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Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor.

Publication ,  Journal Article
Xin-Ye, N; Ren, L; Yan, H; Yin, F-F
Published in: Technol Cancer Res Treat
December 2016

PURPOSE: This study aimed to detect the sensitivity of Delt 4 on ordinary field multileaf collimator misalignments, system misalignments, random misalignments, and misalignments caused by gravity of the multileaf collimator in stereotactic body radiation therapy. METHODS: (1) Two field sizes, including 2.00 cm (X) × 6.00 cm (Y) and 7.00 cm (X) × 6.00 cm (Y), were set. The leaves of X1 and X2 in the multileaf collimator were simultaneously opened. (2) Three cases of stereotactic body radiation therapy of spinal tumor were used. The dose of the planning target volume was 1800 cGy with 3 fractions. The 4 types to be simulated included (1) the leaves of X1 and X2 in the multileaf collimator were simultaneously opened, (2) only X1 of the multileaf collimator and the unilateral leaf were opened, (3) the leaves of X1 and X2 in the multileaf collimator were randomly opened, and (4) gravity effect was simulated. The leaves of X1 and X2 in the multileaf collimator shifted to the same direction. The difference between the corresponding 3-dimensional dose distribution measured by Delt 4 and the dose distribution in the original plan made in the treatment planning system was analyzed with γ index criteria of 3.0 mm/3.0%, 2.5 mm/2.5%, 2.0 mm/2.0%, 2.5 mm/1.5%, and 1.0 mm/1.0%. RESULTS: (1) In the field size of 2.00 cm (X) × 6.00 cm (Y), the γ pass rate of the original was 100% with 2.5 mm/2.5% as the statistical standard. The pass rate decreased to 95.9% and 89.4% when the X1 and X2 directions of the multileaf collimator were opened within 0.3 and 0.5 mm, respectively. In the field size of 7.00 (X) cm × 6.00 (Y) cm with 1.5 mm/1.5% as the statistical standard, the pass rate of the original was 96.5%. After X1 and X2 of the multileaf collimator were opened within 0.3 mm, the pass rate decreased to lower than 95%. The pass rate was higher than 90% within the 3 mm opening. (2) For spinal tumor, the change in the planning target volume V18 under various modes calculated using treatment planning system was within 1%. However, the maximum dose deviation of the spinal cord was high. In the spinal cord with a gravity of -0.25 mm, the maximum dose deviation minimally changed and increased by 6.8% than that of the original. In the largest opening of 1.00 mm, the deviation increased by 47.7% than that of the original. Moreover, the pass rate of the original determined through Delt 4 was 100% with 3 mm/3% as the statistical standard. The pass rate was 97.5% in the 0.25 mm opening and higher than 95% in the 0.5 mm opening A, 0.25 mm opening A, whole gravity series, and 0.20 mm random opening. Moreover, the pass rate was higher than 90% with 2.0 mm/2.0% as the statistical standard in the original and in the 0.25 mm gravity. The difference in the pass rates was not statistically significant among the -0.25 mm gravity, 0.25 mm opening A, 0.20 mm random opening, and original as calculated using SPSS 11.0 software with P > .05. CONCLUSIONS: Different analysis standards of Delt 4 were analyzed in different field sizes to improve the detection sensitivity of the multileaf collimator position on the basis of 90% throughout rate. In stereotactic body radiation therapy of spinal tumor, the 2.0 mm/2.0% standard can reveal the dosimetric differences caused by the minor multileaf collimator position compared with the 3.0 mm/3.0% statistical standard. However, some position derivations of the misalignments that caused high dose amount to the spinal cord cannot be detected. However, some misalignments were not detected when a large number of multileaf collimator were administered into the spinal cord.

Duke Scholars

Published In

Technol Cancer Res Treat

DOI

EISSN

1533-0338

Publication Date

December 2016

Volume

15

Issue

6

Start / End Page

NP25 / NP34

Location

United States

Related Subject Headings

  • Spinal Cord Neoplasms
  • Software
  • Sensitivity and Specificity
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy Dosage
  • Radiosurgery
  • Radiometry
  • Oncology & Carcinogenesis
  • Humans
  • 3211 Oncology and carcinogenesis
 

Citation

APA
Chicago
ICMJE
MLA
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Xin-Ye, N., Ren, L., Yan, H., & Yin, F.-F. (2016). Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor. Technol Cancer Res Treat, 15(6), NP25–NP34. https://doi.org/10.1177/1533034615610251
Xin-Ye, Ni, Lei Ren, Hui Yan, and Fang-Fang Yin. “Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor.Technol Cancer Res Treat 15, no. 6 (December 2016): NP25–34. https://doi.org/10.1177/1533034615610251.
Xin-Ye, Ni, et al. “Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor.Technol Cancer Res Treat, vol. 15, no. 6, Dec. 2016, pp. NP25–34. Pubmed, doi:10.1177/1533034615610251.
Xin-Ye N, Ren L, Yan H, Yin F-F. Sensitivity of 3D Dose Verification to Multileaf Collimator Misalignments in Stereotactic Body Radiation Therapy of Spinal Tumor. Technol Cancer Res Treat. 2016 Dec;15(6):NP25–NP34.
Journal cover image

Published In

Technol Cancer Res Treat

DOI

EISSN

1533-0338

Publication Date

December 2016

Volume

15

Issue

6

Start / End Page

NP25 / NP34

Location

United States

Related Subject Headings

  • Spinal Cord Neoplasms
  • Software
  • Sensitivity and Specificity
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy Dosage
  • Radiosurgery
  • Radiometry
  • Oncology & Carcinogenesis
  • Humans
  • 3211 Oncology and carcinogenesis