Comparison of Online-Onboard Adaptive Intensity-Modulated Radiation Therapy or Volumetric-Modulated Arc Radiotherapy With Image-Guided Radiotherapy for Patients With Gynecologic Tumors in Dependence on Fractionation and the Planning Target Volume Margin

Abstract

ImportancePatients with newly diagnosed locally advanced cervical carcinomas or recurrences after surgery undergoing radiochemotherapy whose tumor is unsuited for a brachytherapy boost need high-dose percutaneous radiotherapy with small margins to compensate for clinical target volume deformations and set-up errors. Cone-beam computed tomography–based online adaptive radiotherapy (ART) has the potential to reduce planning target volume (PTV) margins below 5 mm for these tumors.ObjectiveTo compare online ART technologies with image-guided radiotherapy (IGRT) for gynecologic tumors.Design, Setting, and ParticipantsThis comparative effectiveness study comprised all 7 consecutive patients with gynecologic tumors who were treated with ART with artificial intelligence segmentation from January to May 2022 at the West German Cancer Center. All adapted treatment plans were reviewed for the new scenario of organs at risk and target volume. Dose distributions of adapted and scheduled plans optimized on the initial planning computed tomography scan were compared.ExposureOnline ART for gynecologic tumors.Main Outcomes and MeasuresTarget dose coverage with ART compared with IGRT for PTV margins of 5 mm or less in terms of the generalized equivalent uniform dose (gEUD) without increasing the gEUD for the organs at risk (bladder and rectum).ResultsThe first 10 treatment series among 7 patients (mean [SD] age, 65.7 [16.5] years) with gynecologic tumors from a prospective observational trial performed with ART were compared with IGRT. For a clinical PTV margin of 5 mm, IGRT was associated with a median gEUD decrease in the interfractional clinical target volume of −1.5% (90% CI, −31.8% to 2.9%) for all fractions in comparison with the planned dose distribution. Online ART was associated with a decrease of −0.02% (90% CI, −3.2% to 1.5%), which was less than the decrease with IGRT (P < .001). This was not associated with an increase in the gEUD for the bladder or rectum. For a PTV margin of 0 mm, the median gEUD deviation with IGRT was −13.1% (90% CI, −47.9% to 1.6%) compared with 0.1% (90% CI, −2.3% to 6.6%) with ART (P < .001). The benefit associated with ART was larger for a PTV margin of 0 mm than of 5 mm (P = .004) due to spreading of the cold spot at the clinical target volume margin from fraction to fraction with a median SD of 2.4 cm (90% CI, 1.9-3.4 cm) for all patients.Conclusions and RelevanceThis study suggests that ART is associated with an improvement in the percentage deviation of gEUD for the interfractional clinical target volume compared with IGRT. As the gain of ART depends on fractionation and PTV margin, a strategy is proposed here to switch from IGRT to ART, if the delivered gEUD distribution becomes unfavorable in comparison with the expected distribution during the course of treatment.

Adaptive Radiotherapy: Next-Generation Radiotherapy

“…Guberina et al 2023 found that non-adapted treatments resulted in a median CTV coverage loss of 11.4%, whereas adapted treatments only had a loss of 0.6%. No grade 3 toxicity events were observed during the study, which had a median follow-up period of 4 months [ 10 ].…”

“…Over the past many decades, radiotherapy has evolved in sophistication to achieve increasingly improved accuracy and precision. With these advancements, handling daily anatomical changes through ART became necessary owing to the capability to conformally and accurately target the tumor and the ever-shrinking margins [ 9 , 10 ].…”

“…Online ART also relies on on-couch volumetric imaging techniques, such as CBCT, MRI, and PET imaging, which allow for frequent and immediate visualization of the patient’s anatomy and tumor position before and during each treatment session [ 10 , 15 ]. State-of-the-art online ART systems utilize advanced treatment planning software that can quickly process imaging data and make in-session adjustments to the treatment plan.…”

Daily AI-Based Treatment Adaptation under Weekly Offline MR Guidance in Chemoradiotherapy for Cervical Cancer 1: The AIM-C1 Trial

“…The first results in cervical cancer patients demonstrated the feasibility and dosimteric benefits of the ETHOS radiotherapy system [25][26][27][28]. However, these studies were partly from in silico trials, and clinical results are still missing.…”

Experimental Examination of Conventional, Semi-Automatic, and Automatic Volumetry Tools for Segmentation of Pulmonary Nodules in a Phantom Study

“…While automatic contouring of organs at risk (OAR) has been extensively examined and is increasingly established in radiation therapy departments [1], the automatic delineation of targets remains a significant challenge, even in the context of online onboard Diagnostics 2024, 14, 28 2 of 10 adaptive planning [2]. Accurate target definition requires expertise to convert recommendations and clinical information into a high precision treatment plan.…”