A novel external beam radiotherapy method for cervical cancer patients using virtual straight or bending boost areas; an in-silico feasibility study

Luca Cozzi; Sushil Beriwal; Esa Kuusela; Supriya Chopra; Hester Burger; Nanette Joubert; Antonella Fogliata; Jai Prakash Agarwal; Pat Kupelian

doi:10.1186/s13014-021-01838-x

A novel external beam radiotherapy method for cervical cancer patients using virtual straight or bending boost areas; an in-silico feasibility study

Radiat Oncol. 2021 Jun 14;16(1):110. doi: 10.1186/s13014-021-01838-x.

Authors

Luca Cozzi^{1

2}, Sushil Beriwal³, Esa Kuusela⁴, Supriya Chopra⁵, Hester Burger⁶, Nanette Joubert⁶, Antonella Fogliata⁷, Jai Prakash Agarwal⁵, Pat Kupelian^{8

9}

Affiliations

¹ Radiotherapy and Radiosurgery Department, Humanitas Research Hospital and Cancer Center, Via Manzoni 56, 20089, Milan-Rozzano, Italy. luca.cozzi@humanitas.it.
² Varian Medical Systems, Palo Alto, USA. luca.cozzi@humanitas.it.
³ Department of Radiation Oncology, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, USA.
⁴ Varian Medical Systems Finland, Helsinki, Finland.
⁵ Department of Radiation Oncology, Advanced Centre for Treatment Research and Education in Cancer, Tata Memorial Centre, Homi Bhaba National Institute, Mumbai, India.
⁶ Division of Medical Physics, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa.
⁷ Radiotherapy and Radiosurgery Department, Humanitas Research Hospital and Cancer Center, Via Manzoni 56, 20089, Milan-Rozzano, Italy.
⁸ Varian Medical Systems, Palo Alto, USA.
⁹ Radiation Oncology Dept, University of California, Los Angeles, USA.

Abstract

Aim: To 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.

Methods: Ten 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 D_90% ≥ 30 Gy, V_45Gy ≥ 50-55% and V_60Gy ≥ 30%. The planning objectives for the organs at risk (OAR) were: D_2cm3 ≤ 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.

Results: The D_2cm3 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 V_45Gy = 43.1 ± 7.5% (56.6 ± 5.6%) and V_60Gy = 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 D_90% = 33-35 Gy to the CTV without compromising any constraints to the OARs CONCLUSION: In 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.

Keywords: Cervix uteri cancer; RapidArc; Spatially fractionated radiation therapy; VMAT; Virtual brachytherapy.

MeSH terms

Brachytherapy / methods*
Computer Simulation*
Feasibility Studies
Female
Humans
Organs at Risk / radiation effects*
Prognosis
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Retrospective Studies
Uterine Cervical Neoplasms / pathology
Uterine Cervical Neoplasms / radiotherapy*