Evaluation of imaging performance of major image guidance systems

Purpose: The imaging characteristics of two popular kV cone-beam CT (CBCT) and two MVCT systems utilised in image-guided radiation therapy (IGRT) were evaluated. Materials and methods: The study was performed on Varian Clinac iX, Elekta Synergy S, Siemens Oncor, and Tomotherapy. A CT phantom (Catphan-504, Phantom Laboratory, Salem, NY) was scanned for measurements of image quality including image noise, uniformity, density accuracy, spatial resolution, contrast linearity, and contrast resolution. The measurement results were analysed using in-house image analysis software. Reproducibility, position correction, and geometric accuracy were also evaluated with markers in a smaller alignment phantom. The performance evaluation compared volumetric image properties from these four systems with those from a conventional diagnostic CT (CCT). Results: It was shown that the linearity of the two kV CBCT was fairly consistent with CCT. The Elekta CBCT with half-circle 27-cm FOV had higher CT numbers than the other three systems. The image noises of the Elekta kV CBCT, Siemens MV CBCT, and Tomotherapy fan-beam CT (FBCT) are about 2-4 times higher than that of the Varian CBCT. The spatial resolutions of two kV CBCTs and two MV CBCTs were 8-11 lp/cm and 3-5 lp/cm, respectively. Conclusion: Elekta CBCT provided a faster image reconstruction and low dose per scan for half-circle scanning. Varian CBCT had relatively lower image noise. Tomotherapy FBCT had the best uniformity.

17-year follow-up of a randomized prospective controlled trial of adjuvant intravesical doxorubicin in the treatment of superficial bladder cancer

PURPOSE: To evaluate the efficacy of adjuvant intravesical doxorubicin in superficial transitional cell carcinoma of the urinary bladder on long-term follow-up. MATERIALS AND METHODS: Between July 1986 and November 1991, all patients harboring superficial bladder cancers (Ta or T1) with one or more of these criteria (stage > a, grade > 1, size > 1 cm, multiple or recurrent tumors) were randomized to receive either 50 mg doxorubicin or no adjuvant therapy. Patients with recurrences were allowed to receive doxorubicin or other intravesical agents. Recurrence, progression and survival were analyzed. RESULTS: There were 82 patients included (64 males and 18 females). The mean age was 64 years. Forty-six patients were randomized to the doxorubicin group and 36 to the control group. Final analysis was made at median follow-up of 45, 128 and 131.5 months for recurrence, progression and survival, respectively. Recurrence free, progression free and disease specific survival did not differ significantly between groups. The 10-year Kaplan-Meier estimates for recurrence free, progression free and disease specific survival were 67 percent, 84 percent and 92 percent, respectively for the doxorubicin group, and were 50 percent, 89 percent and 97 percent, respectively for the control group. Tumor size predicted recurrence (p = 0.013) and grade predicted progression (p = 0.004) with multivariate analysis. CONCLUSIONS: Adjuvant intravesical doxorubicin could not be shown to improve recurrence, progression and survival of superficial bladder cancer, compared with control on long-term follow-up. Tumor size and grade were shown to be prognostic factors for recurrence and progression, respectively.

Risk factors for hypoxemia and respiratory failure in respiratory syncytial virus bronchiolitis.

Respiratory syncytial virus (RSV) bronchiolitis is a common infection in young children and may result in hospitalization. We examined the incidence of, and risk factors associated with, hypoxemia and respiratory failure in 216 children aged < 24 months admitted consecutively for proven RSV bronchiolitis. Hypoxemia was defined as SpO2 < 90% in room air and severe RSV bronchiolitis requiring intubation and ventilation was categorized as respiratory failure. Corrected age at admission was used for premature children (gestation < 37 weeks). Hypoxemia was suffered by 31 (14.3%) children. It was more likely to occur in children who were Malay (OR 2.56, 95%CI 1.05-6.23, p=0.03) or premature (OR 6.72, 95%CI 2.69-16.78, p<0.01). Hypoxemia was also more likely to develop in children with failure to thrive (OR 2.96, 95%CI 1.28-6.82, p<0.01). The seven (3.2%) children who were both premature (OR 11.94, 95%CI 2.50-56.99, p<0.01) and failure to thrive (OR 6.41, 95%CI 1.37-29.87, p=0.02) were more likely to develop respiratory failure. Prematurity was the only significant risk factor for hypoxemia and respiratory failure by logistic regression analysis (OR 1.17, 95%CI 1.06-1.55, p<0.01 and OR 1.14 95%CI 1.02-2.07, p=0.02 respectively). Prematurity was the single most important risk factor for both hypoxemia and respiratory failure in RSV bronchiolitis.

The direct cost of treating bronchial asthma in a teaching hospital in Malaysia.

A pilot study to evaluate the direct cost of treating 51 adults and 50 children with bronchial asthma was conducted. All aspects of the medical care provided over a 6-month period were considered. The mean treatment costs per month were US dollars 22.97 (adults) and US dollars 15.56 (children). The cost of maintenance therapy accounted for 55.5% and 73.4% of the total direct cost treatment for adults and children respectively. Only 27 (52.9%) adults and 17 (34.0%) children paid for their inhaled prophylactic drugs, amounting to 12.3% of the total maintenance therapy costs. Thirteen (25.4%) adults and 9 (18.0%) children were using alternative therapy at a monthly cost of US dollars 41.50 and US dollars 16.77 respectively. A substantial proportion of the direct cost of asthma treatment is heavily subsidized in Malaysia. Adequate attention to the allocation of the health budget, to ensure the optimal provision of health care, is warranted.

Mycoplasma Pneumoniae infection in Malaysian children admitted with community acquired pneumonia.

Mycoplasma pneumoniae is increasingly recognized as an important cause of community acquired pneumonia (CAP) in children. We determined the importance of M. pneumoniae as a causative agent in 170 children aged 1 month to 15 years who were hospitalized with CAP over a 6-month period. The diagnosis of M. pneumoniae infection was based on serological evidence obtained by a particle agglutination test (SERODIA-MYCO II). A positive serological diagnosis was made if the acute phase serum titer was more than 1:160 or paired samples taken 2-4 weeks apart showed a four-fold or greater rise in the serum titer. M. pneumoniae was identified as the causative agent in 40 (23.5%) children. Children with M. pneumoniae infection were more likely to be older than 3 years (OR 4.0 95%CI 1.8-9.1, p<0.001), Chinese (OR 4.3 95%CI 2.0-8.9, p<0.001), have a duration of illness longer than 7 days prior to admission (OR 6.0 95%CI 2.7-13.5, p<0.001) and have perihilar interstitial changes on chest X-ray (OR 4.6 95%CI 2.2-9.9, p<0.001). A significant number of hospital admissions for CAP in Malaysian children can be attributed to M. pneumoniae. It is important to identify these children so as to administer the most appropriate antibiotic treatment.