The clinical application of in vivo dosimetry for gynaecological brachytherapy: A scoping review

Brachytherapy is a key treatment for gynaecological malignancies, delivering high doses to the tumour volume whilst sparing nearby normal tissues due to its steep dose gradient. Accuracy is imperative as small shifts can lead to clinically significant under- or over-dosing of the target volume or organs at risk (OARs), respectively. Independent verification of dose delivered during brachytherapy is not routinely performed but it is important to identify gross errors and define action thresholds to guide inter-fraction treatment decisions. In vivo dosimetry (IVD) is one strategy for improving accuracy and identifying potential errors. Despite promising phantom work, clinical application of IVD is lacking. A literature search was performed using Medline and EMBASE without date limits and based on the PICO framework to evaluate the clinical application of IVD in gynaecological brachytherapy. After screening of titles and abstracts, full text papers were reviewed and 28 studies were identified. Several dosimeters were utilised and measurements were typically taken from the rectum, bladder, vagina and within interstitial catheters. Significant differences between calculated and measured dose were attributed to geometric shifts. The studies reviewed demonstrated the feasibility of IVD in brachytherapy for dose verification but further work is required before IVD can be used to optimise treatment. The purpose of this scoping review is to investigate the clinical application of IVD in gynaecological brachytherapy, understand its challenges and identify the steps required to facilitate integration into everyday clinical practice.