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[Dosimetric correction for a six degrees carbon fiber couch]
Yuji Nakaguchi1, Ryuji Murakami, Masato Maruyama
1Department of Radiological Technology, Kumamoto University Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi
|December 22, 2011
Summary
A six degree (6D) carbon fiber couch minimally impacts radiation therapy doses. Correction methods ensure precise treatment planning, though complex methods may not always be necessary, especially with multi-field irradiation.
Area of Science:
- Medical Physics
- Radiation Oncology
Background:
- Carbon fiber couches are used in radiation therapy to minimize image artifacts.
- The six degree (6D) couch offers advanced positioning capabilities but may affect dose distribution.
Purpose of the Study:
- To investigate the dosimetric influence of a 6D carbon fiber couch in conventional radiation therapy.
- To evaluate the effectiveness of different correction methods for 6D couch use.
- To assess the clinical relevance of these corrections in patient treatments.
Main Methods:
- Experimental phantom studies using 4, 6, and 10 MV X-rays.
- Comparison of dose distributions with and without the 6D couch, employing monitor unit (MU) addition, CT couch inclusion, and couch modeling correction techniques.
- Clinical evaluation in 30 patients undergoing multi-field irradiation.
Main Results:
- Phantom studies showed a maximum isocenter dose difference of 5.1% due to the 6D couch, decreasing with higher X-ray energy.
- Correction methods achieved isocenter dose precision within ±1%, but MU addition underestimated surface dose.
- Clinical studies revealed a maximum isocenter dose difference of 2.7% attributable to the 6D couch.
Conclusions:
- Correction methods enable highly precise treatment planning when using a 6D couch.
- The clinical necessity of complex correction methods should be individualized based on institutional protocols and patient-specific factors.
- The dosimetric impact of the 6D couch is diminished in multi-field irradiation techniques.
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