Technical note: rtdsm—An open‐source software for radiotherapy dose‐surface map generation and analysis

Abstract

Background Dose‐outcome studies in radiation oncology have historically excluded spatial information due to dose‐volume histograms being the most dominant source of dosimetric information. In recent years, dose‐surface maps (DSMs) have become increasingly popular for characterization of spatial dose distributions and identification of radiosensitive subregions for hollow organs. However, methodological variations and lack of open‐source, publicly offered code‐sharing between research groups have limited reproducibility and wider adoption. Purpose This paper presents rtdsm, an open‐source software for DSM calculation with the intent to improve the reproducibility of and the access to DSM‐based research in medical physics and radiation oncology. Methods A literature review was conducted to identify essential functionalities and prevailing calculation approaches to guide development. The described software has been designed to calculate DSMs from DICOM data with a high degree of user customizability and to facilitate DSM feature analysis. Core functionalities include DSM calculation, equivalent dose conversions, common DSM feature extraction, and simple DSM accumulation. Results A number of use cases were used to qualitatively and quantitatively demonstrate the use and usefulness of rtdsm. Specifically, two DSM slicing methods, planar and noncoplanar, were implemented and tested, and the effects of method choice on output DSMs were demonstrated. An example comparison of DSMs from two different treatments was used to highlight the use cases of various built‐in analysis functions for equivalent dose conversion and DSM feature extraction. Conclusions We developed and implemented rtdsm as a standalone software that provides all essential functionalities required to perform a DSM‐based study. It has been made freely accessible under an open‐source license on Github to encourage collaboration and community use.

The use of dose surface maps as a tool to investigate spatial dose delivery accuracy for the rectum during prostate radiotherapy

“…Generation of DSMs was achieved using rtdsm , an open‐source Python package previously developed by our group for DSM calculation and analysis 26 . For each plan and daily image, rtdsm began by defining slices of the rectum contour orthogonal to its central‐axis path in increments of 3 mm, correcting the orientation of intersecting slices using the approach of Witztum et al 27 .…”

“…Generation of DSMs was achieved using rtdsm, an open-source Python package previously developed by our group for DSM calculation and analysis. 26 For each plan and daily image, rtdsm began by defining slices of the rectum contour orthogonal to its central-axis path in increments of 3 mm, correcting the orientation of intersecting slices using the approach of Witztum et al 27 Next, 45 equiangular points were defined around the outer circumference of each slice and dose was sampled at these points. Finally, each contour was unwrapped along its posterior rectal wall and mapped into a 2D array.…”

More than one way to skin a dose volume: the impact of dose-surface map calculation approach on study reproducibility

“…This allowed us to reproduce the breadth of calculation approaches present in current DSM literature. All DSM calculations were performed using rtdsm, a recently-developed open-source Python package for DSM calculation and analysis (Patrick and Kildea 2022). rtdsm can calculate planar or non-coplanar DSMs using the standard RT-Structure and RT-Dose files from a DICOM-RT-compliant radiotherapy treatment planning system as input.…”