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Solid-state friction stir welding is a joining technology that allows alloys that are difficult to fuse using traditional fusion methods to be joined. Structures that are not welded are more expensive and heavier, whereas those that are welded are less expensive and lighter. They have benefited from their application due to the difficulty of joining highstrength aerospace aluminium alloys and other metallic alloys using traditional fusion welding. Friction Stir Welding (FSW) produces precipitation-strengthened aluminium alloys with a variety of microstructures and mechanical properties. The chemical composition of an alloy has an impact on its final and initial microstructure. These variables have a significant impact on the weld microstructure and strength, in addition to welding parameters, thermal cycle and the use of auxiliary cooling systems, tool geometry and thickness. FSW, a new green solid state joining method, was used to join high-strength aerospace aluminium alloys. [ABSTRACT FROM AUTHOR]

We compute the model-theoretic Grothendieck ring, K 0 (Q) , of a dense linear order (DLO) with or without end points, Q = (Q , <) , as a structure of the signature { < } , and show that it is a quotient of the polynomial ring over Z generated by N + × (Q ⊔ { - ∞ }) by an ideal that encodes multiplicative relations of pairs of generators. This ring can be embedded in the polynomial ring over Q generated by Q ⊔ { - ∞ } . As a corollary we obtain that a DLO satisfies the pigeon hole principle for definable subsets and definable bijections between them—a property that is too strong for many structures. [ABSTRACT FROM AUTHOR]

The paper focuses on the design of nonlinear state feedback controllers to minimize the amplitude of limit cycle oscillations exhibited by nonlinear aeroelastic systems. Nonlinear normal modes are computed for the closed-loop system to represent the flutter mode dynamics using a single mode. The effectiveness of nonlinear normal modes as a tool to capture the limit cycle oscillation growth is demonstrated. The harmonic balance method is used to estimate the amplitude and frequency of the limit cycle oscillations exhibited by the flutter mode. Analytical estimates of sensitivities of limit cycle amplitude with respect to the introduced control parameters are derived and shown to match closely to the sensitivities computed numerically using the finite difference method on a time marching simulation of the complete aeroelastic system. A multi-objective optimization problem that minimizes the estimate of limit cycle oscillation amplitude and an approximate measure of control cost is solved using the analytical sensitivities. Numerical simulation results are used to verify that minimizing the estimate of the limit cycle amplitude of the flutter nonlinear normal mode corresponds closely to minimizing the simulated limit cycle amplitude of the complete aeroelastic system. [ABSTRACT FROM AUTHOR]

Papillary thyroid carcinoma (PTC) is the most common differentiated thyroid neoplasm. Common sites of regional and distant metastasis includes lymph nodes, lungs and bone. 51 year old female patient who was a known case of PTC with a history of multiple surgeries, radioactive iodine therapy (RAI) and oral chemotherapy presented with a painful right parotid mass. PET scan demonstrated FDG avid lesions in the right parotid gland, cervical lymph nodes and other distant sites. Cytology report showed features of metastatic PTC. Patient underwent extended total parotidectomy with facial nerve resection, skin and masseter muscle resection and extended radical neck dissection. Final histopathology (HPE) report showed metastatic papillary carcinoma thyroid. Patient is currently on oral chemotherapy and on regular follow up. PTC rarely metastasizes to parotid gland and such cases have to be treated with surgery alone or with a combination of surgery and RAI based on tumour burden. [ABSTRACT FROM AUTHOR]

Purpose: In current image guided pretreatment patient position adjustment methods, image registration is used to determine alignment parameters. Since most positioning hardware lacks the full six degrees of freedom (DOF), accuracy is compromised. The authors show that such compromises are often unnecessary when one models the planned treatment beams as part of the adjustment calculation process. The authors present a flexible algorithm for determining optimal realizable adjustments for both step-and-shoot and arc delivery methods. Methods: The beam shape model is based on the polygonal intersection of each beam segment with the plane in pretreatment image volume that passes through machine isocenter perpendicular to the central axis of the beam. Under a virtual six-DOF correction, ideal positions of these polygon vertices are computed. The proposed method determines the couch, gantry, and collimator adjustments that minimize the total mismatch of all vertices over all segments with respect to their ideal positions. Using this geometric error metric as a function of the number of available DOF, the user may select the most desirable correction regime. Results: For a simulated treatment plan consisting of three equally weighted coplanar fixed beams, the authors achieve a 7% residual geometric error (with respect to the ideal correction, considered 0% error) by applying gantry rotation as well as translation and isocentric rotation of the couch. For a clinical head-and-neck intensity modulated radiotherapy plan with seven beams and five segments per beam, the corresponding error is 6%. Correction involving only couch translation (typical clinical practice) leads to a much larger 18% mismatch. Clinically significant consequences of more accurate adjustment are apparent in the dose volume histograms of target and critical structures. Conclusions: The algorithm achieves improvements in delivery accuracy using standard delivery hardware without significantly increasing total treatment session duration. It encourages parsimonious utilization of all available DOF. Finally, in certain cases, it obviates the need of a robotic couch having six DOF for the correction of patient displacement and rotations. [ABSTRACT FROM AUTHOR]

The immunomodulatory effect of Withania somnifera (WS) extract was tested in healthy adults. In this randomized placebo-controlled double-blinded study, subjects were allocated either 60 mg WS extract or placebo. It consists of a blinded 30-day period and an open-label extension study of another 30 days with crossover of only placebo to test. After the 30-day blinded study period, the WS test group reported significant increase (p < 0.05) in Ig's (IgA, IgM, IgG, IgG2, IgG3 and IgG4), Cytokines (IFN-γ, IL4), TBNK (CD45+, CD3+, CD4+, CD8+, CD19+, NK cells) whereas in the placebo group TBNK cells showed significant decrease (p < 0.05) and Ig's and cytokines showed no change (p > 0.05). In the extension period on day 60, the subjects on placebo who were crossed over to the WS test group showed significant increase (p < 0.05) in Ig's, cytokines and TBNK cells and the subjects who continued on the WS group showed a further significant improvement (p < 0.05) in Ig's, cytokines and TBNK cells. There were no adverse events reported in the study. WS extract significantly improved the immune profile of healthy subjects by modulating the innate and adaptive immune systems. Boosting the immune system of people at risk of infection and during widespread infections can be targeted with WS extract. [ABSTRACT FROM AUTHOR]

SHUKLA, H.H., et al.: Clinical and Quality of Life Comparison of Accelerometer, Piezoelectric Crystal, and Blended Sensors in DDDR-Paced Patients with Sinus Node Dysfunction in the Mode Selection Trial (MOST). Introduction: Permanent pacemakers are capable of increasing heart rate in response to physical activity by a variety of sensors including accelerometers, piezoelectric crystals, or blended sensors. The impact of these different physiologic sensors on cardiovascular events and quality of life is not known. Methods: Of 2,010 patients randomized in the Mode Selection Trial, 1,245 patients were selected with the most commonly used pacemakers with these three sensors. Clinical characteristics and quality of life were compared between groups at baseline, 3 months, and then yearly. Results: There were 449 patients with an accelerometer sensor device, 682 with a piezoelectric sensor, and 114 with a blended sensor. The groups were similar in terms of age (mean 74 years), gender, and cardiac risk factors but differences existed in weight, heart rate, mitral regurgitation, revascularization history, and drug therapy. The median ventricular pacing frequency was 80% (25th, 75th percentiles 42, 97). After a median follow-up of 33.1 months, the risk of death, heart failure hospitalization, atrial fibrillation, and the combined endpoint of mortality and stroke was not significantly different between the sensor types, after adjustment for baseline differences. Quality of life analyses demonstrated that patients with blended sensors had significantly worse (P < 0.01) physical function than did patients with the other two sensor systems. Moreover, patients receiving blended sensors had the poorest absolute scores, without reaching statistical significance, on 9 of 13 quality of life measures after adjusting for differences in the groups. Conclusion: We found no significant differences among the three most utilized sensors in clinical endpoints. Those patients who received blended sensors had worse physical function quality of life scores. However, clinical selection of the most sophisticated sensor for the most ill patients cannot be excluded as an explanation of these results. (PACE 2005; 28:762–770) [ABSTRACT FROM AUTHOR]

Presents information on a study which identified the clinical characteristics that distinguish patients with high defibrillation thresholds (DFT). Description of DFT testing; Methodology of the study; Results and discussion.

Venous malformations are low flow endothelial malformations with aberrant and ectatic venous channels. They are defects in vascular growth which causes functional and cosmetic impairment. Gradual growth in size of the lesion occurs due to venous congestion or thrombosis. Venous malformations in parapharyngeal space are a rare entity and are difficult to diagnose. Case Report. 13 year old boy presented with a history of hyposmia and progressive difficulty in breathing for a duration of 2.5 years. MRI face and neck with contrast showed a 4.5 × 4.3x3.6 cm lesion in the left parapharyngeal space. CT angiogram of brain and neck demonstrated a heterogeneously enhancing mass in the left parapharyngeal region. PET scan illustrated an ill-defined mass in the left pre styloid parapharyngeal space. Biopsy from the lesion showed features consistent with venolymphatic malformation. Flexible laryngoscopy showed a bulge over the left soft palate region with narrowing of nasopharyngeal lumen. Patient underwent transoral robotic surgery for complete excision of the mass. Post-operative period was uneventful. He has been on follow up for the past 1 year with no evidence of any residual or recurrent disease. Venolymphatic malformation is a rare lesion in the parapharyngeal space which is difficult to diagnose pre operatively. Surgical excision is the preferred modality of treatment for deep seated lesions in the parapharyngeal space. The advent of transoral robotic surgery have reduced the morbidity and improved clearance for such cases. [ABSTRACT FROM AUTHOR]

Introduction: Chondrosarcomas are rare malignancies of the cartilage and myxoid chondrosarcoma is its variant which commonly occurs in soft tissue of extremities. Extraskeletal chondrosarcoma is a rare malignant neoplasm of bone or soft tissue origin and is characterized by the presence of spindle cells admixed with well differentiated cartilage or chondroid stroma. They are mostly radioresistant tumours and surgical resections with adequate margins is considered as the ideal treatment modality with adjuvant radiotherapy in high grade tumours and add on chemotherapy, in case of presence of poor prognostic factors. Case Report: A 51-year-old diabetic, hypertensive female patient presented to our outpatient department with difficulty in chewing food for a duration of 6 months. On clinical examination, she had an ulceroproliferative growth involving right lower alveolus and floor of mouth. MRI face and neck with contrast showed a 4.1 × 2.9 × 4.5 cm lesion involving right lower alveolus extending to floor of mouth. Biopsy showed features of extraskeletal myxoid chondrosarcoma. She was planned for upfront surgery (Right composite resection with modified radical neck dissection with free fibula flap). Patient was stable post-surgery and was discharged in stable condition. Final histopathology report was high grade myxoid chondrosarcoma. The case was presented in tumour board and the patient was planned for adjuvant radiotherapy. She has been on regular follow up for the past 2 years and shows no signs of recurrence. Conclusion: Extraskeletal myxoid chondrosarcoma of oral cavity is a rare entity and very few cases are reported. It is a malignant neoplasm which is diagnosed with the help of immunohistochemistry. Surgery is the ideal modality of treatment accompanied by adjuvant radiotherapy in cases of high-grade tumours. [ABSTRACT FROM AUTHOR]

131-I radioactive iodine (RAI) scan is an important modality in the management of differentiated thyroid cancer to detect recurrent or residual disease. Thus it is important to have knowledge about the possibility of false positive findings in these scans to avoid wrongful diagnosis and unnecessary treatment. We here by present a patient who underwent total thyroidectomy with lymph node dissection and followed by radioactive iodine therapy for papillary thyroid cancer. He had 131-I iodine avid nodular lesion in the left parotid gland which was later proven to be oncocytoma on histopathology. False positive findings on radioactive iodine scans are a possibility which should be known to surgeons as well as nuclear medicine physicians for accurate diagnosis and appropriate management. [ABSTRACT FROM AUTHOR]

Extraosseous osteosarcoma is a rare malignant soft tissue neoplasm, and extraosseous osteosarcoma of the parotid gland is very rare. It has a very aggressive course, and there are no standardized treatment guidelines. We report the case of a 20 year old male patient who presented with history of right neck swelling since 6 years for which he had undergone right parotid surgery 5 years ago. The final histopathological report indicated that the mass was a pleomorphic adenoma. One year after the first surgery, the patient experienced recurrence of swelling over the operated site, and the size of the swelling has been increasing gradually since then. He was evaluated clinically, and a large mass was noted over the upper aspect of the right upper neck, extending to the occipital and parotid regions. An MRI scan was done which showed a 12 × 10 × 8 cm lesion centred in the right parotid gland, involving paraspinal muscles, C1–C2 vertebrae and extending into the parapharyngeal space. FNAC of the lesion showed features of pleomorphic adenoma. The patient underwent a complete excision of the tumour. The patient's post-operative period was uneventful. The final histopathological report of the patient was extraosseous osteosarcoma of the parotid gland. The patient was referred for adjuvant radiotherapy. He has been on regular follow-up for the past 6 months and has shown no sign of recurrence. EOS is an extremely rare tumour of the head and neck region which often requires extensive surgical resection with or without adjuvant radiotherapy. It has a high rate of local recurrence and a very low disease free survival. Such patients should be kept on a close follow-up. [ABSTRACT FROM AUTHOR]

Schwannomas are benign nerve tumours arising from the Schwann cells. Approximately 25-45% of schwannomas occurs in the head and neck region. Majority of schwannomas in the head and neck region arise from the vagus nerve. Trigeminal schwannomas account for about 0.2% of all intracranial tumours. Trigeminal schwannomas can originate from any section of the fifth cranial nerve, from the root to the distal extracranial branches, but majority develops from the Gasserian ganglion, usually growing in the middle cranium. Most common presenting symptom is facial pain. MRI is the imaging modality of choice and CT scan usually serves as a supplementary imaging especially for skull base tumours. 47 year old male patient presented to the outpatient department with complains of swelling over the left side of palate. Contrast enhanced CT scan demonstrated a large bilobed heterogeneously enhancing soft tissue lesion in the left infratemporal fossa with widened foramen ovale and extension of lesion into the Meckel's cave, larger contiguous component extending into ramus of mandible. MRI scan showed a large lobulated mass in the left masticator space with intracranial extension. Biopsy of the lesion was suggestive of schwannoma. The patient underwent left composite resection with dural repair and free flap reconstruction. Post operatively, on day 5 he developed features of meningitis for which he was treated conservatively and later discharged in stable condition. Trigeminal schwannomas are rare tumours with very low chance of malignant transformation which commonly presents with facial pain. MRI is the imaging modality of choice. Complete surgical excision is the treatment of choice. [ABSTRACT FROM AUTHOR]

Objectives – Transoral robotic surgery (TORS) is an already well established modality of treatment for early stage oropharyngeal cancer. This case report will throw light on the role of TORS as a treatment option for oropharyngeal cancer in a salvage setting. Methods – This is a case of a 69 year old patient who was a follow up case of carcinoma base of tongue, status - post concurrent chemoradiation who presented with residual disease at the primary site. Results – TORS was used as a successful treatment modality for base of tongue carcinoma in a salvage setting. The surgical procedure included removal of the entire hyoid bone in toto along with the tumour which is not reported in literature. The procedure also helped us in achieving an R0 resection. Conclusion – TORS should be considered as an important management modality for tongue base tumours in upfront as well as salvage setting. [ABSTRACT FROM AUTHOR]

Copyright of Southern Medical Journal is the property of Lippincott Williams & Wilkins and Copyright holder's express written permission. [Extracted from the article]

Cervical lymph node metastasis is one of the most common clinical presentations of papillary thyroid carcinoma (PTC). Occult thyroid carcinoma is described as absence of primary tumour or with presence of microcarcinoma in thyroid with cervical lymph node metastasis. Frequency of occult thyroid cancer has decreased due to developments in imaging and improved accuracy of histological examinations. 38 year old male presented to us with complaints of swelling over the left side of neck for the past 2 months. Ultrasonography was suggestive of multiple suspicious enlarged nodes in left level II, III, IV and V and fine needle aspiration cytology showed features of metastatic PTC. He was planned for total thyroidectomy with central compartment clearance and bilateral functional neck dissection. Final histopathology staging was pT0N1b. Radioactive iodine (RAI) screening showed residual functioning thyroid and later therapeutic RAI was administered. He has been on regular follow up and disease free for 1 year post treatment. Occult thyroid carcinoma is a rare diagnosis with multiple treatment plans. Few hypothesis for this entity includes tumor regression, ectopic thyroid carcinoma or missed pathological findings. [ABSTRACT FROM AUTHOR]

Myofibrosarcoma is a distinct mesenchymal malignancy which commonly occurs in head and neck region. It has a high tendency for local recurrence and distant metastasis. 39-year-old male presented with epistaxis, nasal obstruction and left sided complete loss of vision. He underwent functional endoscopic sinus surgery and guided biopsy. MRI scan showed a lesion epicentred in the left maxillary sinus, superiorly extending into the orbit. He underwent Class 4b maxillectomy with neck dissection, tracheostomy and free flap reconstruction. Histopathological examination yielded final diagnosis as myofibrosarcoma of maxilla. The patient was planned for adjuvant radiotherapy and has been disease free for 3 years. [ABSTRACT FROM AUTHOR]

Antimicrobial Resistance (AMR), as warned by WHO, is a worldwide threat to the public health which may lead to more than 10 million deaths by 2050. Among various factors responsible for AMR like irrational/misuse of antibiotics, easy access as over the counter medicine, one important factor is perception of general public about antibiotics and its use. The present study was undertaken to understand the attitude and awareness of consumers towards AMR and to evaluate the demographic patterns of various contributing factors. Questionnaire based survey was used to analyze the awareness towards AMR. Three sections of the questionnaire analyzed the attitude towards antimicrobial usage, awareness about AMR and use of antibiotics in agriculture. Out of 916 participants 79.25% were found to have good attitude towards antibiotic usage. Significant difference was noted in their attitude towards antibiotic usage and completion of antibiotic course with respect to gender, place of residence, and subjects studied. Over 70.96% participants took antibiotics only after prescription by the doctor. 72.27% participants had the awareness about AMR. Male participants studying science had significant knowledge about AMR. The awareness level towards the use of antibiotics in agriculture was low among participants and it differs with age and area of residence. Participants in our study have a good awareness and attitude towards use of antibiotics and AMR, still there is difference in awareness with gender, place of residence and subjects studied. Therefore, we need multi-directional approach to augment nationwide corrective measures and public awareness against AMR. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the oncological and functional outcomes following transoral robotic surgery (TORS) in human papilloma virus negative supraglottic cancers.Study Design: A prospective observational study at a tertiary cancer care center, New Delhi, India.Materials and Methods: From February, 2013 to December, 2015, 45 patients with supraglottic lesions underwent TORS using the da Vinci® surgical system.Results: Forty-five patients underwent TORS for supraglottic laryngectomy (SGL), with all patients undergoing bilateral neck dissection. The most common site was Ary-epiglottic fold. 47.9% were cT1 and 52.1% were cT2. Average robotic set-up time was 8.8 min and average robotic operative time was 42.9 min. A positive or close margin was seen in 12 patients (26.7%) on frozen, which were revised intraoperatively. On final histology, 3 (6.7%) patients had a margin of <5 mm. The average closest margin was 5.7 mm. Patients tolerated oral feeds within 2 weeks of procedure. All patients were HPV negative. Postoperatively, all patients had adequate swallowing and speech. Follow-up ranged from 24 to 58 months. Thirty-eight (84.4%) patients were alive and disease free.Conclusion: TORS is a safe, feasible, minimally invasive, and oncologically safe procedure in patients with early HPV supraglottic cancers. It has less morbidity and offers benefits in terms of early airway and feeding rehabilitation and avoids complications resulting from radiation therapy for these patients. [ABSTRACT FROM AUTHOR]

Context: Small cell cancer of the urinary bladder. Aims: Small cell carcinoma of the bladder is a rare histological subtype, which is particularly aggressive and global literature available describing this entity is sparse. This review of our database was to evaluate clinicopathological and survival outcomes of these patients. Subjects and Methods: The present study was a retrospective analysis of patients with small cell bladder cancer for past 6 years at Rajiv Gandhi Cancer Institute and Research Center, New Delhi. Results: Most of the patients in our study presented with limited stage disease. The overall survival and disease-free survival (DFS) was 49% and 51.07% at 2 years, respectively. Preoperative chemotherapy with surgical resection has shown significant survival and DFS benefit. Stage at presentation also affected the survival and DFS though it did not reach statistical significance. Conclusions: Small cell bladder cancer is a rare disease with dismal prognosis. Multimodality treatment with neoadjuvant chemotherapy should be the preferred treatment for limited stage disease. [ABSTRACT FROM AUTHOR]

Objective: This prospective study aimed to see long-term oncological outcome of Transoral Robotic Surgery as single modality treatment for cT1-T2 N0 HPV negative oropharyngeal malignancies.Method: From March 2013 to October 2015, 57 patients with early stage oropharyngeal carcinoma underwent Transoral robotic surgery (TORS) with neck dissection using daVinci® Surgical system. Patients were evaluated for disease free survival, overall survival, locoregional and distant metastasis.Results: 57 patients (48 males and 9 females) underwent TORS for early stage oropharyngeal carcinoma. All patients underwent ipsilateral neck dissection and 12 patients underwent bilateral neck dissection. 49 patients with final histopathology suggestive of stage I and II disease did not received any adjuvant treatment. Mean age at presentation was 59.4years (37-88years). Most common site of involvement was the base of tongue (BOT) in 31 (54.8%) patients. Twenty-four (42.1%) patients were cT1 and 33 (57.9%) were cT2 at presentation. During follow-up, 2 (4.2%) patients recurred locoreginally and 1 (2.1%) patient had distant metastasis. Two patients expired due to causes other than malignancy. Forty-three (89.6%) patients were disease free on an average follow-up of 29months with an overall survival of 93.8% at mean follow-up of 29months.Conclusion: Transoral Robotic Surgery as a single modality treatment is a good option for cure in HPV negative early resectable oropharyngeal malignancies which are relatively unresponsive to radiation. TORS can be used to de-intensify the treatment of early stage oropharyngeal carcinoma and thus avoid the early and late toxicities associated with Radiotherapy/Chemoradiotherapy. [ABSTRACT FROM AUTHOR]

Objective: The aim of this research was to assess the perioperative outcomes of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for ovarian cancers and evaluate the factors having impacts on morbidity and mortality. Design: This was a prospective, single-institutional study. Materials and Methods: The study included all patients undergoing CRS and HIPEC from November 1, 2014 to December 31, 2015, at the Rajiv Gandhi Cancer Institute and Research Centre, in New Delhi, India. Patient characteristics, disease factors, and operative outcomes were analyzed using descriptive statistics, and the impact of these variables on perioperative outcomes was evaluated using a Chi-square test. Results: Twenty-five patients, with mean age, body mass index, and body surface area of 48.7 years, 24.8kg/m2, and 1.592 m2, respectively, underwent primary (32%) or secondary (68%) CRS with HIPEC at a mean temperature of 42.5°C for 90 minutes. On average, time to oral feeds, intensive-care unit stay, and hospital stay were 3.96, 5.04, and 7.96 days, respectively. Major morbidity (Common Toxicity Criteria for Adverse Events grades 3-5) was seen in 5 patients and was significantly higher in patients aged >50 years ( p = 0.040) or with other comorbidities ( p = 0.044). Minor complications, including all chemotherapy-related complications, were seen in 36% patients with a slightly higher risk in suboptimally debulked patients. Two patients succumbed to disease in the perioperative period and were seen to have significantly longer surgeries ( p = 0.045). No other parameters were seen to affect the perioperative outcomes. Conclusions: CRS with HIPEC is feasible and safe for advanced and recurrent ovarian cancer. Patient's age, comorbidity, and surgery duration affect perioperative outcomes and may be used to define selection criteria for HIPEC. (J GYNECOL SURG 33:4) [ABSTRACT FROM AUTHOR]

Purpose: A novel rotational IMRT (rIMRT) technique using burst delivery (continuous gantry rotation with beam off during MLC repositioning) is investigated. The authors evaluate the plan quality and delivery efficiency and accuracy of this dynamic technique with a conventional flat 6 MV photon beam. Methods: Burst-delivery rIMRT was implemented in a planning system and delivered with a 160-MLC linac. Ten rIMRT plans were generated for five anonymized patient cases encompassing head and neck, brain, prostate, and prone breast. All plans were analyzed retrospectively and not used for treatment. Among the varied plan parameters were the number of optimization points, number of arcs, gantry speed, and gantry angle range (alpha) over which the beam is turned on at each optimization point. Combined rotational/step-and-shoot rIMRT plans were also created by superimposing multiple-segment static fields at several optimization points. The rIMRT trial plans were compared with each other and with plans generated using helical tomotherapy and VMAT. Burst-mode rotational IMRT plans were delivered and verified using a diode array, ionization chambers, thermoluminescent dosimeters, and film. Results: Burst-mode rIMRT can achieve plan quality comparable to helical tomotherapy, while the former may lead to slightly better OAR sparing for certain cases and the latter generally achieves slightly lower hot spots. Few instances were found in which increasing the number of optimization points above 36, or superimposing step-and-shoot IMRT segments, led to statistically significant improvements in OAR sparing. Using an additional rIMRT partial arc yielded substantial OAR dose improvements for the brain case. Measured doses from the rIMRT plan delivery were within 4% of the plan calculation in low dose gradient regions. Delivery time range was 228-375 s for single-arc rIMRT 200-cGy prescription with a 300 MU/min dose rate, comparable to tomotherapy and VMAT. Conclusions: Rotational IMRT with burst delivery, whether combined with static fields or not, yields clinically acceptable and deliverable treatment plans. [ABSTRACT FROM AUTHOR]

The accurate delivery of external beam radiation therapy is often facilitated through the implantation of radio-opaque fiducial markers (gold seeds). Before the delivery of each treatment fraction, seed positions can be determined via low dose volumetric imaging. By registering these seed locations with the corresponding locations in the previously acquired treatment planning computed tomographic (CT) scan, it is possible to adjust the patient position so that seed displacement is accommodated. The authors present an unsupervised automatic algorithm that identifies seeds in both planning and pretreatment images and subsequently determines a rigid geometric transformation between the two sets. The algorithm is applied to the imaging series of ten prostate cancer patients. Each test series is comprised of a single multislice planning CT and multiple megavoltage conebeam (MVCB) images. Each MVCB dataset is obtained immediately prior to a subsequent treatment session. Seed locations were determined to within 1 mm with an accuracy of 97±6.1% for datasets obtained by application of a mean imaging dose of 3.5 cGy per study. False positives occurred in three separate instances, but only when datasets were obtained at imaging doses too low to enable fiducial resolution by a human operator, or when the prostate gland had undergone large displacement or significant deformation. The registration procedure requires under nine seconds of computation time on a typical contemporary computer workstation. [ABSTRACT FROM AUTHOR]

Abstract: Siemens Medical Solutions, Oncology Care Systems Group (SMSOCSG) is supporting the development of several technologies that enable image acquisition and decision making processes required for IGRT in various clinical settings. Four such technologies are presented including: (i) the integration of a traditional multi-slice computed tomography (CT) scanner “on rails” with a C-arm gantry linear accelerator; (ii) the development of a high sensitivity, fast, megavoltage (MV) electronic portal imaging device capable of clinical MV Conebeam CT (MVCBCT) reconstruction and fluoroscopy mounted on a C-arm gantry linear accelerator; (iii) the modification of a mobile C-arm with flat panel kilovoltage (kV) diagnostic imager; and (iv) the development of an in-line megavoltage and kilovoltage flat panel imaging system that has the potential to image both anatomical and dosimetric information in “real-time” utilizing the traditional C-arm gantry linear accelerator geometry. Each method of IGRT has unique as well as complementary qualities which are discussed from both a clinical and technical perspective. [Copyright &y& Elsevier]