• Title/Summary/Keyword: 매트릭스형 팬톰

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The Influence of Volume Effect in 2D-array Ion Chamber on the Measurement of IMRT Dose Distribution (2차원 배열형 이온함의 부피효과가 세기조절방사선치료의 선량분포 측정에 미치는 영향)

  • Kim, Sung Joon;Lee, Seoung Jun;Park, In Kyu;Lee, Jeong Eun;Park, Shin Hyung;Seol, Ki Ho;Kim, Jae Chul
    • Progress in Medical Physics
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    • v.24 no.1
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    • pp.41-47
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    • 2013
  • We evaluated the influence of volume effect on the measurement of IMRT dose distribution by comparing a 2D-array ion chamber and other dosimeters. Matrix phantom which is a 2D-array ion chamber having volume effect was compared with beam image system and film for the measurement of dose distribution. Five intensity-modulated radiation therapy plans were created using five fields in thevirtual phantom. The measured dose distribution was compared with the calculated one by radiation treatment planning system and analysis program. We evaluated the conformity of dose distribution by calculating correlation coefficients and gamma values. The highest error rate of 1.3% was associated with matrix phantom in which volume effect in small field sizes was substantial.

IMRT and IMRS Checking the Dose Distribution in the Small Field Evaluation of Measurement by Changes in SAD (IMRT 및 IMRS에서 Small Field의 선량분포 확인시 SAD 변화에 따른 측정의 유용성 평가)

  • Ko, Seung-Young;Kim, Sung-Joon;Park, Gir-Yong;Son, Mi-Suk;Lee, Nam-Ki;Kim, Jin-Soo
    • The Journal of Korean Society for Radiation Therapy
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    • v.22 no.1
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    • pp.33-39
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    • 2010
  • Purpose: It is very important to confirm conformance of dose distribution that is formed with treatment planning from IMRS or IMRT. It has been a problem dropped accuracy and conformance when the field size is getting smaller because of character of the 2D ion chamber. Verification of MatriXX Phantom dose distribution with a change in the SAD. Dose distribution measurement and analysis to improve the accuracy and should be useful to evaluate the award. Materials and Methods: A use of Novalis linear accelerator 6 MV photon beams. In general, IMRS were 25 patients with small field size. The selected patients were divided into three groups on the basis of the field size. SAD was changed from 80 to 130 cm and field size to determine the dose distribution to the change, each dose was measured using MatriXX Phantom. Analysis of measured values obtained from the program for each patient through the treatment planning system comparison and analysis of the dose distribution and gamma values were expressed. Result: SAD 80, 100, and 120 cm in size in the gamma value to the investigation of patients less than $3\;cm^2$ average 0.939, 0.969, and 0.979, respectively. Patients with more than $5\;cm^2$ 0.962, 0.983, and 0.988, respectively. $5\;cm^2$ or more patients 0.982, 0.990, and 0.992, respectively. Conclusion: The error rate of less than $3\;cm^2$ field size is increased rapidly. If the field size is increased, resolution is increased by 2D ion chambers. It has been approved that it can be credible if it is around $3\;cm^2$ when measuring dose distribution using MatriXX. Adjusting geometric field size by changing SAD is likely to be very useful when you measure dose distribution using MatriXX.

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