PV QA 3 - Poster Viewing Q&A 3
Purpose/Objective(s):Significant anatomic changes as well as tumour shrinkage are not uncommon in radiation treatment of NPC. Timely adaptive planning is essential to correct for the resultant dose discrepancy from the original IMRT plan. However the re-planning process is time consuming and the correction would be delayed. This study compared the efficiency of re-planning using deformable auto-segmentation (AS) and Knowledge-Based Planning (KBP) with re-planning using conventional means.
Materials/Methods:A total of 20 consecutive NPC patients who had undergone adaptive re-planning for IMRT treatment between Nov 2016 and Aug 2017 were retrospectively studied. The re-planning usually took place in the 4th week of the 7-week treatment. For the conventional planning process, the organs-at-risk (OAR) and pseudo-structures (for IMRT optimization) were produced manually. The plans were optimized using universal template of dose constraints with, if necessary, manual editing of beam fluence afterwards. The re-planning was then repeated with OARs produced by an imaging informatics system by deforming those in the initial plan, and the optimization performed with the KBP system RapidPlan (Varian Medical Systems). Target volumes were all contoured by clinicians manually in both cases. Plan optimization was only stopped when the plans were deemed clinically acceptable. Times for structure contouring and IMRT planning were recorded for both the conventional process and re-planning employing AS and KBP. Student t-test was used to compare the performance of the two processes with significance level at p = 0.05.
|Mean time (min) for:||Conventional process||Using AS and KBP|
|GTV and CTV contouring||48.5|
|Total time of re-planning||453.45||207.5|
Conclusion:Our results showed that the whole re-planning process could be speeded up by more than 2 fold with the use of AS and KBP without jeopardizing the planning quality.
The asset you are trying to access is locked. Please enter your access key to unlock.