The use of modern imaging technologies in radiation therapy of cervical cancer

Abstract

Over the past century, definitive management of unresectable cervical cancer has evolved and currently employs high-dose radiation treatment with teletherapy and intracavitary brachytherapy (ICBT) components, combined with concurrent chemotherapy. Reflecting high disease prevalence among developing nations, the International Federation of Gynecology and Obstetrics (FIGO) staging of cervical cancer relies on clinical assessment, with limited radiographic studies. However, multiple clinicopathologic analyses describe suboptimal correlation between clinical examination findings and pathologic stage. Over the past two decades, systematic evaluation of volumetric and functional imaging modalities including CT, MRI, and PET-CT has refined our ability to define disease extent and provide posttreatment surveillance. Similarly, traditional ICBT techniques relied on two-dimensional (2D) data for evaluation of target dose coverage and offered limited assessment of exposure to critical structures including the bladder, rectum, and sigmoid colon. During the last several years, investigators at leading European centers have enhanced the capabilities of existing ICBT techniques through dose optimization [high-dose rate (HDR) and pulsed dose rate (PDR)] and by incorporating volumetric imaging methods. Early results are encouraging, from both toxicity and tumor control perspectives. These techniques are currently being adopted in multiple centers. Pertinent aspects are summarized in the body of this report.

Adaptive treatment-length optimization in spatiobiologically integrated radiotherapy

“…Interest in spatiobiologically integrated adaptive planning is partly fueled by emerging advances in functional imaging techniques such as positron emission tomography (PET) and magnetic resonance spectroscopic imaging (MRSI). Functional images, at least in principle, allow the treatment planner to noninvasively and quantitatively track biological entities such as tumor cell density and oxygen pressure (which is known to affect radiosensitivity) over the treatment course (Alber et al 2003, Yang and Xing 2005, Stewart and Li 2007, South et al 2008, 2009, Bhatnagar et al 2013, Blanco et al 2015, Langen et al 2015, Baumann et al 2016, Yamamoto et al 2016. The idea is to obtain a new fluence-map by solving a new instance of a spatiobiologically integrated optimization problem using the most recent quantitative information about the tumor's biological condition as input, after each functional image is acquired.…”

Error analysis of applicator position for combined internal/external radiation therapy in cervical cancer

“…However, during radiotherapy, the applicator position is prone to error. If the error is relatively large, the accuracy and effectiveness of the treatment are affected ( 3 – 5 ). Here, we discuss the error in applicator position in after-loading combined radiation therapy for cervical cancer for the first and second sessions to provide valuable reference to enhance the therapeutic effect of irradiation in patients with cervical cancer.…”