Erken Evre Gloktik Larenks Radyoterapisinde Yoğunluk Ayarlı Ark Tedavisi ve CyberKnife Tekniklerinin Tedavi Planlarının Karşılaştırması

Abstract

Erken Evre Glottic Larenks (EEGL) Kanseri tedavi planlarında iki radyoterapi tekniğini (Robotik tabanlı lineer hızlandırıcı Stereotaktik Beden Radyoterapi (SBRT) ve lineer hızlandırıcı tabanlı Yoğunluk Ayarlı Ark Tedavisi (YAAT)) dozimetrik olarak, hedef hacim ve kritik organ dozları açısından kıyaslamayı amaçladık. EEGL tanısı ile tedavi edilen 15 hastanın retrospektif bilgisayarlı tomografi (BT) görüntüleri kullanıldı. Planlanan tedavi volümü (PTV), larinkse 0.5 cm'lik bir marj vererek oluşturuldu. Her iki tedavi planında da 10 fraksiyonda toplam 45 Gy tedavi dozu tanımlanmıştır. PTV tedavi hacimlerinin %95'inin (D%95) tedavi dozunu alması amaçlanmıştır. Ortalama PTV hacmi 95.56 cm3 (68.8 cm3 - 142.6 cm3) idi. D%98, D%2 ve Dmean değerleri IMAT planında CK planına göre daha düşüktü. CK planlarında ortalama spinal kord maksimum dozu (Dmax), istatistiksel olarak anlamlı derecede düşüktür. Sağ ve sol karotid arterler için Dmax ve Dmean değerleri, IMAT planlarında CK planlarına göre anlamlı derecede düşüktür. Ayrıca tiroid bezinin Dmean değeri, IMAT planlarında CK planlarına göre anlamlı derecede düşüktür. 15 EGL hastasının görüntüleri ile düzenlenmiş tedavi planlarının dozimetrik kıyaslamasında CK planlamasıyla kritik organ dozlarında, özellikle de tedavi hacminin büyük olduğu tümörlerde istenen kriterlere ulaşılamadığı gösterilmiştir.

Keywords

• Larinks Kanseri
• Radyoterapi
• IMAT
• CyberKnife
• Dozimetri

Treatment Planning Comparison of Intensity Modulated Arc Therapy and CyberKnife Techniques in Early Stage Glottic Larynx Radiotherapy

Abstract

We aimed to compare two radiotherapy techniques (the robotic-based linear accelerator Stereotactic Body Radiotherapy (SBRT) and linear accelerator-based Intensity Modulated Arc Therapy (IMAT)) dosimetrically on Early Glottic Larynx Cancerx (EGL) treatment plans in the terms of target volume and critical organ doses. The computerized tomography (CT) images of 15 patients treated with EGL diagnosis were used retrospectively. The Planning Target Volumes (PTV) was generated with a margin of 0.5 cm from the laryngeal volume. The PTV dose was defined as 45 Gy delivered in 10 fractions within each of treatment plans. At least 95% of PTV treatment volumes (D95%) were to receive the treatment dose. The average PTV volume was 95.56 cm3 (range: 68.8 cm3 - 142.6 cm3). The average D98%, D2% and Dmean values of PTV were lower in IMAT plan than in CK plan. In CK plans, the mean of the spinal cord maximum dose (Dmax) for all patients was statistically significantly lower than in IMAT plans. Dmax and Dmean values for the right and left carotid arteries was significantly lower in IMAT plans. Also, the Dmean value of thyroid gland was significantly lower in IMAT plans. Our dosimetric comparison study made using images of 15 EGL cancer patients shows that the desired critria for the critical organ doses can not reached with CK plans, especially when the treatment volume is large.

Keywords

• Larenks Cancer
• Radiotherapy
• IMAT
• CyberKnife
• Dozimetry

References

1. [1] J. Ferlay, I. Soerjomataram, R. Dikshit, S. Eser, C. Mathers, and M. Rebelo, “Cancer incidence and mortality worldwide: Sources, methods and major patterns in GLOBOCAN 2012,” Int. J. Cancer, 136 (5), 359–86, 2015.
2. [2] R. L. Siegel, K. D. Miller, and A. Jemal, “Cancer statistics, 2018.” CA: A Cancer J. Clin., 68 (1), 7–30, 2018.
3. [3] W. M. Mendenhall, R. J. Amdur, C. G. Morris, et al. “T1-T2N0 squamous cell carcinoma of the glottic larynx treated with radiation therapy,” J. Clin. Oncol., 19, 4029–4036, 2001.
4. [4] H. Yamazaki, K. Nishiyama, E. Tanaka, M. Ko izumi, and M. Chatani, “Radiotherapy for early glottic carcinoma (T1N0M0): results of prospective randomized study of radiation fraction size and overall treatment time,” Int. J. Radiat. Oncol. Biol. Phys., 64, 77–82, 2006.
5. [5] S. H. Moon, K. H. Cho, E. J. Chung et al. “A prospective randomized trial comparing hypofractionation with conventional fractionation radiotherapy for T1-2 glottic squamous cell carcinomas: results of a Korean radiation oncology group (KROG-0201) study,” Radiat Oncol., 110, 98–103, 2014.
6. [6] ICRU Report 83. “Prescribing, Recording and Reporting Photon-Beam Intensity Modulated Radiation Therapy (IMRT),” Journal of the ICRU, 1–35, 2010.
7. [7] W. Mao, T. Rozario, W. Lu, X. Gu, Y. Yan, X. Jia, et al. “Online dosimetric evaluation of larynx SBRT: A pilot study to assess the necessity of adaptive replanning,” J Appl Clin Med Phys., 18, 157– 63, 2017.
8. [8] M. Rubinstein and W. B. Armstrong. “Transoral laser microsurgery for laryngeal cancer: A primer and review of laser dosimetry,” Lasers Med. Sci., 26 (1), 113–24, 2011.

9. [9] D. L. Schwartz, A. Sosa, S. G. Chun, C. Ding, X-J. Xie, L.A. Nedzi, et al. “SBRT for early-stage glottic larynx cancer-Initial clinical outcomes from a phase I clinical trial,” PLoS One., 2, 12 (3), (e0172055), 1-10, 2017.
10. [10] C. Ding, S. G. Chun, B. D. Sumer, L. A. Nedzi, R. E. Abdulrahman, J. S. Yordy, et al. “Phantom-to-clinic development of hypofractionated stereotactic body radiotherapy for early-stage glottic laryngeal cancer,” Med Dosim., 42 (2), 90–6. 2017.
11. [11] Y. Zhang, T. Chiu, J. Dubas, Z. Tian, P. Lee et al. “Benchmarking techniques for stereotactic body radiotherapy for early-stage glottic laryngeal cancer: LINAC-based noncoplanar VMAT vs. Cyberknife planning,” Radiat. Oncol., 14 (1), 193, 2019.
12. [12] A. C. Mueller and S. D. Karam, “SBRT for early stage larynx a go or no go? It's all in the delivery,” Int. J. Radiot. Oncol. Biol. Phys., 105 (1), 119–120, 2019.