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Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT.

Publication ,  Journal Article
Tian, Y; Wang, Z; Ge, H; Zhang, T; Cai, J; Kelsey, C; Yoo, D; Yin, F-F
Published in: Med Phys
May 2012

PURPOSE: To determine whether there is a CT dataset may be more favorable for planning and dose calculation by comparing dosimetric characteristics between treatment plans calculated using free breathing (FB), maximum and average intensity projection (MIP and AIP, respectively) CTs for lung cancer patients receiving stereotactic body radiation therapy (SBRT). METHODS: Twenty lung cancer SBRT patients, treated on a linac with 2.5 mm width multileaf-collimator (MLC), were analyzed retrospectively. Both FB helical and four-dimensional CT scans were acquired for each patient. Internal target volume (ITV) was delineated based on MIP CTs and modified based on both ten-phase datasets and FB CTs. Planning target volume (PTV) was then determined by adding additional setup margin to ITV. The PTVs and beams in the optimized treatment plan based on FB CTs were copied to MIP and AIP CTs, with the same isocenters, MLC patterns and monitor units. Mean effective depth (MED) of beams, and some dosimetric parameters for both PTVs and most important organ at risk (OAR), lung minus PTV, were compared between any two datasets using two-tail paired t test. RESULTS: The MEDs in FB and AIP plans were similar but significantly smaller (Ps < 0.001) than that in MIP plans. Minimum dose, mean dose, dose covering at least 90% and 95% of PTVs in MIP plans were slightly higher than two other plans (Ps < 0.008). The absolute volume of lung minus PTV receiving greater than 5, 10, and 20 Gy in MIP plans were significantly smaller than those in both FB and AIP plans (Ps < 0.008). Conformity index for FB plans showed a small but statistically significantly higher. CONCLUSIONS: Dosimetric characteristics of AIP plans are similar to those of FB plans. Slightly better target volume coverage and significantly lower low-dose region (≤30 Gy) in lung was observed in MIP plans. The decrease in low-dose region in lung was mainly caused by the change of lung volume contoured on two datasets rather than the differences of dose distribution between AIP and MIP plans. Compare with AIP datasets, FB datasets were more prone to significant image artifacts and MIP datasets may overestimate or underestimate the target volume when the target is closer to the denser tissue, so AIP seems favorable for planning and dose calculation for lung SBRT.

Duke Scholars

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

May 2012

Volume

39

Issue

5

Start / End Page

2754 / 2760

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Respiration
  • Radiotherapy Planning, Computer-Assisted
  • Radiosurgery
  • Radiometry
  • Nuclear Medicine & Medical Imaging
  • Lung Neoplasms
  • Humans
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Tian, Y., Wang, Z., Ge, H., Zhang, T., Cai, J., Kelsey, C., … Yin, F.-F. (2012). Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT. Med Phys, 39(5), 2754–2760. https://doi.org/10.1118/1.4705353
Tian, Yuan, Zhiheng Wang, Hong Ge, Tian Zhang, Jing Cai, Christopher Kelsey, David Yoo, and Fang-Fang Yin. “Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT.Med Phys 39, no. 5 (May 2012): 2754–60. https://doi.org/10.1118/1.4705353.
Tian Y, Wang Z, Ge H, Zhang T, Cai J, Kelsey C, et al. Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT. Med Phys. 2012 May;39(5):2754–60.
Tian, Yuan, et al. “Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT.Med Phys, vol. 39, no. 5, May 2012, pp. 2754–60. Pubmed, doi:10.1118/1.4705353.
Tian Y, Wang Z, Ge H, Zhang T, Cai J, Kelsey C, Yoo D, Yin F-F. Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT. Med Phys. 2012 May;39(5):2754–2760.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

May 2012

Volume

39

Issue

5

Start / End Page

2754 / 2760

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Respiration
  • Radiotherapy Planning, Computer-Assisted
  • Radiosurgery
  • Radiometry
  • Nuclear Medicine & Medical Imaging
  • Lung Neoplasms
  • Humans
  • 5105 Medical and biological physics
  • 4003 Biomedical engineering