ABSTRACT
Objective: Chemoradiation therapy is among the standard treatments for cancer, which often causes a decrease in appetite and subsequent weight loss. When weight loss occurs during treatment, the external body contour changes from that indicated during initial planning, causing changes in dose distribution to the target tumor regions and organs at risk (OARs). This study aimed to examine the dose changes to both the target regions and OARs, based on the dose-volume histogram (DVH).Methods: We established a 60 mm-diameter planning target volume (PTV) and a 30 mm-diameter rectum region of interest (OAR), using a phantom; this was followed by a 50 Gy/25 fraction irradiation to the target region that was measured using a two-dimensional-array ion chamber device. The measurement was conducted by varying the bolus thickness from 0 to −25 mm, in 5 mm decrements. In addition, the maximum dose for both PTV and OAR were evaluated based on the DVH, created using the Adaptive software.Results: The gamma analysis showed that the pass rate was less than 95% when the bolus thickness was altered by −25 mm for the helical delivery mode and by −10 mm for the direct delivery mode, resulting in a dose error greater than 3%. Results of the DVH evaluation revealed that the maximum dose of PTV increased by 5.18% when the bolus thickness was −25 mm for helical delivery, whereas a 9.95% increase was noted for the direct delivery mode compared with the dose at the reference level of 0 mm bolus thickness.Discussion: Our results suggest that it is necessary to formulate a new treatment plan owing to increased dose error, if the body thickness decreases by more than 20 mm and 10 mm for the helical and direct delivery modes, respectively. The results also demonstrate that helical delivery is less affected by changes in body thickness than direct delivery.
ABSTRACT
Aim: In order to integrate malaria Intermittent Preventive Treatment in infants (IPTi) into the Ghana national immunization programme, there was the need to evaluate the feasibility of IPTi by assessing the intervention operational issues including its implementation costs, and its cost effectiveness. Study Design: Cross-sectional study. Place and Duration of Study: Upper East Region, Ghana, between July 2007 and July 2009 Methods: We calculated the costs of administrating IPTi during vaccination sessions; the costs of programme implementation during the first year of implementation (start-up costs) and in routine years (recurrent costs). For the purposes of cost-effectiveness analysis, all economic costs (including financial and opportunity costs) and the net cost were estimated. To estimate the cost effectiveness ratios of IPTi, the aggregate cost of providing the intervention for a reference target population of 1,000 infants was divided by its health outcome. Sensitivity analyses were carried out to understand the results robustness. Results: IPTi gross costs in start up and in routine years were estimated at 70.66 cents and 29.72 cents per dose, or $2.0 and $0.87 per infant, respectively. The gross cost per DALY saved was estimated at $3.49 and the net cost of IPTi for 1,000 infants was $-3,416.38 in the routine years rending IPTi a highly cost saving intervention. Sensitivity analyses showed that the cost per DALY saved never went up more than $4.50 maintaining the intervention still highly cost effective. Conclusion: IPTi in Ghana is a highly and robust cost effective intervention. The intervention is cost-saving and should be scaled up nationally to save children’s health and economic capital.