Hippocampal-sparing whole-brain radiotherapy using Elekta equipment.

The purpose of this study was to evaluate the feasibility of hippocampal-sparing whole-brain radiotherapy (HS WBRT) using the Elekta Infinity linear accelerator and Monaco treatment planning system (TPS). Ten treatment plans were created for HS-WBRT to a dose of 30 Gy (10 fractions). RTOG 0933 recommendations were applied for treatment planning. Intensity-modulated radiotherapy (IMRT) plans for the Elekta Infinity linear accelerator were created using Monaco 3.1 TPS-based on a nine-field arrangement and step-and-shoot delivery method. Plan evaluation was performed using D2% and D98% for the whole-brain PTV (defined as whole brain excluding hippocampus avoidance region), D100% and maximum dose to the hippocampus, and maximum dose to optic nerves and chiasm. Homogeneity index (HI) defined as (D2%-D98%)/Dmedian was used to quantify dose homogeneity in the PTV. The whole-brain PTV D2% mean value was 37.28 Gy (range 36.95-37.49Gy), and D98% mean value was 25.37 Gy (range 25.40-25.89 Gy). The hippocampus D100% mean value was 8.37 Gy (range 7.48-8.97 Gy) and the hippocampus maximum dose mean value was 14.35 Gy (range 13.48-15.40 Gy). The maximum dose to optic nerves and optic chiasm for all patients did not exceed 37.50 Gy. HI mean value was 0.36 (range 0.34-0.37). Mean number of segments was 105 (range 88-122) and mean number of monitor units was 1724 (range 1622-1914). Gamma evaluation showed that all plans passed 3%, 3 mm criteria with more than 99% of the measured points. These results indicate that Elekta equipment (Elekta Infinity linac and Monaco TPS) can be used for HS WBRT planning according to compliance criteria defined by the RTOG 0933 protocol.

CT appearances of post-radiation livers in patients with unresectable cholangiocarcinoma.

OBJECTIVE: To characterize the computed tomographic (CT) findings of post-radiation livers and the interval changes in patients with unresectable cholangiocarcinoma. MATERIAL AND METHOD: Thirteen patients with unresectable cholangiocarcinoma who received concurrent chemoradiation with conformal radiotherapy technique (50 to 66 Gy, 2 Gy/fraction) were included in the present study. CT at pre-radiation and sequential follow-up at 1, 3, 6, 9 and 12 months were retrospectively reviewed by two abdominal radiologists to identify CT characteristics of post-radiation liver and the interval changes. RESULTS: CT at pre-radiation and sequential follow-up at 1, 3, 6, 9 and 12 months were available in 92.3%, 100%, 76.9%, 53.8%, 30.8% and 23.1%, respectively. Post-radiation livers showed sharply-delineated, hypodense radiation areas, which were well related with the isodose line of 35 to 56 Gy (mean = 44.4 +/- 6.55 Gy). These radiation areas were mostly appreciated on portal venous phase at 1-month follow-up study in 12 of 13 (92.3%) patients and these were gradually less defined in subsequent studies. Progressive decrease size of radiation areas with persistent enhancement on delayed phase images were recognized. Progression of hepatic cortical irregularity was seen in four (30.8%) patients, as well as pulmonary fibrosis of lung bases. CONCLUSION: Post-radiation liver in patients with unresectable cholangiocarcinoma showed a sharply-defined, hypodense radiation area, which was mostly appreciated in 1-month follow-up CT and was gradually less defined in subsequent studies with evidence of progressive atrophic change.

Economic evaluation of policy options for prevention and control of cervical cancer in Thailand.

BACKGROUND: The Thai healthcare setting has seen patients with cervical cancer experience an increasing burden of morbidity and mortality, a stagnation in the performance of cervical screening programmes and the introduction of a vaccine for the prevention of human papillomavirus (HPV) infection. OBJECTIVE: This study aims to identify the optimum mix of interventions that are cost effective, from societal and healthcare provider perspectives, for the prevention and control of cervical cancer. METHODS: A computer-based Markov model of the natural history of cervical cancer was used to simulate an age-stratified cohort of women in Thailand. The strategy comparators, including both control and prevention programmes, were (i) conventional cytology screening (Pap smears); (ii) screening by visual inspection with acetic acid (VIA); and (iii) HPV-16, -18 vaccination. Input parameters (e.g. age-specific incidence of HPV infection, progression and regression of the infection, test performance of screening methods and efficacy of vaccine) were synthesized from a systematic review and meta-analysis. Costs (year 2007 values) and outcomes were evaluated separately, and compared for each combination. The screening strategies were started from the age of 30-40 years and repeated at 5- and 10-year intervals. In addition, HPV vaccines were introduced at age 15-60 years. RESULTS: All of the screening strategies showed certain benefits due to a decreased number of women developing cervical cancer versus 'no intervention'. Moreover, the most cost-effective strategy from the societal perspective was the combination of VIA and sequential Pap smear (i.e., VIA every 5 years for women aged 30-45 years, followed by Pap smear every 5 years for women aged 50-60 years). This strategy was dominant, with a QALY gain of 0.01 and a total cost saving of Baht (Bt) 800, compared with doing nothing. From the societal perspective, universal HPV vaccination for girls aged 15 years without screening resulted in a QALY gain of 0.06 at an additional cost of Bt 8,800, based on the cost of Bt 15,000 for a full immunization schedule. The incremental cost-effectiveness ratio, comparing HPV vaccinations for girls aged 15 years with the current national policy of Pap smears for women aged 35-60 years every 5 years, was approximately Bt 18,1000 per QALY gained. This figure was relatively high for the Thai setting. CONCLUSIONS: The results suggest that controlling cervical cancer by increasing the numbers of women accepting the VIA and Pap smear screening as routine and by improving the performance of the existing screening programmes is the most cost-effective policy option in Thailand.