Boost modalities in cervical cancer: dosimetric comparison between intracavitary BT vs. intracavitary + interstitial BT vs. SBRT.
Details
Serval ID
serval:BIB_20A13ADDAFBD
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Boost modalities in cervical cancer: dosimetric comparison between intracavitary BT vs. intracavitary + interstitial BT vs. SBRT.
Journal
Radiation oncology
ISSN
1748-717X (Electronic)
ISSN-L
1748-717X
Publication state
Published
Issued date
28/06/2023
Peer-reviewed
Oui
Volume
18
Number
1
Pages
105
Language
english
Notes
Publication types: Journal Article
Publication Status: epublish
Publication Status: epublish
Abstract
This study compares the dosimetric plans of three distinct boost modalities in cervical cancer (CC): intracavitary (IC) with tandem/ovoids brachytherapy (BT), IC + interstitial (IS) BT, and Stereotactic-Body-Radiotherapy (SBRT). The aim is to determine the dosimetric impact in terms of target coverage and organ at risk (OAR) doses.
24 consecutive IC + IS BT boost treatment plans were retrospectively identified. For each plan included, two additional plans were created: IC-BT and SBRT. Importantly, no planning target volume (PTV) or planning (organ at) risk volume (PRV) margins were generated, therefore all structures were identical for any boost modality. Two different normalizations were performed: (1) Normalization to the target: prescription of 7.1 Gy to the D90% (defined as the minimum dose covering 90%) of the high-risk clinical target volume (HR-CTV); (2) Normalization to the OARs. HR-CTV coverage and OARs sparing were compared. The equivalent doses in 2 Gy fractions (EQD2) of EBRT and BT for CTV-HR and OARs were calculated using the linear-quadratic model with α/β of 10 (EQD2 <sub>10</sub> ) and 3 (EQD2 <sub>3</sub> ), respectively RESULTS: A total of 72 plans were investigated. In the first normalization, the mean EQD2 <sub>3-</sub> D2cc (defined as the minimal dose of the 2 cc) of OAR was significantly higher in the IC-BT plans, and the bladder D2cc hard constraint could not be reached. IC + IS BT leads to a 1 Gy mean absolute decrease of bladder EQD2 <sub>3</sub> -D2cc (relative dose: -19%), allowing to reach the hard constraint. SBRT (without PTV) delivers the lowest EQD2 <sub>3</sub> -D2cc to the OAR. In the second normalization, IC-BT provides a significantly lower dose to the EQD2 <sub>10</sub> -D90% (6.62 Gy) and cannot achieve the coverage goal. SBRT (without PTV) yields the highest dose to the D90% of HR-CTV and a significantly lower EQD2 <sub>10</sub> -D50% and D30%.
The key dosimetric benefit of BT over SBRT without PTV is a significantly higher D50% and D30% in the HR-CTV, which increases the local and conformal dose to the target. IC + IS BT vs. IC-BT provides significantly better target coverage and a lower dose to the OARs, making it the preferred boost modality in CC.
24 consecutive IC + IS BT boost treatment plans were retrospectively identified. For each plan included, two additional plans were created: IC-BT and SBRT. Importantly, no planning target volume (PTV) or planning (organ at) risk volume (PRV) margins were generated, therefore all structures were identical for any boost modality. Two different normalizations were performed: (1) Normalization to the target: prescription of 7.1 Gy to the D90% (defined as the minimum dose covering 90%) of the high-risk clinical target volume (HR-CTV); (2) Normalization to the OARs. HR-CTV coverage and OARs sparing were compared. The equivalent doses in 2 Gy fractions (EQD2) of EBRT and BT for CTV-HR and OARs were calculated using the linear-quadratic model with α/β of 10 (EQD2 <sub>10</sub> ) and 3 (EQD2 <sub>3</sub> ), respectively RESULTS: A total of 72 plans were investigated. In the first normalization, the mean EQD2 <sub>3-</sub> D2cc (defined as the minimal dose of the 2 cc) of OAR was significantly higher in the IC-BT plans, and the bladder D2cc hard constraint could not be reached. IC + IS BT leads to a 1 Gy mean absolute decrease of bladder EQD2 <sub>3</sub> -D2cc (relative dose: -19%), allowing to reach the hard constraint. SBRT (without PTV) delivers the lowest EQD2 <sub>3</sub> -D2cc to the OAR. In the second normalization, IC-BT provides a significantly lower dose to the EQD2 <sub>10</sub> -D90% (6.62 Gy) and cannot achieve the coverage goal. SBRT (without PTV) yields the highest dose to the D90% of HR-CTV and a significantly lower EQD2 <sub>10</sub> -D50% and D30%.
The key dosimetric benefit of BT over SBRT without PTV is a significantly higher D50% and D30% in the HR-CTV, which increases the local and conformal dose to the target. IC + IS BT vs. IC-BT provides significantly better target coverage and a lower dose to the OARs, making it the preferred boost modality in CC.
Keywords
Humans, Female, Uterine Cervical Neoplasms/radiotherapy, Brachytherapy, Radiosurgery, Retrospective Studies, Linear Models, Boost modalities, Cervical Cancer, Stereotactic body Radiotherapy
Pubmed
Web of science
Open Access
Yes
Create date
29/06/2023 14:58
Last modification date
09/12/2023 8:02
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