared to the institution's measured or treatment planning-derived values. In addition, the RPC has compared results from each institution's proton prostate phantom irradiation. RESULTS: All of the institutions visited had RPC/Institution output ratios that ranged between 0.95 - 1.02 where the acceptance criterion was ±5%. For the CT# to RSP comparison, there was a larger variability. Only two institutions agreed within five percent of the recommended values, while the other five institutions had disagreements of up to 20 percent in the high density (high CT number) region of the conversion curve that may have a clinical impact on dose delivery. For the prostate phantom irradiation, 3 institutions failed to meet the RPC's ±7%/4mm acceptance criteria on the initial attempt, but in the end all 7 sites met the criteria. CONCLUSIONS: The proton beam output for 7 proton centers, as measured by the RPC, is comparable (±5%), however, there are large discrepancies in the CT# vs RSP conversion curves used from institution to institution. As a result of the RPC onsite dosimetry review visits, several institutions have modified their procedures and dosimetry parameters to improve proton therapy delivery for NCI funded clinical trials. Work supported by grants CA10953, CA059267, and CA81647 (NCI, DHHS).

Scale Invariant Feature Transform as feature tracking method in 4D imaging: a feasibility study.

We propose the use of Scale Invariant Feature Transform (SIFT) as a method able to extract stable landmarks from 4D images and to quantify internal motion. We present a preliminary validation of the SIFT method relying on expert user identification of landmarks and then apply it to 4D lung CT and liver MRI data. Results demonstrate SIFT capabilities as an operator-independent feature tracking method.

Breast MR with special focus on DW-MRI and DCE-MRI.

The use of magnetic resonance imaging (MRI) for the assessment of breast lesions was first described in the 1970s; however, its wide application in clinical routine is relatively recent. The basic principles for diagnosis of a breast lesion rely on the evaluation of signal intensity in T2-weighted sequences, on morphologic assessment and on the evaluation of contrast enhancement behaviour. The quantification of dynamic contrast behaviour by dynamic contrast-enhanced (DCE) MRI and evaluation of the diffusivity of water molecules by means of diffusion-weighted MRI (DW-MRI) have shown promise in the work-up of breast lesions. Therefore, breast MRI has gained a role for all indications that could benefit from its high sensitivity, such as detection of multifocal lesions, detection of contralateral carcinoma and in patients with familial disposition. Breast MRI has been shown to have a role in monitoring of neoadjuvant chemotherapy, for the evaluation of therapeutic results during the course of therapy. Breast MRI can improve the determination of the remaining tumour size at the end of therapy in patients with a minor response. DCE-MRI and DW-MRI have shown potential for improving the early assessment of tumour response to therapy and the assessment of residual tumour after the end of therapy. Breast MRI is important in the postoperative work-up of breast cancers. High sensitivity and specificity have been reported for the diagnosis of recurrence; however, pitfalls such as liponecrosis and changes after radiation therapy have to be carefully considered.

Diffusion-weighted MR imaging in assessing cervical tumour response to nonsurgical therapy.

PURPOSE: This study was undertaken to assess whether there is a correlation between the response of cervical tumours to nonsurgical therapy (chemo- and/or radiotherapy) and apparent diffusion coefficient (ADC) values. PATIENTS AND METHODS: Seventeen consecutive patients prospectively underwent pelvic magnetic resonance (MR) imaging including diffusion-weighted imaging (DWI) sequences before and after nonsurgical therapy for cervical cancer. A control group of 17 patients without cervical pathology was matched to the study group. Differences in baseline ADC maps between the two groups and within the study group before and after therapy were assessed by nonparametric tests. RESULTS: The diameter and volume of cervical cancers decreased after therapy in 14/17 lesions (responders) and increased in 3/17 lesions (nonresponders). The ADC values of responders increased significantly (p=0.0009). Percent changes in ADC values before and after therapy were higher in responders than nonresponders (p=0.04). There was no significant difference in ADC values between responders and nonresponders at the staging MR examination (p=0.09) and no significant correlation between pretreatment ADC values and percentage of tumour reduction. Tumours with higher percent ADC value increase showed higher tumour reduction volume, but this was not significant (p=0.12). CONCLUSIONS: ADC values of cervical cancer after therapy showed significant differences compared with pretherapy values, particularly for responders.

Intraobserver and interobserver variability in the calculation of apparent diffusion coefficient (ADC) from diffusion-weighted magnetic resonance imaging (DW-MRI) of breast tumours.

PURPOSE: This study evaluated intraobserver and interobserver variability in the measurement of apparent diffusion coefficient (ADC) values in breast carcinomas. MATERIALS AND METHODS: Twenty-eight patients with solid breast lesions >10 mm underwent conventional contrast-enhanced magnetic resonance imaging (MRI) and diffusion-weighted MRI (DW-MRI). Two observers (expert and trainee) segmented the lesion from the surrounding breast tissue on DW images with high b-value (1,000 s/mm(2)). This analysis was repeated by the expert reader after 6 months. Volumes were analysed to obtain mean, median and standard deviation (SD) of the ADC values. Interobserver and intraobserver variation was analysed using the Bland-Altman graph. RESULTS: All lesions were breast carcinomas, with a mean ADC value of 1.07 × 10(-3) mm(2)/s. The mean of the differences was 0.012 × 10(-3) mm(2)/s, corresponding to an intraobserver variability of 1.1% (limits of agreement: -5%/+8%). The mean interobserver difference was 0.022 × 10(-3) mm(2)/s, corresponding to an interobserver variability of 2% (limits of agreement: -9%/+14%). CONCLUSIONS: We found a low intraobserver and interobserver variability in calculating ADC in breast carcinomas, which supports its potential use in routine clinical practice.

Rest versus exercise hemodynamics for middle cerebral artery aneurysms: a computational study.

BACKGROUND AND PURPOSE: Exercise is an accepted method of improving cardiovascular health; however, the impact of increases in blood flow and heart rate on a cerebral aneurysms is unknown. This study was performed to simulate the changes in hemodynamic conditions within an intracranial aneurysm when a patient exercises. MATERIALS AND METHODS: Rotational 3D digital subtraction angiograms were used to reconstruct patient-specific geometries of 3 aneurysms located at the bifurcation of the middle cerebral artery. CFD was used to solve for transient flow fields during simulated rest and exercise conditions. Inlet conditions were set by using published transcranial Doppler sonography data for the middle cerebral artery. Velocity fields were analyzed and postprocessed to provide physiologically relevant metrics. RESULTS: Overall flow patterns were not significantly altered during exercise. Across subjects, during the exercise simulation, time-averaged WSS increased by a mean of 20% (range, 4%-34%), the RRT of a particle in the near-wall flow decreased by a mean of 28% (range, 13%-40%), and time-averaged pressure on the aneurysm wall did not change significantly. In 2 of the aneurysms, there was a 3-fold order-of-magnitude spatial difference in RRT between the aneurysm and surrounding vasculature. CONCLUSIONS: WSS did not increase significantly during simulated moderate aerobic exercise. While the reduction in RRT during exercise was small in comparison with spatial differences, there may be potential benefits associated with decreased RRT (ie, improved replenishment of nutrients to cells within the aneurysmal tissue).

Intra- and interobserver agreement and impact of arterial input selection in perfusion CT measurements performed in squamous cell carcinoma of the upper aerodigestive tract.

BACKGROUND AND PURPOSE: CT Perfusion (CTP) has shown potential for assessing head and neck tumors. Our purposes were to assess the inter- and intraobserver agreement of CTP measurements and to investigate whether the selection of arterial input, ipsilateral versus contralateral to the tumor or left-versus-right external carotid artery (ECA), may affect CTP measurements in patients with squamous cell carcinoma (SCCA) of the upper aerodigestive tract. MATERIALS AND METHODS: Twenty-six patients with SCCA were enrolled in this prospective study and underwent CTP. Data were analyzed by 2 expert readers and by an inexperienced reader for interobserver agreement and by the 2 expert readers for intraobserver agreement assessment, by using the ECA ipsilateral to tumor site as arterial input. All 3 readers repeated their analysis by using the ECA contralateral to tumor site as arterial input. Inter- and intraobserver agreement was assessed by using the Bland-Altman approach; CTP measurements by using ipsilateral-versus-contralateral or left-versus-right ECA were compared by using the Wilcoxon signed rank test. RESULTS: The geometric mean of the ratios (95% limits of agreement) for inter- and intraobserver agreement ranged from 0.96 (0.75-1.23) to 1.00 (0.92-1.10) for blood flow (BF), from 0.88 (0.63-1.21) to 1.00 (0.88-1.14) for blood volume (BV), from 0.96 (0.64-1.44) to 0.98 (0.76-1.27) for mean transit time (MTT), and from 0.85 (0.41-1.76) to 1.14 (0.70-1.86) for permeability surface area product (PS). Significantly higher tumor PS and MTT for 2 readers and lower tumor BF for 1 of 3 readers were observed when the arterial input was placed in the left ECA. CONCLUSIONS: BF, BV, and MTT demonstrated higher inter- and intraobserver agreement than PS. The selection of arterial input, right-versus-left ECA, may determine changes in CTP measurements in patients with SCCA of the upper aerodigestive tract.

Computational modelling for cerebral aneurysms: risk evaluation and interventional planning.

Advanced computational techniques offer a new array of capabilities in the healthcare provision for cerebral aneurysms. In this paper information is provided on specific simulation methodologies that address some of the unanswered questions about intracranial aneurysm and their treatment. These include the evaluation of rupture risk, the thrombogenic characteristics of specific lesions and the efficacy assessment of particular interventional techniques and devices (e.g. endovascular coil embolisation and flow diversion using stents). The issues connected with ease-of-use and interactivity of computed simulations is discussed, and it is concluded, that the potential of these techniques to optimise planning of complex and multifaceted interventions is very significant, in spite of the fact that most of the methodologies described are still being developed and perfected.

@neurIST - chronic disease management through integration of heterogeneous data and computer-interpretable guideline services.

This paper presents an overview of computerised decision support for clinical practice. The concept of computer-interpretable guidelines is introduced in the context of the @neurIST project, which aims at supporting the research and treatment of asymptomatic unruptured cerebral aneurysms by bringing together heterogeneous data, computing and complex processing services. The architecture is generic enough to adapt it to the treatment of other diseases beyond cerebral aneurysms. The paper reviews the generic requirements of the @neurIST system and presents the innovative work in distributing executable clinical guidelines.