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New Results in Common Functional State Estimation for Two Linear Systems with Unknown Inputs
Jiunn Yea Ng,Chee Pin Tan,Kok Yew Ng,Hieu Trinh 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.6
This paper presents new developments in common functional observers for two systems. We improve an existing common functional observer scheme by reducing its order, and then investigate its existence conditions in terms of the original system matrices. These conditions have never been explored and they enable the users to know at the outset the class of systems for which the scheme is applicable. They also show that both observers can be designed independently of each other which significantly simplifies the design process. A numerical simulation verifies the findings.
Chee Pin Tan,Kok Yew Ng,Zhihong Man,Rini Akmeliawati 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.3
This paper presents a disturbance decoupled fault reconstruction (DDFR) scheme using two sliding mode observers in cascade. Measurable signals from the first observer are found to be the output of a fictitious system that is driven by the fault and disturbances. Then the signals are fed into a second observer which will reconstruct the fault. Sufficient conditions which guarantee DDFR are investigated and presented in terms of the original system matrices, and they are found to be less conservative than if only one single observer is used; therefore DDFR can be achieved for a wider class of systems using two sliding mode observers. A simulation example validates the claims made in this paper.
A Review on 3D Printed Bioimplants
Chee Meng Benjamin Ho,Sum Huan Ng,윤용진 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
Additive manufacturing (AM) also known as 3D printing have been making inroads into medical applications such as surgical models and tools, tooling equipment, medical devices. One key area researchers are looking into is bioimplants. With the improvement and development of AM technologies, many different bioimplants can be made using 3D printing. Different biomaterials and various AM technologies can be used to create customized bioimplants to suit the individual needs. With the aid of 3D printing this could lead to new foam and design of bioimplants in the near further. Therefore, the purpose of this review articles is to (1) Describe the various AM technologies and process used to make bioimplants, (2) Different types of bioimplants printed with AM and (3) Discuss some of the challenges and future developments for 3D printed bioimplants.
Heart failure as the first manifestation of renal cell carcinoma
Chee Meng Lee,Allen Sim,Gunasegaran Kurugulasigamoney,Lay Guat Ng 대한비뇨의학회 2015 Investigative and Clinical Urology Vol.56 No.1
We report the rare case of a patient with advanced renal cell carcinoma (RCC) who initially presented to the hospital with symptoms of cardiac failure. Preoperative cardiac studies did not reveal any underlying ischemia. After resection of a large 14-cm left renal tumor, cardiac function was noted to improve dramatically. We discuss this case of concomitant RCC and nonischemic cardiomyopathy.
Phua, Chee Ee,Ung, Ngie Min,Tan, Boon Seang,Tan, Ai Lian,Eng, Kae Yann,Ng, Bong Seng Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12
Purpose: To study the effect of bolus versus no bolus in the coverage of the nodal tumour volume with intensity-modulated radiotherapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC). Methods and Materials: This retrospective study used data from 5 consecutive patients with NPC who were treated with bolus for large neck nodes using IMRT from November 2011-January 2012 in our institute. All these patients were treated radically with IMRT according to our institution's protocol. Re-planning with IMRT without bolus for these patients with exactly the same target volumes were done for comparison. Comparison of the plans was done by comparing the V70 of PTV70-N, V66.5 of PTV70-N, V65.1 of PTV70-N and the surface dose of the PTV70-N. Results: The mean size of the largest diameter of the enlarged lymph nodes for the 5 patients was 3.9 cm. The mean distance of the GTV-N to the skin surface was 0.6 cm. The mean V70 of PTV70-N for the 5 patients showed an absolute advantage of 10.8% (92.4% vs. 81.6%) for the plan with bolus while the V66.5 of PTV70-N had an advantage of 8.1% (97.0% vs. 88.9%). The mean V65.1 also had an advantage of 7.1% (97.6% vs. 90.5%). The mean surface dose for the PTV70-N was also much higher at 61.1 Gy for the plans with bolus compared to only 23.5 Gy for the plans without bolus. Conclusion: Neck node bolus technique should be strongly considered in the treatment of NPC with enlarged lymph nodes treated with IMRT. It yields a superior dosimetry compared t o non-bolus plans with acceptable skin toxicity.
Intensity-Modulated Radiotherapy for Nasopharyngeal Carcinoma: Penang General Hospital Experience
Phua, Chee Ee,Tan, Boon Seang,Tan, Ai Lian,Eng, Kae Yann,Ng, Bong Seng,Malik, Rozita Abdul,Ishak, Wan Zamaniah Wan Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.7
Purpose: To study the overall treatment time (OTT) and acute toxicity of intensity-modulated radiotherapy (IMRT) treatment for nasopharyngeal carcinoma (NPC). Methods: This retrospective study covered all NPC patients who underwent radical IMRT treatment at the Penang General Hospital from June 2011 to February 2012. Patients of any age and stage of disease with histologically proven diagnosis were included. Information was collected on patient demographics, clinical stage, treatment received, including any neoadjuvant and/or concurrent chemotherapy, acute toxity and completion of IMRT within the OTT. Results: A total of 26 NPC patients were treated with IMRT during the study period; 88.5% had stage III/IV disease. 45.2% received neo-adjuvant chemotherapy while 50.0% were given concurrent chemo-irradiation. All patients completed the treatment and 92.3% within the 7 weeks OTT. Xerostomia was present in all patients with 92.3% having grade 2. Severe grade III/IV acute toxicity occurred in 73.1% of patients, the commonest of which was oral mucositis (57.6%). This was followed by dysphagia which occurred in 53.8%, skin reactions in 42.3% and weight loss in 19.2%. However, haematological toxicity was mild with only one patient having leucopaenia. Conclusion: IMRT treatment for NPC is feasible in our center. More importantly, it can be delivered within the 7 weeks OTT in the majority of patients. Severe grade 3/4 toxicity is very common (73.1%) and thus maximal nutritional and analgesic support is required throughout the treatment.
Phua, Chee Ee,Bustam, Anita Zarina,Yusof, Mastura Md.,Saad, Marniza,Yip, Cheng-Har,Taib, Nor Aishah,Ng, Char Hong,Teh, Yew Ching Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9
Background: The risk of treatment-related death (TRD) and febrile neutropaenia (FN) with adjuvant taxane-based chemotherapy for early breast cancer is unknown in Malaysia despite its widespread usage in recent years. This study aims to determine these rates in patients treated in University Malaya Medical Centre (UMMC). Patients and Methods: Patients who were treated with adjuvant taxane-based chemotherapy for early breast cancer stages I, II or III from 2007-2011 in UMMC were identified from our UMMC Breast Cancer Registry. The TRD and FN rates were then determined retrospectively from medical records. TRD was defined as death occurring during or within 30 days of completing chemotherapy as a consequence of the chemotherapy treatment. FN was defined as an oral temperature > $38.5^{\circ}C$ or two consecutive readings of > $38.0^{\circ}C$ for 2 hours and an absolute neutrophil count < $0.5{\times}10^9/L$, or expected to fall below $0.5{\times}10^9/L$. Results: A total of 622 patients received adjuvant chemotherapy during this period. Of these patients 209 (33.6%) received taxane-based chemotherapy. 4 taxane-based regimens were used namely the FEC-D, TC, TAC and AC-PCX regimens. The commonest regimen employed was the FEC-D regimen accounting for 79.9% of the patients. The FN rate was 10% and there was no TRD. Conclusion: Adjuvant taxane-based chemotherapy in UMMC for early breast cancer has a FN rate of 10%. Primary prophylactic G-CSF should be considered for patients with any additional risk factor for FN.
Vincent Phua, Chee Ee,Tan, Boon Seang,Tan, Ai Lian,Eng, Kae Yann,Ng, Bong Seng,Ung, Ngie Min Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.4
Background: To compare the dosimetric coverage of target volumes and organs at risk in the radical treatment of nasopharyngeal carcinoma (NPC) between intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT). Materials and Methods: Data from 10 consecutive patients treated with IMRT from June-October 2011 in Penang General Hospital were collected retrospectively for analysis. For each patient, dose volume histograms were generated for both the IMRT and 3DCRT plans using a total dose of 70Gy. Comparison of the plans was accomplished by comparing the target volume coverage (5 measures) and sparing of organs at risk (17 organs) for each patient using both IMRT and 3DCRT. The means of each comparison target volume coverage measures and organs at risk measures were obtained and tested for statistical significance using the paired Student t-test. Results: All 5 measures for target volume coverage showed marked dosimetric superiority of IMRT over 3DCRT. V70 and V66.5 for PTV70 showed an absolute improvement of 39.3% and 24.1% respectively. V59.4 and V56.4 for PTV59.4 showed advantages of 18.4% and 16.4%. Moreover, the mean PTV70 dose revealed a 5.1 Gy higher dose with IMRT. Only 4 out of 17 organs at risk showed statistically significant difference in their means which were clinically meaningful between the IMRT and 3DCRT techniques. IMRT was superior in sparing the spinal cord (less 5.8Gy), V30 of right parotid (less 14.3%) and V30 of the left parotid (less 13.1%). The V55 of the left cochlea was lower with 3DCRT (less 44.3%). Conclusions: IMRT is superior to 3DCRT due to its dosimetric advantage in target volume coverage while delivering acceptable doses to organs at risk. A total dose of 70Gy with IMRT should be considered as a standard of care for radical treatment of NPC.