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to explore the feasibility and effectiveness of para-split laminotomy in the treatment of lumbar intraspinal tumors.We retrospectively review the clinical data of 15 patients suffering lumbar intraspinal tumors, who underwent tumor resection using the para-split laminotomy, from October 2016 to May 2018. Observation indicators were as follows: (1) surgical and postoperative recovery situations; (2) the neurological function of the spinal cord and the follow-up situations.Mean blood loss was 95.3 ± 58.2 ml, and the mean duration of the surgical procedure was 176.7 ± 35.2 min. All lumbar intraspinal tumors were resected completely. There were no operative complications. The postoperative CT scans showed no pedicle or vertebral fractures. During the follow-up period of 6-18 months (average 10.8 ± 3.9 months), no tumor recurrence or spinal deformation was found according to the imaging examination. CT 3D reconstructions showed that the split laminae tended to heal. The average preoperative JOA score was 15.5 ± 4.9 and the average postoperative JOA score improved to 24.0 ± 3.5 (average improvement rate 65.9 ± 19.6%).The para-split laminotomy could reduce the damage to the posterior spinal tension band and help to protect the stability of the spine. It is feasible and effective to apply the para-split laminotomy to the operation of a lumbar intraspinal tumor, and this technique may be a promising option when considering surgical methods for some multilevel well-circumscribed intraspinal tumors.

To analyze the distribution pattern of lymph nodes (LNs) metastasis of level Ib in nasopharyngeal cancer (NPC) and propose shrinkage of clinical target volume (CTV) boundaries to avoid unnecessary radiation for some space with very low-risk of involvement.Pretreatment images of pathologically proven NPC patients were reviewed and those with positive level Ib LN metastasis was enrolled. The geometric center of each level Ib LN in the neck was marked on a template CT. The spatial relationship of nodes with key structures in level Ib was analyzed. Modified level Ib CTV according to the 2013 International CTV consensus was proposed based on the LN distribution pattern. A PlanIQ Feasibility DVH module was implemented to evaluate the feasibility analysis of the best possible sparing of organs at risk (OAR) with modified Ib CTV.A total of 1518 NPC patients were reviewed and 54 with positive level Ib nodes were enrolled. Four sub-level anatomical regions were defined within the gross area of level Ib. Of 106 positive nodes identified, none, one, 88, and 17 were found in the intraglandular (IG), medial mandibular (MM), supra perivascular (SP), and infra perivascular (IP) sub-level, respectively. This study proposes sparing the IG and MM sub-level and including the area within a specified distance from the submandibular gland (11 mm for SP, 17 mm for IP) for CTV coverage. Compared with planning based on CTV-consensus, planning based on CTV-proposed results in a significantly reduced CTV volume, and mean dose (DBased on detailed analysis of the relationship between positive node distribution and several important anatomical structures, modified level Ib CTV for prophylactic irradiation was proposed to reduce the dose of OAR irradiation.

Objectives: In breast radiotherapy, the proximity of the target to sensitive structures together with the uncertainty introduced by respiratory movement, make this treatment one of the most studied to increase its effectiveness. Dosimetric and physical variables play an important role and the study of their correlation and impact on treatment is fundamental. This retrospective study aims to highlight the dosimetric differences of 2 different clinical data sets of patients receiving left-sided breast irradiation in free breathing (FB) or breath hold (BH). Methods: A total of 155 left breast carcinoma patients receiving whole-breast irradiation in FB (73 patients) and BH (82 patients) were enrolled in this study. The dosimetric parameters of the target, heart, left and right lung and right breast were evaluated and compared, and possible correlations were studied in both groups. Results: No significant difference ( P > .05) was found in the target dosimetry; a clear advantage in BH for both high and low doses received by the heart, with reductions of the dosimetric parameters between 27.1% and 100% ( P

Postmastectomy radiation therapy is technically difficult and can be considered one of the most complex techniques concerning patient setup reproducibility. Slight patient setup variations - particularly when high-conformal treatment techniques are used - can adversely affect the accuracy of the delivered dose and the patient outcome. This research aims to investigate the inter-fraction setup variations occurring in two different scenarios of clinical practice: at the reference and at the current patient setups, when an image-guided system is used or not used, respectively. The results were used with the secondary aim of assessing the robustness of the patient setup procedure in use. Forty eight patients treated with volumetric modulated arc and intensity modulated therapies were included in this study. EPID-based in vivo dosimetry (IVD) was performed at the reference setup concomitantly with the weekly cone beam computed tomography acquisition and during the daily current setup. Three indices were analyzed: the ratio R between the reconstructed and planned isocenter doses, γ % and the mean value of γ from a transit dosimetry based on a two-dimensional γ -analysis of the electronic portal images using 5% and 5 mm as dose difference and distance to agreement gamma criteria; they were considered in tolerance if R was within 5%, γ % > 90% and γ mean < 0.4. One thousand and sixteen EPID-based IVD were analyzed and 6.3% resulted out of the tolerance level. Setup errors represented the main cause of this off tolerance with an occurrence rate of 72.2%. The percentage of results out of tolerance obtained at the current setup was three times greater (9.5% vs 3.1%) than the one obtained at the reference setup, indicating weaknesses in the setup procedure. This study highlights an EPID-based IVD system's utility in the radiotherapy routine as part of the patient's treatment quality controls and to optimize (or confirm) the performed setup procedures' accuracy.

Incidental radiation exposure to the heart during lung cancer radiotherapy is associated with radiation-induced heart disease and increased rates of mortality. By considering the respiratory-induced motion of the heart it is possible to create a radiotherapy plan that results in a lower overall cardiac dose. This approach is challenging using current clinical practices: manual contouring of the heart is time consuming, and subject to inter- and intra-observer variability. In this work, we investigate the feasibility of our previously developed, atlas-based, automatic heart segmentation tool to delineate the heart in four-dimensional x-ray computed tomography (4D-CT) images. We used a dataset comprising 19 patients receiving radiotherapy for lung cancer, with 4D-CT imaging acquired at 10 respiratory phases and with a maximum intensity projection image generated from these. For each patient, one of four experienced radiation oncologists contoured the heart on each respiratory phase image and the maximum intensity image. Automatic segmentation of the heart on these same patient image sets was achieved using a leave-one-out approach, where for each patient the remaining 18 were used as an atlas set. The consistency of the automatic segmentation relative to manual contouring was evaluated using the Dice similarity coefficient (DSC) and mean absolute surface-to-surface distance (MASD). The DSC and MASD are comparable to inter-observer variability in clinically acceptable whole heart delineations (average DSC > 0.93 and average MASD < 2.0 mm in all the respiratory phases). The comparison between automatic and manual delineations on the maximum intensity images produced an overall mean DSC of 0.929 and a mean MASD of 2.07 mm. The automatic, atlas-based segmentation tool produces clinically consistent and robust heart delineations and is easy to implement in the routine care of lung cancer patients.

The goal of this study was to evaluate the use of multi-criteria optimization (MCO) in the planning and optimization of intensity-modulated radiotherapy (IMRT). Twenty (20) IMRT patients (ten (10) with prostate cancer and ten (10) with lung cancer) were randomly selected. The treatment plans for these patients were designed using direct machine parameter optimization (DMPO). Based on these plans, new plans were designed using multi-criteria optimization (MCO), keeping the optimization objectives and constraints unchanged. Comparisons were made between the new plans, which were based on MCO and DMPO, including the dose distribution, dose volume histogram (DVH), the optimization time and the number of monitor units (MUs). The plan designed using both optimization approaches satisfied all clinical requirements. For similar or better target coverage, the rectum, bladder and small bowel were better protected using MCO than when using DMPO. Additionally, MCO reduced the time for optimization by 58% on average, whereas the MUs increased the time for optimization by 32% on average for prostate cancer. For lung cancer cases, the entire lung, heart and spinal cord were better protected using MCO compared to DMPO. Similarly, MCO reduced the time for optimization by 59% on average, whereas the MUs increased the time for optimization by 11% on average. Compared to DMPO, MCO reduces the dose of the organs at risk (OAR) and shortens the time required for optimization.

Background Volumetric modulated arc therapy (VMAT) adopted in post-mastectomy radiation therapy (PMRT) has the capacity to achieve highly conformal dose distributions. The research aims to evaluate the impact of positioning errors in the dosimetry of VMAT left-sided PMRT. Methods A total of 18 perturbations where introduced in 11 VMAT treatment plans that shifted the isocenter from its reference position of 3, 5, 10 mm in six directions. The thoracic wall and supraclavicular clinical target volumes (CTVs), the heart and the left lung dose volume histograms (DVHs) of 198 perturbed plans were calculated. The absolute differences (∆) of the mean dose (Dm) and DVH endpoints Vx and Dy (percentage volume receiving x Gy, and dose covering y% of the volume, respectively) were used to compare the dosimetry of the reference vs perturbed plans. Results Isocenter shifts in the anterior and lateral directions lead to maximum disagreement between the CTVs dosimetry of perturbed vs reference plans. Isocenter shifts of 10 mm shown a decrease of D95, D98 and Dm of 12.8, 18.0, and 2.9% respectively, for the CTVs. For 5 mm isocenter shifts, these differences decreased to 3.2, 5.2, and 0.9%, respectively, and for 3 mm shifts to 1.0, 1.7, and 0.6%, respectively. For the organs at risk (OARs), only isocenter shifts in the right, posterior and inferior directions worsen the plan dosimetry, nevertheless not negligible lung ∆ V20 of + 2.6%, and heart ∆ V25 of + 1.6% persist for 3 mm shifts. Conclusions Inaccuracy in isocenter positioning for VMAT left-sided PMRT irradiation may impact the dosimetry of the CTVs and OARs to a different extent, depending on the directions and magnitude of the perturbation. The acquired information could be useful for planning strategies to guarantee the accuracy of the treatment delivered.

As deep sub-micron technologies advance, architectures of microprocessors have evolved from traditional monolithic ones into parallel ones which consist of large number of small but energy efficient cores that rely on Network-on-Chip (NoC) communication infrastructure to achieve scalability. This thesis presents the design and development of a comprehensive simulation framework for an NoC based system simulator covering all system levels from low-level hardware modules to high-level software applications. The motivation stems from the fact that there exists no publicly available simulator that supports embedded NoC based manycore systems. A cycle-level simulation framework has been proposed using the UNISIM environment to complement the configurable on-chip network built upon efficient pipelined routers that employ wormhole switching and virtual-channel flow control. In order to accelerate the cycle-level micro-architectural simulations for manycore systems, novel techniques have been devised to accelerate the cycle-level simulations on multi-core platforms. In particular, we have exploited the fine-grained parallelism within each simulated cycle using Pthreads, leading to notable speedups. The proposed multithreaded simulation engine exploits inherent parallelism with the help of an adaptive technique for managing the computation workload and relies on a graph partitioning based technique for automating load balancing among workloads of multithreaded executions. Our investigations show that, by adaptive distribution of modules among multiple CPU cores of the simulation platform at runtime, the proposed techniques can provide for up to 6X speed up using an 8-core computer. Existing allocation strategies do not lend well NoC based many-core systems when their core counts increase. In this thesis, a runtime resource management strategy has been proposed to overcome these limitations thereby making it suitable for NoC based manycore systems that must support a large number of cores. The proposed resource management strategy relies on submesh based scheme for organizing resources at runtime allocation/deallocation process. It employs a hierarchical-based resource allocation and deallocation scheme to speed-up and to save energy. DOCTOR OF PHILOSOPHY (SCE)

Acute skin toxicity observed in radiotherapy treatment of head and neck cancer is a big concern. The purpose of this work is to evaluate the feasibility of a skin dose reduction in the treatment of nasopharyngeal carcinoma without compromising the overall plan quality. This research focused on comparison of the skin dose reduction that can be obtained for the main high conformal radiotherapy delivery techniques. Sixteen cases of early-stage nasopharyngeal carcinoma were included in this study. For each case, a dynamic intensity-modulated radiation therapy, a volumetric modulated arc therapy, and a helical tomotherapy treatment plans were performed with and without the skin as a sensitive structure in the inverse plan optimization. The dosimetric results obtained for the different treatment techniques and plan optimizations were compared. Dose-volume histogram cutoff points of D95%, D98%, and the homogeneity index were used for target comparison, while Dmean and Dmax/D1cc were used for the organs at risk. The skin volume receiving 5 Gy and then 10 to 70 Gy of radiation dosage registered at step of 10 Gy and Dmean were used for the skin dose comparison. One-way analysis of variance was used to assess the dosimetric results obtained for the different types of treatment plans and techniques investigated. A total of 96 treatment plans were analyzed. When the neck skin was considered in the treatment optimization process, the skin volume that received more than 30 Gy was reduced by 3.7% for dynamic intensity modulated, 4.1% for volumetric modulated arc, and 4.3% for dynamic intensity modulated, while the target dose coverage and organs at risk dosages remained unvaried ( p > .05).

Purpose: To evaluate planning quality and dosimetric differences of clinically deliverable Intensity-modulated Radiation Therapy lung plans generated from Tomotherapy, Pinnacle3, and RayStationTM treatment planning systems. Method and Materials: Ten patients diagnosed with non-small-cell lung carcinoma (NSCLC) previously treated with plans on Pinnacle using Direct Machine Parameter Optimization were randomly selected and re-planned with Tomotherapy dose volume constraints and same beam geometry with RayStation Multi Criteria Optimization (MCO) equivalent uniform dose (EUD) or dose volume constraints, respectively. Prescription was established as 60 Gy to cover > 95% of PTV. Planning outcomes such as D95 (95% of volume of PTV receiving the prescribed dose), D5, D33, mean heart and lung doses, V20 (volume of lung receiving 20 Gy), and max cord dose of 1cm3 were evaluated according to our departmental clinical protocols. Conformity index (CI = PTV / prescription isodose volume) and homogeneity index (HI = D5/D95) were also reported simultaneously. All plans were successfully uploaded for delivery verification. Results: Mean volume of calculated PTV was 356 ± 141 cm3. The planning results indicated that CI, HI, D95 and D5 of PTV, V20 of lung, and 1cm3 max cord dose were comparable but with better overall dosimetric distributions with conformity and homogeneity index from Tomotherapy plans in comparison to both Pinnacle and RayStation planning outcomes. Conclusions: Tomotherapy plans achieved better uniform tumor coverage with fewer hot spots while sparing more critical structures with superior dose fall-off. RayStation plans with MCO automatically generated a set of Pareto optimized solutions with given objectives to allow tradeoffs between targets and critical organs and tended to achieve better tumor coverage compared to Pinnacle. All three planning algorithms can generate clinical deliverable IMRT lung plans while Tomotherapy plans provide superior dosimetric indexes compared to Pinnacle and RayStation due to its unique beamlet optimization process with high modulation.

To evaluate the Elekta kilovoltage CBCT doses and the associated technical protocols with patient dosimetry estimation. Image guidance technique with cone-beam CT (CBCT) in radiation oncology on a daily basis can deliver a significant dose to the patient. To evaluate the patient dose from LINAC-integrated kV cone beam CT imaging in image-guided radiotherapy. CT dose index (CTDI) were measured with PTW TM30009 CT ion chamber in air, in head phantom and body phantom, respectively; with different combinations of tube voltage, current, exposure time per frame, collimator and gantry rotation range. Dose length products (DLP) were subsequently calculated to account for volume integration effects. The CTDI and DLP were also compared to AcQSim™ simulator CT for routine clinical protocols. Both CTDIair and CTDIw depended quadratically on the voltage, while linearly on milliampere x seconds (mAs) settings. It was shown that CTDIw and DLP had very close relationship with the collimator settings and the gantry rotation ranges. Normalized CTDIw for Elekta XVI™ CBCT was lower than that of ACQSim simulator CT owing to its pulsed radiation output characteristics. CTDIw can be used to assess the patient dose in CBCT due to its simplicity for measurement and reproducibility. Regular measurement should be performed in QA & QC program. Optimal image parameters should be chosen to reduce patient dose during CBCT.

In this paper, an ultra-low-energy biomedical signal processor (BSP) is proposed for wireless multi-channel physiological signal monitoring. This BSP integrates a RISC core and application-specific hardware accelerators (ASHAs) to achieve ultra low power consumption while meeting required performance. Various low power design techniques from system to circuit levels are applied, including event-driven signal processing, dynamic clock management, near-threshold operation, glitch-free clock generation, fine-grain clock gating, and ultra-low-voltage level shifting. The BSP can operate with supply from 1.8V down to 0.5V. With integrated ECG ASHAs based on the discrete wavelet transform, its overall energy consumption is 20.4pJ/cycle at 0.5V and 10MHz when performing a real-time wireless ECG monitoring.

Centralized resource management and communication contentions among applications limit the scalability of the existing resource management strategies on NoC-based manycore systems. A scalable hierarchical strategy is proposed in this paper to overcome the above limitation.

Existing resource management strategies for embedded NoCs have limitations due to their adopted non-preemptive multitasking approach. This paper proposes a hybrid multitasking technique in order to overcome the above limitations.

On-line megavoltage computed tomography (MVCT) images are used to verify patient daily set-up in Hi-ART helical TomoTherapy unit. To evaluate the patient dose from MVCT scanning in image guidance, weighted computed tomography (CT) dose index (CTDIw) was measured with PTW TM30009 CT pencil chamber in head and body phantoms for slice thicknesses of 2, 4 and 6 mm with different scan lengths. Dose length products (DLPs) were subsequently calculated. The CTDIw and DLP were compared with XVI kV CBCT and Brilliance simulator CT for routine clinical protocols. It was shown that CTDI and DLP had close relationship with the slice thickness and the scan length. The dose distribution in the transversal plane was very inhomogeneous due to the attenuation of the couch. Patient dose from MVCT was lower than XVI CBCT for the head scan, while larger for body scan. CTDIw, which is measured easily and reproducibly, can be used to assess the patient dose in MVCT. Regular measurement should be performed in QA & QC programmes. Appropriate slice thickness and scan range should be chosen to reduce the patient dose.

Background: The accuracy of dose calculation is crucial to the quality of treatment planning and, consequently, to the dose delivered to patients undergoing radiation therapy. Current general calculation algorithms such as Pencil Beam Convolution (PBC) and Collapsed Cone Convolution (CCC) have shortcomings in regard to severe inhomogeneities, particularly in those regions where charged particle equilibrium does not hold. The aim of this study was to evaluate the accuracy of the PBC and CCC algorithms in lung cancer radiotherapy using Monte Carlo (MC) technology. Methods and materials: Four treatment plans were designed using Oncentra Masterplan TPS for each patient. Two intensity-modulated radiation therapy (IMRT) plans were developed using the PBC and CCC algorithms, and two three-dimensional conformal therapy (3DCRT) plans were developed using the PBC and CCC algorithms. The DICOM-RT files of the treatment plans were exported to the Monte Carlo system to recalculate. The dose distributions of GTV, PTV and ipsilateral lung calculated by the TPS and MC were compared. Result: For 3DCRT and IMRT plans, the mean dose differences for GTV between the CCC and MC increased with decreasing of the GTV volume. For IMRT, the mean dose differences were found to be higher than that of 3DCRT. The CCC algorithm overestimated the GTV mean dose by approximately 3% for IMRT. For 3DCRT plans, when the volume of the GTV was greater than 100 cm 3 , the mean doses calculated by CCC and MC almost have no difference. PBC shows large deviations from the MC algorithm. For the dose to the ipsilateral lung, the CCC algorithm overestimated the dose to the entire lung, and the PBC algorithm overestimated V20 but underestimated V5 ;t he difference in V10 was not statistically significant. Conclusions: PBC substantially overestimates the dose to the tumour, but the CCC is similar to the MC simulation. It is recommended that the treatment plans for lung cancer be developed using an advanced dose calculation algorithm other than PBC. MC can accurately calculate the dose distribution in lung cancer and can provide a notably effective tool for benchmarking the performance of other dose calculation algorithms within patients.