Feasibility Study of an Efficient Plan Pool Adaptive Radiotherapy Technology Based on Low-dose Computed Tomography...

Online adaptive radiotherapy (oART) involves a complex workflow across multiple departments, requiring significant resources and increasing the workload of radiation oncologists (ROs) and physicists. For cervical cancer, there is a need for a low-dose, image-guided adaptive radiotherapy solution that is both efficient and clinically effective AIMS: The aim is to explore the feasibility and performance of a plan-pool adaptive radiotherapy (plan-pool ART) workflow, with a focus on efficiency and dosimetric benefits for both the tumour and organs at risk (OARs).

A plan-pool ART framework was developed for cervical cancer radiotherapy based on the daily low-dose computed tomography (LDCT). The LDCT images were synthesised into high-quality restorative CT (RCT) images by an image-synthesis model. A total of 257 fractionated fan-beam computed tomography (FBCT) datasets from 17 cervical cancer patients treated with the oART regimen were collected (171 fractions treated with oART and 86 fractions treated with the original plan). A support vector machine (SVM) was used to train (180 cases) and evaluate (77 cases) the oART classification model, which predicts whether the fraction needs to execute oART. The oART classification model selects the daily treatment plan that best aligns with the patient's anatomical positions from the plan pool. Finally, the performance of image-guided radiotherapy (IGRT), plan-pool ART, and triggered oART (trigger-oART) techniques was compared by simulating treatments for 5 cervical cancer cases.

The oART classification model achieved high predictive performance, with an under the curve (AUC) of 0.98, accuracy of 0.86, recall of 0.89, and specificity of 0.92. Plan-pool ART reduced the number of oART execution (1.4 vs 3.0 for trigger-oART) while optimising dosimetry. Compared to IGRT, plan-pool ART decreased mean bladder dose (3122cGy vs 3258cGy) and rectum dose (3265cGy vs 3325cGy), along with lower V_4500cGy values for both organs. Target coverage remained comparable across techniques, but IGRT showed greater variability in CTV D_99%, leading to potential underdosing.

The simulation results demonstrate that the plan-pool ART technology is feasible, ensuring reliable target dose coverage, reducing the dose to OARs, and lowering the number of oART implementation. This approach offers a promising new technical solution for clinical treatment.