Efficacy of Thermoformable Vacuum Head Cushion on Set-up Accuracy in IMRT of Head & Neck and Brain Tumors

Abstract

Aim: An effective immobilization is warranted to minimize set up deviations while treating head & neck (HN) and brain tumors with intensity modulated radiotherapy (IMRT). In this study we evaluated the effectiveness of thermoformable vacuum head cushion (TVHC) on immobilization of these patients via weekly electronic digital port films (EDPF). Material and Method: Twenty patients treated with IMRT for HN and Brain tumors were enrolled in the study. Thermoplastic mask with additional standard plastic head rest (n:10) in Group A or TVHC supporting the head and neck region (n:10) in Group B were used for immobilization. Weekly EDPF images were obtained on the linear accelerator. Set-up displacements in latero-medial, anteroposterior and cranio-caudal directions in these images were compared with variation data of first treatment. Results: When each group was analyzed in terms of deviations in all 3 directions, deviations calculated in anteroposterior and craniocaudal directions were significantly higher for TVHC group (p:0.039 and p:0.002 respectively). Deviations >4mm in all three directions were also analyzed and similarly, higher rates of >4mm deviations were recorded for TVHC group in anteroposterior and craniocaudal directions (p:0.023 and p:<0.001 respectively) which of both were also statistically significant. Conclusion: We found that TVHC utilization in HN and brain IMRT for immobilization leads to significantly higher set-up deviations so future investigations with larger patient populations and evaluating set up accuracy via more sensitive alignments are needed to suggest TVHC for utilization in daily clinical practice.

Keywords

• Thermoformable vacuum head cushion
• positioning accuracy
• head and neck cancer
• IMRT

Baş-Boyun ve Beyin Tümörü IMRT Uygulamasında Vakumlu Boyun Yastığı (VBY)’ nın Set Up Doğruluğuna Katkısı

Abstract

Amaç: Baş-boyun ve beyin tümörlerinde uygulanacak lokal radyoterapi sırasında eşlik eden kritik normal dokulara verilebilecek zararın en aza indirilmesi açısından özel planlama tekniklerine ve ideal sabitleme ekipmanlarına gerek duyulmaktadır. Çalışmamızda baş-boyun ve beyin tümörü tanısı ile radyoterapi uygulanan hastalarda ek sabitleme ekipmanı olarak kullandığımız Vakumlu Boyun Yastığı (VBY)‘nın etkinliğinin tedavi süresince alınan haftalık port filmleri ile değerlendirilmesi amaçlandı. Materyal Metod: Kliniğimizde baş-boyun veya beyin tümörü tanısıyla uygulanan küratif/adjuvan radyoterapi sırasında VBY kullanılan ve kullanılmayan 10 hastanın haftalık portları VBY kullanılan (Grup A) ve kullanılmayan (Grup B) olmak üzere iki gruba ayrılarak değerlendirildi. Her hastanın 7 port görüntüsünde longitudinal, lateral ve vertikal eksendeki verisinin set-up değerlerine göre farkları mutlak değer olarak kaydedildi. Her iki gruptaki kaydırma değerleri ve >4mm kaydırma yüzdeleri değerlendirildi. Bulgular: Çalışmaya dahil edilen toplam 20 hastanın tanıları 14 nazofarenks, 2 GBM, 2 dil, 1 larenks, 1 sert damak tümörü şeklinde idi. Her iki grup kaydırma miktarları açısından değerlendirildiğinde vertikal ve longitudinal eksendeki kaydırma düzeylerinin VBY kullanılan hastalarda anlamlı oranda yüksek olduğu saptandı (sırasıyla p:0,039 ve p:0,002). Hastalarda > 4mm düzeyindeki kayma oranları da yine vertikal ve longitudinal eksende VBY kullanılan hastalarda anlamlı oranda yüksek olduğu saptandı (sırasıyla p:0,023 ve p:<0001). Her iki gruptaki fark oranları ve p değerleri Tablo 1 de gösterilmiştir. Sonuç: Hastalarımızda ek sabitleme ekipmanı olarak VBY kullanımının standart yastık kullanımına göre istatistiksel anlamlı oranda daha yüksek kaydırma değerleri ve daha fazla > 4mm kaydırma yüzdesine neden olduğu saptanmıştır. Sonuç olarak baş-boyun ve beyin tümörü radyoterapisinde VBY kullanımının immobilizasyona katkısı gösterilememiştir.

Keywords

• Vakumlu Boyun Yastığı
• pozisyonlama güvenilirliği
• baş boyun kanseri
• IMRT

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