Abstract
AimTo investigate the potential role of a novel spatially fractionated radiation therapy (SFRT) method where heterogeneous dose patterns are created in target areas with virtual rods, straight or curving, of variable position, diameter, separation and alignment personalised to a patient’s anatomy. The images chosen for this study were CT scans acquired for the external beam part of radiotherapy.MethodsTen patients with locally advanced cervical cancer were retrospectively investigated with SFRT. The dose prescription was 30 Gy in 5 fractions to 90% target volume coverage. Peak-and-valley (SFRT_1) and peak-only (SFRT_2) strategies were applied to generate the heterogeneous dose distributions. The planning objectives for the target (CTV) were D90% ≥ 30 Gy, V45Gy ≥ 50–55% and V60Gy ≥ 30%. The planning objectives for the organs at risk (OAR) were: D2cm3 ≤ 23.75 Gy, 17.0 Gy, 19.5 Gy, 17.0 Gy for the bladder, rectum, sigmoid and bowel, respectively. The plan comparison was performed employing the quantitative analysis of the dose-volume histograms.ResultsThe D2cm3 was 22.4 ± 2.0 (22.6 ± 2.1) and 13.9 ± 2.9 (13.2 ± 3.0) for the bladder and the rectum for SFRT_1 (SFRT_2). The results for the sigmoid and the bowel were 2.6 ± 3.1 (2.8 ± 3.0) and 9.1 ± 5.9 (9.7 ± 7.3), respectively. The hotspots in the target volume were V45Gy = 43.1 ± 7.5% (56.6 ± 5.6%) and V60Gy = 15.4 ± 5.6% (26.8 ± 6.6%) for SFRT_1 (SFRT_2). To account for potential uncertainties in the positioning, the dose prescription could be escalated to D90% = 33–35 Gy to the CTV without compromising any constraints to the OARsConclusionIn this dosimetric study, the proposed novel planning technique for boosting the cervix uteri was associated with high-quality plans, respecting constraints for the organs at risk and approaching the level of dose heterogeneity achieved with routine brachytherapy. Based on a sample of 10 patients, the results are promising and might lead to a phase I clinical trial.
Highlights
At the global level, the incidence and mortality of cervical cancer are high with more impact in low-mid income countries (LMICs) due to lack of screening, vaccination against the human papillomavirus, and overall limited access to care [1]
Soft tissue fusion with contrast-enhanced Computed tomography (CT) was performed to facilitate delineation of CTV. Patients were chosen such that their clinical target volumes at brachytherapy were representatives of patients with significant residual disease at the time of brachytherapy such that the impact of these relatively large targets could be studied for both target coverage and organ at risk sparing
The target delineation consisted of the high-risk clinical target volume (CTV), including the primary gross tumour volume and the remaining cervix not infiltrated by the tumour as described in [15]
Summary
The incidence and mortality of cervical cancer are high with more impact in low-mid income countries (LMICs) due to lack of screening, vaccination against the human papillomavirus, and overall limited access to care [1]. Cozzi et al Radiat Oncol (2021) 16:110 standard of care, with the radiotherapy component consisting of external beam treatments followed by brachytherapy (BT, intracavitary ± interstitial). The omission of brachytherapy is associated with detriment in survival [4]. The application of brachytherapy is dependent on two factors: (1) availability of brachytherapy facilities, radioactive brachytherapy sources, and associated experienced clinical teams, and (2) contra-indications to BT, primarily due to very advanced stages of the disease. If any of these two factors apply, it would be desirable to expand the radiotherapeutic options panel with practical techniques
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
