Oral contrast agents lead to underestimation of dose calculation in volumetric-modulated arc therapy planning for pelvic irradiation

Jiang, Hao; Tian, Yuan; Tang, Yu; Wang, Shulian; Jin, Jing; Song, Yi; Liu, Yueping; Fang, Hui; Chen, Bo; Qi, Shuyao; Tang, Yuan; Lu, Ningning; Yang, Yong; Li, Ning; Li, Yexiong

doi:10.1097/cm9.0000000000001025

Cited by 6 publications

(11 citation statements)

References 40 publications

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“…Ercan et al [30] also reported statistically significant dose differences between NCCT-and CCT-based plans for both target volumes and critical structures. Jing et al [20] concluded that oral contrast agents caused clinically significant changes in the dose calculations for the targets and critical structures. Rankine et al [13] reported significant dose discrepancy for critical structures, and Burridge et al [34] found a considerable increase in MU settings due to contrast agents presence in CCT images.…”

Section: Discussionmentioning

confidence: 99%

“…In a recent VMAT study, Jing et al [20] investigated images from 47 rectal cancer patients. The study concluded that contrast material has a significant effect on calculated doses for the target volumes and critical structures.…”

Section: Introductionmentioning

confidence: 99%

“…The reviewed literature, summarized in Table 1, generally reported limited effect of contrast agents on radiotherapy dose calculations except in a few publications [13,[16][17][18]20,30]. Nevertheless, there was no consensus on the magnitude of these effects or a clear recommendation to utilize contrast-enhanced CT simulation images for radiotherapy dose calculations.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Contrast Agents on Dose Calculations of Volumetric Modulated Arc Radiotherapy Plans for Critical Structures

et al. 2021

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Radiotherapy dose calculation requires accurate Computed Tomography (CT) imaging while tissue delineation may necessitate the use of contrast agents (CA). Acquiring these two sets is a common practice in radiotherapy. This study aims to evaluate the effect of CA on the dose calculations. Two hundred and twenty-six volumetric modulated arc therapy (VMAT) patients that had planning CT with contrast (CCT) and non-contrast CT (NCCT) of different cancer sites (e.g., brain, head, and neck (H&N), chest, abdomen, and pelvis) were evaluated. Treatment plans were recalculated using CCT, then compared to NCCT. The variation in Hounsfield units (HU) and dose distributions for critical structures and target volumes were analyzed using mean HU, mean and maximum relative dose values, D2%, D98%, and 3D gamma analysis. HU variations were statistically significant for most structures. However, this was not clinically significant as the difference in mean HU values was within 30 HU for soft tissue and 50 HU for lungs. Variation in target volumes’ D2% and D98% were insignificant for all sites except brain and nasopharynx. Dose maximum differences were within 2% for the majority of critical structures and target volumes. 3D gamma analysis results revealed that majority of plans satisfied the 2% and 2 mm criteria. CCT may be acquired for VMAT radiotherapy planning purposes instead of NCCT, since there is no clinically significant difference in dose calculations based on either image set.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Effect of Contrast Agents on Dose Calculations of Volumetric Modulated Arc Radiotherapy Plans for Critical Structures

et al. 2021

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“…Jing et al [20] highlighted the underestimation of dose due to intravenous contrast was slight and was moderate due to an oral contrast agent. But, Weber et al [21] reported a slight reduction of dose to the prostate target (0.03-0.14%) and rectum (1.13%) while studying the effects of bladder opacification on dose calculations with a 6-field conformal plan for prostate cancer patients.…”

Section: Discussionmentioning

confidence: 99%

Effect of contrast medium on treatment modalities planned with different photon beam energies: a planning study

Bhushan

Tripathi

Yadav

et al. 2021

Rep Pract Oncol Radiother.

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“…3 Therefore, if the dose calculation is performed in a contrastenhanced CT, there is a concern of dosimetric deviation because the treatment is administered in the absence of contrast. 1,4 In order to avoid this problem, it is a common practice to obtain two CT scans during the same simulation session: one unenhanced and one enhanced. 5 However, it has been described that performing two CT scans during the simulation not only exposes the patient to additional radiation but also reduces the optimisation of resources in the radiation oncology department by extending the simulation time.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric effects of oral contrast in the planning of conventional radiotherapy and IMRT, for rectal cancer treatment

et al. 2022

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Introduction: Contrast media are frequently used during radiation therapy simulation. However, there are concerns about dosimetric variations when dose calculation is done on contrast-enhanced computed tomography (CT). This study evaluates the dosimetric effect of oral contrast during three-dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc radiotherapy (VMAT) planning. Methods: Rectal cancer patients were consecutively enrolled. For each patient, one unenhanced CT and one contrast-enhanced CT were taken using oral and intravenous contrast. Then, a 3D-CRT plan and an Intensity-modulated radiation therapy (IMRT)/VMAT plan were generated in the enhanced CT, and the dose distribution was recalculated in the respective unenhanced CT. The beam intensities were kept the same as for the enhanced CT plans. Finally, the unenhanced and enhanced plans were compared by calculating the gamma index. Results: For 3D-CRT plans, there were statistically significant differences in second phase planning target volume (PTV) D2% (Mean difference (MD) between unenhanced and enhanced CT 0·01 Gy, 95% CI [0·003 to 0·02 Gy]) and in maximum doses to the bladder (MD 0·26 Gy, 95% CI [0·05 to 0·47 Gy]). For IMRT/VMAT plans, there were statistically significant differences in small intestine V45 Gy (MD 3·1 cc, 95% CI [0·81 to 5·4 cc]), bladder V45 Gy (MD 2·9%, 95% CI [1·4 to 4·3%]) and maximum dose to the bladder (MD 0·65 Gy, 95% CI [0·46 Gy to 0·85 Gy]). In addition, for PTV D98% the MD between unenhanced and enhanced CT was 0·22 Gy 95% CI [0·05 to 0·39]. Conclusions: For most of the dose metrics, the differences were not clinically meaningful. The greatest differences were found in VMAT plans, especially in V45 Gy of the small intestine. This difference could lead to an underestimation of dose–volume metrics when the plan is based on an enhanced CT. The use of small bowel oral contrast does not significantly influence dose calculations and may not affect the acceptability of plans when adhering to constraints.

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Oral contrast agents lead to underestimation of dose calculation in volumetric-modulated arc therapy planning for pelvic irradiation

Abstract: Supplemental Digital Content is available in the text

Cited by 6 publications

References 40 publications

The Effect of Contrast Agents on Dose Calculations of Volumetric Modulated Arc Radiotherapy Plans for Critical Structures

The Effect of Contrast Agents on Dose Calculations of Volumetric Modulated Arc Radiotherapy Plans for Critical Structures

Effect of contrast medium on treatment modalities planned with different photon beam energies: a planning study

Dosimetric effects of oral contrast in the planning of conventional radiotherapy and IMRT, for rectal cancer treatment

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