A study to assess the feasibility of using CT (±diagnostic MRI) instead of MRI at brachytherapy in image guided brachytherapy in cervical cancer

PurposeComputed tomography (CT) is inferior to magnetic resonance imaging (MRI) in cervical tumor delineation, but similar in identification of organs at risk (OAR). The trend to over-estimate high-risk and low-risk clinical target volume (HRCTV, IRCTV) on CT can lead to under-estimation of dose received by 90% (D90) of the ‘actual’ CTV. This study aims to evaluate whether CT-guided planning delivers adequate dose to the ‘actual’ targets while spares the OAR similarly.Material and methodsMRI-guided high-dose-rate image-guided brachytherapy (IGBT) was performed in 11 patients. The pre-brachytherapy CTs were retrospectively contoured to generate CT-guided plans. MRI-based contours (HRCTVmri, IRCTVmri, bladdermri, rectummri, and sigmoidmri) were fused to CT plans for dosimetric comparison with MRI-guided plans. Paired 2-tailed t-test and Wilcoxon signed-rank test were used to analyze data.Results63.6% of CT plans achieved the HRCTVmriD90 constraint (≥ 7.2 Gy in one fraction), compared with 90.9% for MRI plans. > 90% of both modalities achieved the OAR’s constraints (EMBRACE). The percentage of CT and MRI plans that achieved the aims (EMBRACE II) for bladder, rectum, and sigmoid were 36.4% vs. 81.8%, 63.6% vs. 63.6%, and 72.7% vs. 72.7%, respectively. There were no statistically significant differences in HRCTVmriD90, IRCTVmriD90, or dose received by the most exposed 2 cm3 (D2cc) of OARmri between the modalities. Excluding the CT plans not achieving HRCTVmriD90 constraint, there were significant increase in bladdermriD2cc, rectummriD2cc, and sigmoidmriD2cc, compared with MRI plans (0.9 Gy/Fr, 95% CI 0.2-1.5, p = 0.018; 0.9 Gy/Fr, 95% CI 0.3-1.4, p = 0.009; 0.5 Gy/Fr, 95% CI 0.2-0.9, p = 0.027, respectively).ConclusionsMRI-based IGBT remains the gold standard. CT planning may compromise HRCTVmriD90 or increase OARmriD2cc, which could decrease local control or increase treatment toxicity.

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“…Bhavana et al . showed similar findings, with the mean difference in dose per fraction less than 1 Gy [ 8 ].…”

Section: Purposementioning

confidence: 53%

“…Past studies have shown that CT-delineated HRCTV (HRCTV ct ) is statistically different from MRI-delineated HRCTV (HRCTV mri ) , even with pre-planning MRI [ 3 , 6 , 7 , 8 , 9 , 10 ]. Such volumetric difference has translated into change in HRCTV D 90 , while dose to OAR show no statistical difference.…”

Section: Purposementioning

confidence: 99%

Throwing the dart blind-folded: comparison of computed tomography versus magnetic resonance imaging-guided brachytherapy for cervical cancer with regard to dose received by the ‘actual’ targets and organs at risk

Yip

Wong

Lee

et al. 2017

jcb

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“…Viswanathan et al proved that the HRCTVct D90 in CT-based plans is statistically lower than the HRCTVmri D90 in MRI guided plans, with mean doses per fraction of 6.7 Gy vs. 8.7 Gy, respectively [ 25 ]. Bhavana et al showed similar findings, with the mean difference in dose per fraction less than 1 Gy [ 26 ].…”

Section: Image Guidance Target Definition and Treatment Adaptatiomentioning

confidence: 65%

“…Past studies have shown that high-risk clinical target volumes (HRCTVs) in cervix tumors delineated by CT (HRCTVct) are statistically different from MRI-delineated HRCTVs (HRCTVmri), even with pre-planning MRI [ 24 , 26 , 27 , 28 , 29 ]. Such volumetric differences have translated into change in HRCTV D90, while the dose to OAR shows no statistical difference.…”

Section: Image Guidance Target Definition and Treatment Adaptatiomentioning

confidence: 99%

Quality Assurance in Modern Gynecological HDR-Brachytherapy (Interventional Radiotherapy): Clinical Considerations and Comments

Soror

Siebert

Lancellotta

et al. 2021

Cancers

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The use of brachytherapy (interventional radiotherapy) in the treatment of gynecological cancers is a crucial element in both definitive and adjuvant settings. The recent developments in high-dose rate remote afterloaders, modern applicators, treatment-planning software, image guidance, and dose monitoring systems have led to improvement in the local control rates and in some cases improved the survival rates. The development of these highly advanced and complicated treatment modalities has been accompanied by challenges, which have made the existence of quality assurance protocols a must to ensure the integrity of the treatment process. Quality assurance aims at standardizing the technical and clinical procedures involved in the treatment of patients, which could eventually decrease the source of uncertainties whether technical (source/equipment related) or clinical. This commentary review sheds light (from a clinical point of view) on some potential sources of uncertainties associated with the use of modern brachytherapy in the treatment of gynecological cancers.

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“…Rai et al . [ 22 ] reported that the height was significantly underestimated in CTV HR -CT contours; however, the statistics were similar between the heights of CT + MRI at diagnosis (CTV HR -CT dMRI ) and CT + MRI at BT (CTV HR -MR). Viswanathan et al .…”

Section: Discussionmentioning

confidence: 93%

Comparison of computed tomography- and magnetic resonance imaging-based target delineation for cervical cancer brachytherapy

Wang¹,

Bu²,

Wu³

et al. 2020

jcb

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Purpose The objective of this study was to compare and assess the accuracy of computed tomography (CT)-based target delineation with that of magnetic resonance imaging (MRI)-based on high-dose-rate brachytherapy (HDR-BT) for patients with cervical cancer. Material and methods Data of 20 patients with locally advanced cervical cancer were collected and evaluated. Dimensions, conformity, and dose parameters of high-risk clinical target volume (CTV HR ) as well as D 0.1cc , D 1cc , and D 2cc of organs at risk (OARs) based on MRI were compared with those based on CT. Results Average age of 20 patients included was 57.8 years. Width, thickness, and volumes of CT-based CTV HR (CTV HR -CT) were significantly overestimated compared with those of MRI-based CTV HR (CTV HR -MR). Mean values of dice similarity coefficient (DSC), Hausdorff distance (HD), and centroid distance (ΔV) of CTV HR were 0.82 cm, 0.96 cm, and 0.35 cm, respectively. Dose values of CTV HR -CT were significantly lower compared with those of CTV HR -MR. Concerning OARs, geometrical and dosimetric values on CT were comparable to those on MRI. Conclusions The delineated ranges of CTV HR were significantly over-estimated on CT compared with MRI. D 98 and D 90 of CTV HR -CT were lower than CTV HR -MR. DSC and ΔV of CTV HR and CTV IR were similar to each other; however, there was a difference in terms of HD. CT images regarding pre-BT MR images for delineating were not enough and MRI fusion is still required.

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A study to assess the feasibility of using CT (±diagnostic MRI) instead of MRI at brachytherapy in image guided brachytherapy in cervical cancer

Cited by 7 publications

References 17 publications

Throwing the dart blind-folded: comparison of computed tomography versus magnetic resonance imaging-guided brachytherapy for cervical cancer with regard to dose received by the ‘actual’ targets and organs at risk

Throwing the dart blind-folded: comparison of computed tomography versus magnetic resonance imaging-guided brachytherapy for cervical cancer with regard to dose received by the ‘actual’ targets and organs at risk

Quality Assurance in Modern Gynecological HDR-Brachytherapy (Interventional Radiotherapy): Clinical Considerations and Comments

Comparison of computed tomography- and magnetic resonance imaging-based target delineation for cervical cancer brachytherapy

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