Isodose surface volumes in cervix cancer brachytherapy: Change of practice from standard (Point A) to individualized image guided adaptive (EMBRACE I) brachytherapy. Issue 3 (December 2018)

• Record Type: Journal Article
• Authors: Serban, Monica; Kirisits, Christian; Pötter, Richard; de Leeuw, Astrid; Nkiwane, Karen; Dumas, Isabelle; Nesvacil, Nicole; Swamidas, Jamema; Hudej, Robert; Lowe, Gerry; Hellebust, Taran Paulsen; Menon, Geetha; Oinam, Arun; Bownes, Peter; Oosterveld, Bernard; De Brabandere, Marisol; Koedooder, Kees; Marthinsen, Anne Beate Langeland; Lindegaard, Jacob; Tanderup, Kari
• Is Part Of: Radiotherapy and oncology. Volume 129:Issue 3(2018)
• Page Start: 567
• Page End: 574
• Publication Date: 2018-12
• Subjects: α/β Alpha beta ratio -- BT Brachytherapy -- CT Computed tomography -- CTVHR High-risk clinical target volume -- CTVIR Intermediate-risk clinical target volume -- dref Reference fractional physical dose level -- DVH Dose–volume histogram -- EBRT External beam radiotherapy -- EQD2 Biological equivalent dose in 2 Gy fractions -- ESGO-ESTRO-ESP European Society of Gynaecological Oncology – European Society for Radiotherapy and Oncology – European Society of Pathology -- FIGO Fédération Internationale de Gynécologie Obstétrique -- GEC-ESTRO Groupe Européen de Curiethérapie and European Society for Radiotherapy and Oncology -- GTV Gross tumour volume -- HDR High dose rate -- HWT Height, width and thickness -- IC/IS Intracavitary/Interstitial -- ICRU International Commission on Radiation Units -- IGABT Image guided adaptive brachytherapy -- ISV Isodose surface volume -- MRI Magnetic resonance imaging -- OAR Organ at risk -- PDR Pulsed dose rate -- T1/2 Repair half time -- TPS Treatment planning system -- T&R Tandem and ring -- T&O Tandem and ovoids -- TRAK Total Reference Air Kerma; Cervical cancer -- Isodose surface volume -- TRAK -- Point A -- Standard loading brachytherapy -- Magnetic resonance image guided brachytherapy; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2018.09.002
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: MR-IGABT in cervix cancer improved target coverage and reduced irradiated volumes. ISVs correlated with CTVHR volumes showing dose adaptation with tumour size. From the perspective of normal tissue complications PDR was more sparing than HDR. Larger EBRT doses of 50 Gy increased the irradiated volumes at doses of 60 Gy. Abstract: Purpose: To investigate the isodose surface volumes ( ISVs ) for 85, 75 and 60 Gy EQD2 for locally advanced cervix cancer patients. Materials and methods: 1201 patients accrued in the EMBRACE I study were analysed. External beam radiotherapy (EBRT) with concomitant chemotherapy was followed by MR based image-guided adaptive brachytherapy (MR-IGABT). ISVs were calculated using a predictive model based on Total Reference Air Kerma and compared to Point A-standard loading systems. Influence of fractionation schemes and dose rates was evaluated through comparison of ISVs for α / β 10 Gy and 3 Gy. Results: Median V85 Gy, V75 Gy and V60 Gy EQD210 were 72 cm 3, 100 cm 3 and 233 cm 3, respectively. Median V85 Gy EQD210 was 23% smaller than in standard 85 Gy prescription to Point A. For small (<25 cm 3 ), intermediate (25–35 cm 3 ) and large (>35 cm 3 ) CTVHR volumes, the V85 Gy was 57 cm 3, 70 cm 3 and 89 cm 3, respectively. In 38% of EMBRACE patients the V85 Gy was similar to standard plans with 75–85 Gy to Point A. 41% of patients had V85 Gy smaller than standard plans receiving 75 Gy at Point A, while 21% of patients had V85 Gy larger than standard plans receiving 85 Gy at Point A. Conclusions: MR-IGABT and individualized dose prescription during EMBRACE I resulted in improved target dose coverage and decreased ISVs compared to standard plans used with classical Point A based brachytherapy. The ISVs depended strongly on CTVHR volume which demonstrates that dose adaptation was performed per individual tumour size and response during EBRT.