تجزیه و تحلیل به حداقل رساندن هزینه تصویربرداری نیروی برق برحسب هزار ولت با بازسازی موقعیت خودکار در مقابل به حداقل رساندن هزینه تصویربرداری پورتال الکترونیکی در رادیوتراپی تصویر هدایت شده برای سرطان پروستات

Aims To compare the treatment time and cost of prostate cancer fiducial marker image-guided radiotherapy (IGRT) using orthogonal kilovoltage imaging (KVI) and automated couch shifts and orthogonal electronic portal imaging (EPI) and manual couch shifts. Materials and methods IGRT treatment delivery times were recorded automatically on either unit. Costing was calculated from real costs derived from the implementation of a new radiotherapy centre. To derive cost per minute for EPI and KVI units the total annual setting up and running costs were divided by the total annual working time. The cost per IGRT fraction was calculated by multiplying the cost per minute by the duration of treatment. A sensitivity analysis was conducted to test the robustness of our analysis. Treatment times without couch shift were compared. Results Time data were analysed for 8648 fractions, 6057 from KVI treatment and 2591 from EPI treatment from a total of 294 patients. The median time for KVI treatment was 6.0 min (interquartile range 5.1–7.4 min) and for EPI treatment it was 10.0 min (interquartile range 8.3–11.8 min) (P value < 0.0001). The cost per fraction for KVI was A$258.79 and for EPI was A$345.50. The cost saving per fraction for KVI varied between A$66.09 and A$101.64 by sensitivity analysis. In patients where no couch shift was made, the median treatment delivery time for EPI was 8.8 min and for KVI was 5.1 min. Conclusions Treatment time is less on KVI units compared with EPI units. This is probably due to automation of couch shift and faster evaluation of imaging on KVI units. Annual running costs greatly outweigh initial setting up costs and therefore the cost per fraction was less with KVI, despite higher initial costs. The selection of appropriate IGRT equipment can make IGRT practical within radiotherapy departments.

Dose escalation in prostate cancer reduces biochemical failure [1]. Image-guided radiotherapy (IGRT) may allow safe dose escalation by avoidance of inadvertent irradiation of normal tissue [2] and [3]. There are numerous methods for conducting IGRT in prostate cancer [4] and [5]. In our experience, IGRT using implanted fiducial markers and orthogonal imaging is emerging as a practical, reliable and effective method to ensure target localisation before each fraction of radiotherapy [6] and [7]. Previous studies have shown that online prostate fiducial marker IGRT with orthogonal electronic portal imaging (EPI) takes longer to deliver than conventional prostate radiotherapy [8]. For many departments, the longer treatment time with IGRT may affect waiting lists. Technology that reduces treatment time could make IGRT more practical for routine implementation in busy radiotherapy departments. Several recent linear accelerator engineering innovations may allow quicker IGRT treatment. Gold seed fiducial markers show up with more clarity on kilovoltage imaging (KVI) compared with megavoltage imaging (MVI; see Figure 1) [9], [10] and [11]. Another recently introduced technology is automated couch repositioning, which refers to the adjustment of the treatment couch made directly from the treatment console without the radiation therapist having to re-enter the treatment room [12]. A 2007 survey of UK National Health Service radiotherapy centres showed that nearly half the centres surveyed did not plan on implementing IGRT mostly due to cost issues [13]. The purpose of this study was to compare IGRT treatment time using EPI with manual shift and KVI with automated shift to determine if costs can be saved by using new technology in IGRT through any potential reduction in treatment time. The purchase costs of new technology are greater, and it is unknown if any potential reduction in treatment time could offset this. To explore this, a cost minimisation analysis was conducted, whereby we assumed that the two units have equivalent clinical outcomes and only financial costs were explored [14].

There are several reasons why treatment time reduction is preferable in radiotherapy, i.e. it is more convenient for the patient, it results in a cost saving for the department, and there is a theoretical reduction in geographical miss of the tumour due to a reduction in intrafraction motion. The finding in this study is not unexpected, as we have two new time saving technologies being assessed, and we would expect to find that KVI with automated couch shift is slightly quicker than MVI with manual couch shift. This time analysis was conducted to quantify the difference, and it was unexpected that we found that patients who did not have a couch shift at all also had a treatment time reduction by 3.62 min, which leads us to conclude that other factors in the workflow, such as interpretation of imaging, is quicker on the KVI units. Many centres still use MVI for IGRT, and manual couch shift, because of cost issues. This study supports the use of new technology in IGRT equipment, which could result in an overall cost saving through faster treatment time.