SU-E-T-636: Comparison of RapidArc-Based Radiosurgery with Cone-Based Cyberknife Treatment for Multiple Intracranial Tumors

PURPOSE

To investigate the feasibility of RapidArc technique on intracranial radiosurgery for multiple lesions.

METHODS

Six patients who were previously treated using cone-based technique, Cyberknife were included in this study. These patients have multiple lesions (6-9, mostly metastasis). In our current clinical practice, each lesion was planned and treated individually. The prescription was 15-21 Gy at 80% with single fraction. These cases were replanned with RapidArc on the platform of Varian Truebeam STx equipped with high resolution MLC leaves of 2.5mm at center. The maximum dose rate is 1400 MU/min at 6 MV for flattering filter free mode. Because of long span of multiple lesions, the targets were divided into two groups with two isocenters. Each plan with one isocenter contains 4 non-coplanar arcs, and dose optimization was performed with the two plans combined. Critical organs, such as eyes, brainstem and brain were constrained. The individual Cyberknife plans were summed to compare with the RapidArc plan. Scenarios of setup error were simulated during RapidArc treatment.

RESULTS

RapidArc plans can achieve comparable target coverage and normal tissue avoidance to Cyberknife plans. The brain dose volume histogram (DVH) curves of the two techniques are similar in spite of different appearance of their 3D dose distributions. MU is much higher for summed Cyberknife plan. Because RapidArc can treat several lesions together, the complete treatment time for all lesions is significantly reduced. However RapidArc treatment is susceptible to setup error, which may cause increase in normal tissue dose and decrease in target dose coverage. The level of discrepancy depends on the magnitude of setup error, location and dose distribution of the target.

CONCLUSION

Multiple brain lesions treatment with RapidArc radiosurgery is clinically feasible with setup error fully accounted. It can provide dose performance comparable to cone-based Cyberknife treatment.

SU-E-T-220: A Web-Based Research System for Outcome Analysis of NSCLC Treated with SABR

PURPOSE

To establish a web-based software system, an electronic patient record (ePR), to consolidate and evaluate clinical data, dose delivery and treatment outcomes for non small cell lung cancer (NSCLC) patients treated with hypofractionated stereotactic ablative radiation therapy (SABR) across institutions.

METHODS

The new trend of information technology in medical imaging and informatics is towards the development of an electronic patient record (ePR), in which all health and medical information of each patient are organized under the patient's name and identification number. The system has been developed using the Wamp Server, a package of Apache web server, PHP and MySQL database to facilitate patient data input and management, and evaluation of patient clinical data and dose delivery across institution using web technology. The data of each patient to be recorded in the database include pre-treatment clinical data, treatment plan in DICOM-RT format and follow-up data. The pre-treatment data include demographics data, pathology condition, cancer staging. The follow-up data include the survival status, local tumor control condition and toxicity. The clinical data are entered to the system through the web page while the treatment plan data will be imported from the treatment planning system (TPS) using DICOM communication.

RESULTS

The collection of data of NSCLC patients treated with SABR stored in the ePR is always accessible and can be retrieved and processed in the future. The core of the ePR is the database which integrates all patient data in one location.

CONCLUSIONS

The web-based DICOM RT ePR system utilizes the current state-of-the-art medical informatics approach to investigate the combination and consolidation of patient data and outcome results. This will allow clinically-driven data mining for dose distributions and resulting treatment outcome in connection with biological modeling of the treatment parameters to quantify the efficacy of SABR in treating NSCLC patients.

Emergence of multidrug-resistant NDM-1-producing Gram-negative bacteria in Bangladesh

The main objective of this study was to investigate the prevalence of bla (NDM-1) in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the bla (NDM-1) gene. Among 403 isolates, 14 (3.5 %) were positive for bla (NDM-1), and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla (NDM-1)-positive isolates were resistant to multiple antibiotics. Among β-lactamase genes, bla (CTX-M-1-group) was detected in ten isolates (eight bla (CTX-M-15)), bla (OXA-1-group) in six, bla (TEM) in nine, bla (SHV) in seven, and bla (VIM) and bla (CMY) in two isolates each. The 16S rRNA methylase gene, armA, was detected in five K. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and two K. pneumoniae isolates, respectively. qnr genes were detected in two K. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60-100 MDa) carrying bla (NDM-1) were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5 % of Gram-negative clinical isolates in Bangladesh are NDM-1-producing.

A pilot study on the prevalence of sexually transmitted infections among clients of brothel-based female sex workers in Jessore, Bangladesh

The prevalence of bacterial sexually transmitted infections among clients of female sex workers (FSWs) was studied. A total of 156 condoms were collected from clients of 13 sex workers during three consecutive days. Condoms used by clients of FSWs were collected and DNA was extracted from the seminal fluid and used for the diagnosis of Neisseria gonorrhoeae, Chlamydia trachomatis and Trichomonas vaginalis by polymerase chain reaction. The prevalence of N. gonorrhoeae, C. trachomatis and T. vaginalis among clients of FSWs was 4.5% (7/156), 2.5% (4/156) and 7% (11/156), respectively.