Dosimetric investigation of breath-hold intensity-modulated radiotherapy for pancreatic cancer

Mitsuhiro Nakamura, Shun Kishimoto, Kohei Iwamura, Takehiro Shiinoki, Akira Nakamura, Yukinori Matsuo, Keiko Shibuya, Masahiro Hiraoka

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Purpose: To experimentally investigate the effects of variations in respiratory motion during breath-holding (BH) at end-exhalation (EE) on intensity-modulated radiotherapy (BH-IMRT) dose distribution using a motor-driven base, films, and an ionization chamber. Methods: Measurements were performed on a linear accelerator, which has a 120-leaf independently moving multileaf collimator with 5-mm leaf width at the isocenter for the 20-cm central field. Polystyrene phantoms with dimensions of 40 × 40 × 10 cm were set on a motor-driven base. All gantry angles of seven IMRT plans (a total of 35 fields) were changed to zero, and doses were then delivered to a film placed at a depth of 4 cm and an ionization chamber at a depth of 5 cm in the phantom with a dose rate of 600 MU/min under the following conditions: pulsation from the abdominal aorta and baseline drift with speeds of 0.2 mm/s (BD 0.2mm/s) and 0.4 mm/s (BD0.4mm/s). As a reference for comparison, doses were also delivered to the chamber and film under stationary conditions. Results: In chamber measurements, means ± standard deviations of the dose deviations between stationary and moving conditions were -0.52% ± 1.03% (range: -3.41-1.05%), -0.07% ± 1.21% (range: -1.88-4.31%), and 0.03% ± 1.70% (range: -2.70-6.41%) for pulsation, BD 0.2mm/s, and BD0.4mm/s, respectively. The γ passing rate ranged from 99.5% to 100.0%, even with the criterion of 2%/1 mm for pulsation pattern. In the case of BD0.4mm/s, the γ passing rate for four of 35 fields (11.4) did not reach 90 with a criterion of 3/3 mm. The differences in γ passing rate between BD0.2mm/s and BD 0.4mm/s were statistically significant for each criterion. Taking γ passing rates of >90% as acceptable with a criterion of >3%/3 mm, large differences were observed in the γ passing rate between the baseline drift of ≤5 mm and that of >5 mm (minimum passing rate: 92.0% vs 82.7%; p < 0.01). Conclusions: This study suggested that the baseline drift of >5 mm should be avoided in the BH-IMRT.

Original languageEnglish (US)
Pages (from-to)48-54
Number of pages7
JournalMedical physics
Volume39
Issue number1
DOIs
StatePublished - Jan 1 2012

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Breath Holding
Intensity-Modulated Radiotherapy
Pancreatic Neoplasms
Exhalation
Particle Accelerators
Polystyrenes
Abdominal Aorta

Keywords

  • breath-holding
  • dosimetry
  • intensity-modulated radiotherapy
  • interplay effect
  • pancreatic cancer

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

Nakamura, M., Kishimoto, S., Iwamura, K., Shiinoki, T., Nakamura, A., Matsuo, Y., ... Hiraoka, M. (2012). Dosimetric investigation of breath-hold intensity-modulated radiotherapy for pancreatic cancer. Medical physics, 39(1), 48-54. https://doi.org/10.1118/1.3668314

Dosimetric investigation of breath-hold intensity-modulated radiotherapy for pancreatic cancer. / Nakamura, Mitsuhiro; Kishimoto, Shun; Iwamura, Kohei; Shiinoki, Takehiro; Nakamura, Akira; Matsuo, Yukinori; Shibuya, Keiko; Hiraoka, Masahiro.

In: Medical physics, Vol. 39, No. 1, 01.01.2012, p. 48-54.

Research output: Contribution to journalArticle

Nakamura, M, Kishimoto, S, Iwamura, K, Shiinoki, T, Nakamura, A, Matsuo, Y, Shibuya, K & Hiraoka, M 2012, 'Dosimetric investigation of breath-hold intensity-modulated radiotherapy for pancreatic cancer', Medical physics, vol. 39, no. 1, pp. 48-54. https://doi.org/10.1118/1.3668314
Nakamura M, Kishimoto S, Iwamura K, Shiinoki T, Nakamura A, Matsuo Y et al. Dosimetric investigation of breath-hold intensity-modulated radiotherapy for pancreatic cancer. Medical physics. 2012 Jan 1;39(1):48-54. https://doi.org/10.1118/1.3668314
Nakamura, Mitsuhiro ; Kishimoto, Shun ; Iwamura, Kohei ; Shiinoki, Takehiro ; Nakamura, Akira ; Matsuo, Yukinori ; Shibuya, Keiko ; Hiraoka, Masahiro. / Dosimetric investigation of breath-hold intensity-modulated radiotherapy for pancreatic cancer. In: Medical physics. 2012 ; Vol. 39, No. 1. pp. 48-54.
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AU - Nakamura, Akira

AU - Matsuo, Yukinori

AU - Shibuya, Keiko

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N2 - Purpose: To experimentally investigate the effects of variations in respiratory motion during breath-holding (BH) at end-exhalation (EE) on intensity-modulated radiotherapy (BH-IMRT) dose distribution using a motor-driven base, films, and an ionization chamber. Methods: Measurements were performed on a linear accelerator, which has a 120-leaf independently moving multileaf collimator with 5-mm leaf width at the isocenter for the 20-cm central field. Polystyrene phantoms with dimensions of 40 × 40 × 10 cm were set on a motor-driven base. All gantry angles of seven IMRT plans (a total of 35 fields) were changed to zero, and doses were then delivered to a film placed at a depth of 4 cm and an ionization chamber at a depth of 5 cm in the phantom with a dose rate of 600 MU/min under the following conditions: pulsation from the abdominal aorta and baseline drift with speeds of 0.2 mm/s (BD 0.2mm/s) and 0.4 mm/s (BD0.4mm/s). As a reference for comparison, doses were also delivered to the chamber and film under stationary conditions. Results: In chamber measurements, means ± standard deviations of the dose deviations between stationary and moving conditions were -0.52% ± 1.03% (range: -3.41-1.05%), -0.07% ± 1.21% (range: -1.88-4.31%), and 0.03% ± 1.70% (range: -2.70-6.41%) for pulsation, BD 0.2mm/s, and BD0.4mm/s, respectively. The γ passing rate ranged from 99.5% to 100.0%, even with the criterion of 2%/1 mm for pulsation pattern. In the case of BD0.4mm/s, the γ passing rate for four of 35 fields (11.4) did not reach 90 with a criterion of 3/3 mm. The differences in γ passing rate between BD0.2mm/s and BD 0.4mm/s were statistically significant for each criterion. Taking γ passing rates of >90% as acceptable with a criterion of >3%/3 mm, large differences were observed in the γ passing rate between the baseline drift of ≤5 mm and that of >5 mm (minimum passing rate: 92.0% vs 82.7%; p < 0.01). Conclusions: This study suggested that the baseline drift of >5 mm should be avoided in the BH-IMRT.

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