Comparison of 3D anatomical dose verification and 2D phantom dose verification of IMRT/VMAT treatments for nasopharyngeal carcinoma

Radiation Oncology

Lixin Chen²  Jinhan Zhu³  Xiaowu Deng²  Shaomin Huang²  Hailei Lin¹ 

[1] Department of Radiation Oncology, Beijing Hospital of the Ministry of Health, Beijing 100730, China;Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China;School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China

关键词: Dosimetry verification;    2D phantom dose;    3D anatomical dose;    VMAT;    IMRT;   

Others  :  1228552
DOI  :  10.1186/1748-717X-9-71

 received in 2013-12-16, accepted in 2014-03-02,  发布年份 2014

【 摘 要 】

Background

The two-dimensional phantom dose verification (2D-PDV) using hybrid plan and planar dose measurement has been widely used for IMRT treatment QA. Due to the lack of information about the correlations between the verification results and the anatomical structure of patients, it is inadequate in clinical evaluation. A three-dimensional anatomical dose verification (3D-ADV) method was used in this study to evaluate the IMRT/VMAT treatment delivery for nasopharyngeal carcinoma and comparison with 2D-PDV was analyzed.

Methods

Twenty nasopharyngeal carcinoma (NPC) patients treated with IMRT/VMAT were recruited in the study. A 2D ion-chamber array was used for the 2D-PDV in both single-gantry-angle composite (SGAC) and multi-gantry-angle composite (MGAC) verifications. Differences in the gamma pass rate between the 2 verification methods were assessed. Based on measurement of irradiation dose fluence, the 3D dose distribution was reconstructed for 3D-ADV in the above cases. The reconstructed dose homogeneity index (HI), conformity index (CI) of the planning target volume (PTV) were calculated. Gamma pass rate and deviations in the dose-volume histogram (DVH) of each PTV and organ at risk (OAR) were analyzed.

Results

In 2D-PDV, the gamma pass rate (3%, 3 mm) of SGAC (99.55% ± 0.83%) was significantly higher than that of MGAC (92.41% ± 7.19%). In 3D-ADV, the gamma pass rates (3%, 3 mm) were 99.75% ± 0.21% in global, 83.82% ± 16.98% to 93.71% ± 6.22% in the PTVs and 45.12% ± 32.78% to 98.08% ± 2.29% in the OARs. The maximum HI increment in PTVnx was 19.34%, while the maximum CI decrement in PTV1 and PTV2 were -32.45% and -6.93%, respectively. Deviations in dose volume of PTVs were all within ±5%. D2% of the brainstem, spinal cord, left/right optic nerves, and the mean doses to the left/right parotid glands maximally increased by 3.5%, 6.03%, 31.13%/26.90% and 4.78%/4.54%, respectively.

Conclusion

The 2D-PDV and global gamma pass rate might be insufficient to provide an accurate assessment for the complex NPC IMRT operation. In contrast, the 3D-ADV is superior in clinic-related quality assurance offering evaluation of organ specific pass rate and dose-volume deviations.

【 授权许可】

   
2014 Lin et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

【 参考文献 】

• [1]Hendee WR, Herman MG: Improving patient safety in radiation oncology. Med Phys 2011, 38(1):78-82.
• [2]Low DA, Moran JM, Dempsey JF, Dong L, Oldham M: Dosimetry tools and techniques for IMRT. Med Phys 2011, 38(3):1313-1338.
• [3]Nelms BE, Zhen HM, Tome WA: Per-beam planar IMRT QA passing rates do not predict clinically relevant patient dose errors. Med Phys 2011, 38(2):1037-1043.
• [4]Boggula R, Jahnke L, Wertz H, Lohr F, Wenz F: Patient-specific 3D pretreatment and potential 3D online dose verification of Monte Carlo-calculated IMRT prostate treatment plans. Int J Radiat Oncol Biol Phys 2011, 81(4):1168-1175.
• [5]McCurdy , Mueller L, Backman E, Venkataraman S, Fleming E, Asuni G, Jensen M, Ur-Rehman F, Pistorius S: Commissioning and validation of a novel measurement-based IMRT QA method, incorporating dose recalculation on patient CT data. Med Phys 2008, 35(6):2760-2760.
• [6]Godart J, Korevaar EW, Visser R, Wauben DJL, Van't Veld AA: Reconstruction of high-resolution 3D dose from matrix measurements: error detection capability of the COMPASS correction kernel method. Phys Med Biol 2011, 56(15):5029-5043.
• [7]Lin HL, Huang SM, Deng XW, Jin GH, Sun WZ, Yao XH, Zhang DD, Chen LX: A clinical test and application research of IMRT dose verification system based on patient's anatomical structure and on-line dosimetry. Chin J Radiat Oncol 2012, 21(3):271-275.
• [8]Nelms BE, Simon JA: A survey of planar IMRT QA analysis. J Appl Clin Med Phys 2007, 8(3):1-15.
• [9]Shimohigashi Y, Araki F, Tominaga H, Sakata J, Kawasaki K, Kanetake N, Iwashita Y, Yoshimura S, Kawakami T, Ishihara T, Okuda T, Kogo K: Angular dependence correction of MatriXX and its application to composite dose verification. J Appl Clin Med Phys 2012, 13(5):198-214.
• [10]Low DA, Harms WB, Mutic S, Purdy JA: A technique for the quantitative evaluation of dose distributions. Med Phys 1998, 25(5):656-661.
• [11]Boggula R, Lorenz F, Mueller L, Birkner M, Wertz H, Stieler F, Steil V, Lohr F, Wenz F: Experimental validation of a commercial 3D dose verification system for intensity-modulated arc therapies. Phys Med Biol 2010, 55(19):5619-5633.
• [12]Feuvret L, Noël G, Mazeron JJ, Bey P: Conformity index: a review. Int J Radiat Oncol Biol Phys 2006, 64(2):333-342.
• [13]ICRU report 83: Prescribing, recording, and reporting intensity-modulated photon-beam therapy. J ICRU 2010, 10(1):1-106.
• [14]Wolfsberger L, Wagar M, Nitsch P, Bhagwat M, Zygmanski P: Angular dose dependency of matrixx TM and its calibration. J Appl Clin Med Phys 2010, 11(1):241-251.
• [15]Lee TF, Chao PJ, Ting HM: Comparative analysis of SmartArc-based dual arc volumetric-modulated arc radiotherapy (VMAT) versus intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma. J Appl Clin Med Phy 2011, 12(4):158-174.
• [16]Li QL, Deng XW, Chen LX, Huang XY, Huang SM: The angular dependence of a 2-dimensional diode array and the feasibility of its application in verifying the composite dose distribution of intensity-modulated radiation therapy. Chin J Canc 2010, 29(6):617-620.
• [17]Elmpt WV, Nijsten S, Mijnheer B, Dekker A, Lambin P: The next step in patient-specific QA: 3D dose verification of conformal and intensity-modulated RT based on EPID dosimetry and Monte Carlo dose calculations. Radiother Oncol 2008, 86(1):86-92.
• [18]Stasi M, Bresciani S, Miranti A, Maggio A, Sapino V, Gabriele P: Pretreatment patient-specific IMRT quality assurance: a correlation study between gamma index and patient clinical dose volume histogram. Med Phys 2012, 39(12):7626-7634.
• [19]Carrasco P, Jornet N, Latorre A, Eudaldo T, Ruiz A, Ribas M: 3D DVH-based metric analysis versus per-beam planar analysis in IMRT pretreatment verification. Med Phys 2012, 39(8):5040-5049.