Technical parameters of computed tomography used in radiotherapy planning:
a structured literature review
DOI:
https://doi.org/10.15448/1980-6108.2026.1.49155Keywords:
radiotherapy, computed tomography, imaging, treatment planning, optimization, slice thickness.Abstract
The use of Computed Tomography (CT) in radiotherapy planning is a routine practice across different healthcare facilities, regardless of their level of complexity. This is thanks to the diagnostic value of CT in delineating the volumes and areas to be irradiated. However, the parameters used in radiotherapy planning are not always readily available in the literature. Therefore, this study aimed to systematically review the literature on the use of CT for treatment planning in Radiotherapy and to propose a usage protocol. Methods: The search strategy was developed using descriptors in English and Portuguese, Radiotherapy, Computed Tomography, Treatment Planning, Imaging, Optimization and Slice Thickness and applied to the PubMed and Scopus databases. The Rayyan review management system was used to assist researchers in the blind selection of articles. After applying inclusion and exclusion criteria, 21 articles were selected for full-text reading. Results: The technical parameters for CT acquisition in radiotherapy planning are generally standardized, using a voltage of 120 kV and a slice thickness between 2 and 3 mm, ensuring greater accuracy in Hounsfield Unit (HU) conversion and reproducibility in the delineation of target volumes and organs at risk. However, some centers use slice thicknesses of up to 5 mm. The tube current, controlled by the automatic exposure control (AEC) system, typically ranges from 370 to 400 mA and can reach up to 685 mA. Conclusions: The CT technical parameters most commonly used in radiotherapy planning include a voltage of 120 kV, a tube current between 370 and 400 mA, and a slice thickness of 2 to 3 mm, constituting a consolidated practice that ensures safety and effectiveness. In the absence of specific institutional protocols, it is recommended that centers adopt these values, adjusting them to clinical needs and developing tailored guidelines to enhance the quality and safety of examinations. It was also observed that only 1 study cited the tube rotation speed
and pitch, parameters relevant to dose calculation, revealing a gap in the literature and highlighting the need for more detailed recommendations for different clinical contexts.
Downloads
References
1. Wood TJ, Davis AT, Earley J, Edyvean S, Findlay U, Lindsay R, et al. IPEM topical report: The first UK survey of dose indices from radiotherapy treatment planning computed tomography scans for adult patients. Phys Med Biol. 2018;63(18):185008. https://doi.org/10.1088/1361-6560/aacc87
2. Adachi T, Nakamura M, Matsuo Y, et al. Prospective external validation of radiomics-based predictive model of distant metastasis after dynamic tumor tracking stereotactic body radiation therapy in patients with nonsmall-cell lung cancer: A multi-institutional analysis. J Appl Clin Med Phys. 2024;25(10):e14475. https://doi.org/10.1002/acm2.14475
3. Schmidt RM, Delgadillo R, Ford JC, Padgett KR, Studenski M, Abramowitz MC, et al. Assessment of CT to CBCT contour mapping for radiomic feature analysis in prostate cancer. Sci Rep. 2021;11:227-37. https://doi.org/10.1038/s41598-021-02154-w
4. Khamfongkhruea C, Thongsawad S, Tannanonta C, Chamchod S. Comparison of CT images with average intensity projection, free breathing, and mid-ventilation for dose calculation in lung cancer. J Appl Clin Med Phys. 2017;18(2):26-36. https://doi.org/10.1002/acm2.12037
5. Toussaint A, Richter A, Mantel F, Flickinger JC, Grills IS, Tyagi N, et al. Variability in spine radiosurgery treatment planning – results of an international multiinstitutional study. Radiat Oncol. 2016;11(57):1-9. https://doi.org/10.1186/s13014-016-0631-9
6. Sabarudin A, Mustafa Z, Nassir KM, Hamid HA, Sun Z. Radiation dose reduction in thoracic and abdomen–pelvic CT using tube current modulation: a phantom study. J Appl Clin Med Phys. 2014;16(1):319-28. https://doi.org/10.1120/jacmp.v16i1.5135
7. Sarawagi R, Sharma DN, Kumar R, Subramani V, Kumar S, Pandey R, et al. Positron emission tomography versus computed tomography-guided intracavitary brachytherapy for locally advanced cervical cancer: A prospective randomized study. J Cancer Res Ther. 2025;21(1):151-5. https://doi.org/10.4103/jcrt.jcrt_1582_24
8. Eekers DB, Ven LI, Roelofs E, Postma A, Alapetite C, Burnet NG, et al. The EPTN consensus-based atlas for CT- and MR-based contouring in neurooncology. Radiother Oncol. 2018;128:37-43. https://doi.org/10.1016/j.radonc.2017.12.013
9. Yan M, Zhang Z, Tian J, Yu J, Dekker A, Ruysscher DD, et al. Whole lung radiomic features are associated with overall survival in patients with locally advanced non-small cell lung cancer treated with definitive radiotherapy. Radiat Oncol. 2025;20(9):e2583. https://doi.org/10.1186/s13014-025-02583-1
10. Sapienza LG, Flosi A, Aiza A, Pellizzon ACA, Chojniak R, Baiocchi G. Volumetric (3D) bladder dose parameters are more reproducible than point (2D) dose parameters in vaginal vault high-dose-rate brachytherapy. Sci Rep. 2016;6:28074. https://doi.org/10.1038/srep28074
11. Vogin G, Hettal L, Bartau C, Thariat J, Claeys MV, Peyraga G, et al. Cranial organs at risk delineation: heterogenous practices in radiotherapy planning. Radiat Oncol. 2021;16(26):1-11. https://doi.org/10.1186/s13014-021-01756-y
12. Van Wijk Y, Vanneste BGL, Walsh S, Meer SV, Ramaekers B, Van Elmpt W, et al. Development of a virtual spacer to support the decision for the placement of an implantable rectum spacer for prostate cancer radiotherapy: comparison of dose, toxicity and costeffectiveness. Radiother Oncol. 2017;125(1):107-112. https://doi.org/10.1016/j.radonc.2017.07.026
13. Kataria T, Gupta D, Basu T, Gupta S, Goyal S, Banerjee S, et al. Simple diagrammatic approach to delineate duodenum on a radiotherapy planning CT scan. Br J Radiol. 2016;89(1061):20150661. https://doi.org/10.1259/bjr.20150661
14. Sarolkar A, Singh SN, Bagdare P, Bhandari V, Lodi AI, Moharir S. To evaluate volume changes on computerized tomography scan and magnetic resonance imagingbased delineation during radiotherapy treatment planning in prostate cancer. J Cancer Res Ther. 2021;17(2):379-82. https://doi.org/10.4103/jcrt.JCRT_839_18
15. Karki K, Saraiya S, Hugo GD, Mukhopadhyay N, Jan N, Schuster J, et al. Variabilities of MRI-, CT- and PET-CT-based tumor and lymph node delineations for lung cancer radiotherapy planning. Int J Radiat Oncol Biol Phys. 2017;99(1):80-9. https://doi.org/10.1016/j.ijrobp.2017.05.002
16. Maheshwari G, Dhanawat A, Kumar HS, Sharma N, Jakhar SL. Clinical and dosimetric impact of adaptive intensity-modulated radiotherapy in locally advanced head-and-neck cancer. J Cancer Res Ther. 2020;16(3):600-4. https://doi.org/10.4103/jcrt.JCRT_928_19
17. Guo Y, Li J, Zhang P, Shao Q, Xu M, Li Y. Comparative evaluation of target volumes defined by deformable and rigid registration of diagnostic PET/CT to planning CT in primary esophageal cancer. Medicine (Baltimore). 2017;96(1):e5528. https://doi.org/10.1097/MD.0000000000005528
18. Machiels M, Jin P, Van Gurp CH, Van Hooft JE, Alderliesten T, Hulshof MCCM. Comparison of carinabased versus bony anatomy-based registration for setup verification in esophageal cancer radiotherapy. Radiat Oncol. 2018;13(48):1-9. https://doi.org/10.1186/s13014-018-0986-1
19. Kim H, Kim J. Evaluation of the anatomical parameters for normal tissue sparing in the prone position radiotherapy with small sized left breasts. Oncotarget. 2016;7(44):72211-8. https://doi.org/10.18632/oncotarget.12662
20. Wang X, Fargier-Bochaton O, Dipasquale G, Laouiti M, Kountouri M, Gorobets O, et al. Is prone free breathing better than supine deep inspiration breathhold for left whole-breast radiotherapy? A dosimetric analysis. Strahlenther Onkol. 2021;197:317-31. https://doi.org/10.1007/s00066-020-01731-8
21. Koide Y, Shimizu H, Miyauchi R, Haimoto S, Tanaka H, Watanabe Y, et al. Fully automated rigid image registration versus human registration in postoperative spine stereotactic body radiation therapy: a multicenter non-inferiority study. J Radiat Res. 2022;63(1):115-https://doi.org/10.1093/jrr/rrab113
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Alexandre Maciel Rolim, Nádila Isis Gonçalves da Fonseca, Florencia Agustina Perez Gutierrez, Apolinário de Oliveira Botelho, Daiane Cristini Barbosa de Souza
This work is licensed under a Creative Commons Attribution 4.0 International License.
