DOSIMETRIC COMPARISON OF DIFFERENT ARC TREATMENT PLANS IN PATIENTS WITH BILATERAL SURRENAL METASTASES

Year 2025, Volume: 26 Issue: 4, 326 - 331, 13.10.2025

Taha Erdoğan , Düriye Öztürk

https://doi.org/10.18229/kocatepetip.1524592

Abstract

OBJECTIVE: A retrospective study was designed for dosimetric comparison of different arc treatment plans to investigate the efficacy and safety of ablative stereotactic body radiotherapy (SBRT) in the treatment of bilateral adrenal gland metastases (AGM).
MATERIAL AND METHODS: In 14 patients (12 males, 2 females) with AGM of 84 and Karnofsky performance score ≥70, we optimised single-volumetric arc therapy (S-VMAT) and multiple-volumetric arc therapy (M-VMAT) isocentric arc VMAT for SBRT treatments from October 2006 to January 2017. The maximum and mean organ doses in specific volumes of critical organs were examined. The differences between the monitor unit values were statistically analysed.
RESULTS: S-VMAT plans had a better dose conformity index (COI) than M-VMAT plans, with a relative improvement of 4% (p=0.02). Similarly, S-VMAT plans had a significantly higher homogeneity index (HI) than M-VMAT plans, with a relative improvement of 13.8% (p=0.001). S-VMAT plans resulted in better UI and GI compared with M-VMAT, with relative improvements of 8.7% and 6.9% respectively (p=0.02). Mean MU per fraction was 2755.21±388.72 in S-VMAT and 4848.79±491.06 in M-VMAT. The S-VMAT schedules reduced MU per fraction used by 76% (p=0.01).
CONCLUSIONS: S-VMAT has significantly protected OARs without compromising target coverage compared to the M-VMAT technique. Although the average time to prepare an S-VMAT plan is approximately four times that of an M-VMAT plan, this plan has demonstrated several inherent advantages, including a shorter treatment duration and fewer monitor units (MU). Consequently, it has reduced the quality of M-VMAT plans and caused an increase in the doses to organs at risk (OARs). Furthermore, as it has also caused an increase in the total number of MUs, the treatment duration has been extended and the number of MUs delivered to the patient has increased.

Keywords

Bilateral , Adrenal Gland Metastases , SBRT , VMAT

Ethical Statement

This study was approved by the Afyonkarahisar Health Sciences University’s Clinical Research Ethics Committee with the decision no. 2021/04 and dated 04.02.2021.

Thanks

I would like to thank Afyonkarahisar University of Health Sciences Health Application and Research Center, who contributed to the use of clinical data and treatment devices for this study, and to the Afyonkarahisar University of Health Sciences Health Application and Research Center, M.Sc. Phys. Eng. Özveri TUĞLU ÖLÇER and M.Sc. Phys. Eng. I would like to thank Feyza SAVAŞ AKBULUT.

BİLATERAL SÜRRENAL METASTAZLI HASTALARDA FARKLI ARK TEDAVİ PLANLARININ DOZİMETRİK KARŞILAŞTIRMASI

Abstract

AMAÇ: Bilateral adrenal bez metastazlarının (AGM) tedavisinde ablatif stereotaktik vücut radyoterapisinin (SBRT) etkinliğini ve güvenilirliğini araştırmak için farklı ark tedavi planlarının dozimetrik karşılaştırılması amacıyla retrospektif bir çalışma tasarlanmıştır.
GEREÇ VE YÖNTEM: Ekim 2006'dan Ocak 2017'ye kadar AGM 84 ve Karnofsky performans skoru ≥70 olan 14 hastada (12 erkek, 2 kadın) tekli (S-VMAT) ve çoklu (M-VMAT) izocenter ark VMAT'ı SBRT tedavileri için optimize edilmiştir. Kritik organlar olarak böbrek, karaciğer, omurilik, aort, mide, duodenum, pankreas, deri ve tüm vücudun belirli hacimlerdeki maksimum dozları, ortalama dozları ve maksimum organ dozları incelenmiştir. Ayrıca tedavi planlama sisteminde tedavi süresine karşılık gelen MonitorUnit değerleri arasındaki farklar istatistiksel olarak analiz edilmiştir.
BULGULAR: S-VMAT planları, M-VMAT ile karşılaştırıldığında %4'lük bir nispi iyileşme ile daha iyi bir doz coverage indeksi (COI) ile sonuçlanmıştır. Bu fark anlamlıydı (p=0.02). Benzer şekilde, S-VMAT planları, %13,8'lik bir göreli iyileşme ile M-VMAT'tan önemli ölçüde daha yüksek bir HI sergilemiştir (p=0.001). S-VMAT planları, M-VMAT'a kıyasla sırasıyla %8,7 ve %6,9 oranında daha iyi bir UI ve GI ile sonuçlanmıştır (p=0.02). Fraksiyon başına ortalama MU değerleri S-VMAT'ta 2755,21±388,72 ve M-VMAT'ta 4848,79±491,06 olarak hesaplanmıştır. S-VMAT planları, fraksiyon başına MU'larda %76 azalma ile sonuçlanmıştır (p=0.01).
SONUÇ: S-VMAT, M-VMAT tekniğine kıyasla hedef kapsama alanından taviz vermeden OAR'ları önemli ölçüde korumuştur. Bir S-VMAT planı hazırlamak için ortalama süre, bir M-VMAT planı hazırlamak için ortalama sürenin yaklaşık dört katı olmasına rağmen, bu plan, daha kısa tedavi süresi ve daha az monitör unit (MU) dahil olmak üzere birçok doğal avantaj sergilemiştir. Sonuç olarak M-VMAT plan kalitesini düşürmekte ve risk altındaki organların (OAR) dozlarında artışa sebep olmuştur. Ayrıca toplam MU sayısında da artışa sebep olduğu için tedavi süresi uzamakta ve hastaya verilen MU artmıştır.

Keywords

Bilateral , Adrenal Gland Metastases , SBRT , VMAT

Ethical Statement

Bu çalışma Afyonkarahisar Sağlık Bilimleri Üniversitesi Klinik Araştırmalar Etik Kurulu tarafından 04.02.2021 tarih ve 2021/04 sayılı karar ile onaylanmıştır.

Thanks

Bu çalışma için klinik verilerin ve tedavi cihazlarının kullanılmasına katkı sağlayan Afyonkarahisar Sağlık Bilimleri Üniversitesi Sağlık Uygulama ve Araştırma Merkezi'ne, Yüksek Fizik Müh. Özveri TUĞLU ÖLÇER'e ve Yüksek Fizik Müh. Feyza SAVAŞ AKBULUT'a teşekkür ederim.

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