WO2011093183A1 - Method of measuring two-dimensional distribution of radiological dose using 3d phantom - Google Patents

Method of measuring two-dimensional distribution of radiological dose using 3d phantom Download PDF

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WO2011093183A1
WO2011093183A1 PCT/JP2011/050841 JP2011050841W WO2011093183A1 WO 2011093183 A1 WO2011093183 A1 WO 2011093183A1 JP 2011050841 W JP2011050841 W JP 2011050841W WO 2011093183 A1 WO2011093183 A1 WO 2011093183A1
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phantom
dose
measuring
radiation
distribution
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修一 小澤
智久 古谷
基敬 川嶋
千恵 黒河
久美子 唐澤
啓資 笹井
宏 大西
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学校法人順天堂
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/169—Exploration, location of contaminated surface areas

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  • the present invention relates to a method for measuring a two-dimensional distribution of radiation absorbed dose using a 3D phantom implemented in the field of radiotherapy.
  • the absorbed dose using a 3D phantom (three-dimensional model) is used to verify whether the results obtained in the treatment plan are correct. Compare the measured and calculated two-dimensional distributions.
  • the coronal plane and the sagittal plane are measured and compared with the calculation results.
  • a radiation dose measuring body 20 such as an X-ray film is sandwiched between the stacked 3D phantoms 50 and irradiated, and then FIG. As shown in 2), the 3D phantom 50 sandwiching the radiation dose measuring body 20 is rotated by 90 ° to perform irradiation, and the dose distribution on the sagittal surface is measured (for example, see Non-Patent Document 1).
  • the close contact between the 3D phantom 50 and the radiation dose measuring body 20 is increased by the dead weight of the 3D phantom 50, and it takes less time for installation, so that the measurement accuracy is high and the reproducibility of the measurement is also high.
  • the degree of adhesion cannot be increased due to the weight of the 3D phantom 50, which causes a problem that the measurement accuracy is lowered and the reproducibility is deteriorated.
  • the 3D phantom 50 is sandwiched with a clamp 60 or the like to increase the degree of adhesion.
  • the present invention has been made in view of the above-described conventional problems and actual situations, and can perform two-dimensional distribution measurement of a radiation absorbed dose using a 3D phantom efficiently and accurately with high reproducibility.
  • the challenge is to provide a method that can do this.
  • the present inventor conducted a 3D phantom having a 90 ° rotationally symmetric sectional shape instead of rotating the 3D phantom by 90 ° for dose distribution measurement on the sagittal surface. If the gantry of the radiation therapy device is rotated 90 ° and irradiated with radiation, the measurement accuracy on the sagittal surface will be as high as that on the coronal surface, and results with good reproducibility will be obtained. As a result, the present invention has been completed.
  • the present invention includes a step of holding a radiation dose measuring body in a horizontal state between a 3D phantom composed of two upper and lower divided bodies having a 90 ° rotationally symmetric sectional shape; and holding the radiation dose measuring body in a horizontal state.
  • the radiation dose measuring body in measuring not only the coronal plane but also the sagittal plane, the radiation dose measuring body is held horizontally between the 3D phantoms. Therefore, the degree of adhesion with the radiation dose measuring body by the weight of the 3D phantom. Therefore, the two-dimensional distribution of radiation dose can be measured with high accuracy.
  • the rotation of the gantry can be easily operated by the controller of the radiotherapy device (linac), it is possible to perform measurement more efficiently and with higher reproducibility than the conventional rotation operation of the 3D phantom by a clamp or the like.
  • 10 is a 3D phantom, which is composed of two divided parts of an upper phantom part 10a and a lower phantom part 10b, and becomes symmetric when rotated by 90 °, such as a square or an octagon. It has a cross-sectional shape.
  • the radiation dose measuring body 20 is set up between the upper phantom portion 10a and the lower phantom portion 10b of the 3D phantom 10, and the radiation dose measuring body 20 is held in a horizontal state.
  • the radiation dose measuring body 20 may be any type as long as it can measure the radiation dose.
  • an X-ray film, an imaging plate, a two-dimensional diode detector, a two-dimensional ionization chamber. A detector or the like is used.
  • the dose distribution on the coronal surface is measured by irradiating the 3D phantom 10 holding the radiation dose measuring body 20 in a horizontal state with the gantry 30a, 30b, 30c, 30d, 30e of the radiotherapy device (linac). (See FIG. 1 (1)).
  • the controller (not shown) rotates the gantry 30a, 30b, 30c, 30d, 30e by 90 °, and in that state, the 3D phantom 10 is irradiated with radiation to irradiate the sagittal surface.
  • the dose distribution is measured (see FIG. 1 (2)). Note that the 90 ° rotation direction may be clockwise or counterclockwise, and the position where the film is sandwiched may not be the center of the phantom.
  • the actual measurement value obtained is verified by comparing with the calculated value on the coronal surface and sagittal surface obtained by the same procedure as the normal method, whether the result obtained in the treatment plan is correct. .
  • 3D phantom 10a Upper phantom part 10b: Lower phantom part 20: Radiation dose measuring body 30a, 30b, 30c, 30d, 30e: Gantry 50: Conventional 3D phantom 60: Clamp

Abstract

Disclosed is a method of efficiently and accurately measuring the two-dimensional distribution of radiological dose using a 3D phantom with high reproducibility. The method comprises a step of holding a radiation-dose measuring body such that the measuring body is in a horizontal position between the 3D phantom that are formed of upper and lower separable bodies and of which cross-sectional shapes are symmetric with respect to 90°; a step of measuring a dose distribution in the coronal plane by emitting radial rays onto the 3D phantom that holds the radiation-dose measuring body in a horizontal position using gantries of a radiotherapy device; and a step of measuring a dose distribution in the sagittal plane by emitting radial rays onto the 3D phantom after the gantries are rotated by 90° without changing the position of the 3D phantom.

Description

３Ｄファントムを用いた放射線吸収線量の２次元分布測定方法Method for measuring two-dimensional distribution of absorbed radiation dose using a 3D phantom
　本発明は、放射線治療分野において実施される３Ｄファントムを用いた放射線吸収線量の２次元分布測定方法に関する。 The present invention relates to a method for measuring a two-dimensional distribution of radiation absorbed dose using a 3D phantom implemented in the field of radiotherapy.
　強度変調放射線治療（ＩＭＲＴ）や強度変調回転放射線治療（ＶＭＡＴ）などの高精度放射線治療では、治療計画で得られた結果が正しいのかを検証するため、３Ｄファントム（立体模型）を用いた吸収線量の２次元分布の実測と計算結果を比較する。通常、コロナル面とサジタル面の２面の測定を行い、計算結果と比較する。従来、コロナル面の測定では、第２図（１）に示すように、積み上げた３Ｄファントム５０の間にＸ線フィルム等の放射線量測定体２０を挟み、照射を行い、その後、第２図（２）に示すように、当該放射線量測定体２０を挟んだ３Ｄファントム５０を９０°回転させて、照射を行い、サジタル面の線量分布を測定していた（例えば、非特許文献１参照）。 In high-precision radiotherapy such as intensity-modulated radiotherapy (IMRT) and intensity-modulated rotational radiotherapy (VMAT), the absorbed dose using a 3D phantom (three-dimensional model) is used to verify whether the results obtained in the treatment plan are correct. Compare the measured and calculated two-dimensional distributions. Usually, the coronal plane and the sagittal plane are measured and compared with the calculation results. Conventionally, in the measurement of the coronal surface, as shown in FIG. 2 (1), a radiation dose measuring body 20 such as an X-ray film is sandwiched between the stacked 3D phantoms 50 and irradiated, and then FIG. As shown in 2), the 3D phantom 50 sandwiching the radiation dose measuring body 20 is rotated by 90 ° to perform irradiation, and the dose distribution on the sagittal surface is measured (for example, see Non-Patent Document 1).
　当該コロナル面の測定では、３Ｄファントム５０の自重によって３Ｄファントム５０と放射線量測定体２０の密着度が高くなり、設置の手間もかからないため、測定精度も高く、測定の再現性も高い。しかし、サジタル面での測定では３Ｄファントム５０の自重で密着度を上げることができなくなるため、測定精度の低下を生み、再現性を悪化させると云う問題があった。そのため、従来はクランプ６０等で３Ｄファントム５０を挟むなどして密着度を上げることも行われていたが、コロナル面での測定を比較して手間がかかり再現性悪化は避けられないのが実状であった。 In the measurement of the coronal surface, the close contact between the 3D phantom 50 and the radiation dose measuring body 20 is increased by the dead weight of the 3D phantom 50, and it takes less time for installation, so that the measurement accuracy is high and the reproducibility of the measurement is also high. However, in the measurement on the sagittal plane, the degree of adhesion cannot be increased due to the weight of the 3D phantom 50, which causes a problem that the measurement accuracy is lowered and the reproducibility is deteriorated. For this reason, conventionally, the 3D phantom 50 is sandwiched with a clamp 60 or the like to increase the degree of adhesion. However, it is troublesome to compare the measurements on the coronal surface, and deterioration of reproducibility is unavoidable. Met.
　本発明は、上記の如き従来の問題と実状に鑑みてなされたものであり、３Ｄファントムを用いた放射線吸収線量の２次元分布測定を、効率的にかつ精度良く、しかも再現性高く行なうことができる方法を提供することを課題としている。 The present invention has been made in view of the above-described conventional problems and actual situations, and can perform two-dimensional distribution measurement of a radiation absorbed dose using a 3D phantom efficiently and accurately with high reproducibility. The challenge is to provide a method that can do this.
　本発明者は、上記の課題を解決すべく、種々検討を重ねた結果、サジタル面の線量分布測定を、３Ｄファントムを９０°回転させるのではなく、９０°回転対称の断面形状を有する３Ｄファントムを用い、放射線治療装置のガントリを９０°回転させて放射線を照射すれば、サジタル面での測定においてもコロナル面での測定と同様に測定精度が高く、再現性の良い結果が得られることを見い出し、本発明を完成した。 As a result of various studies to solve the above-mentioned problems, the present inventor conducted a 3D phantom having a 90 ° rotationally symmetric sectional shape instead of rotating the 3D phantom by 90 ° for dose distribution measurement on the sagittal surface. If the gantry of the radiation therapy device is rotated 90 ° and irradiated with radiation, the measurement accuracy on the sagittal surface will be as high as that on the coronal surface, and results with good reproducibility will be obtained. As a result, the present invention has been completed.
　すなわち、本発明は、９０°回転対称の断面形状を有する上下２分割体から成る３Ｄファントムの間に、放射線量測定体を水平状態に挾持せしめるステップと；当該放射線量測定体を水平状態に挾持した３Ｄファントムに、放射線治療装置のガントリにて放射線を照射してコロナル面の線量分布を測定するステップと；当該３Ｄファントムの位置を変えることなく、ガントリを９０°回転させ、その状態で当該３Ｄファントムに放射線を照射してサジタル面の線量分布を測定するステップとを有することを特徴とする３Ｄファントムを用いた放射線吸収線量の２次元分布測定方法により上記課題を解決したものである。 That is, the present invention includes a step of holding a radiation dose measuring body in a horizontal state between a 3D phantom composed of two upper and lower divided bodies having a 90 ° rotationally symmetric sectional shape; and holding the radiation dose measuring body in a horizontal state. Irradiating the 3D phantom with radiation from the gantry of the radiotherapy device and measuring the dose distribution on the coronal surface; rotating the gantry by 90 ° without changing the position of the 3D phantom, and in that state the 3D The above-mentioned problem is solved by a method for measuring a two-dimensional distribution of radiation absorbed dose using a 3D phantom, characterized by comprising a step of irradiating a phantom with radiation and measuring a dose distribution on a sagittal surface.
　本発明によれば、コロナル面のみならずサジタル面の測定においても、放射線量測定体が３Ｄファントムの間に水平状態に挾持されているので、３Ｄファントムの自重で放射線量測定体との密着度を上げることができるため、精度良く放射線量の２次元分布を測定することが可能となる。 According to the present invention, in measuring not only the coronal plane but also the sagittal plane, the radiation dose measuring body is held horizontally between the 3D phantoms. Therefore, the degree of adhesion with the radiation dose measuring body by the weight of the 3D phantom. Therefore, the two-dimensional distribution of radiation dose can be measured with high accuracy.
　また、ガントリの回転は放射線治療装置（リニアック）のコントローラで容易に操作し得るので、従来のクランプ等による３Ｄファントムの回転操作に比し効率的に、しかも再現性の高い測定が可能となる。 Also, since the rotation of the gantry can be easily operated by the controller of the radiotherapy device (linac), it is possible to perform measurement more efficiently and with higher reproducibility than the conventional rotation operation of the 3D phantom by a clamp or the like.
本発明方法を示す概略模式説明図。The schematic model explanatory drawing which shows this invention method. 従来方法を示す概略模式説明図。Schematic explanatory drawing which shows a conventional method.
　以下本発明方法を図面と共に説明する。 Hereinafter, the method of the present invention will be described with reference to the drawings.
　図１において、１０は３Ｄファントムで、上部ファントム部１０ａと下部ファントム部１０ｂの２分割体から構成されていると共に、例えば正方形や八角形等のように、９０°回転させたときに対称となる断面形状を有している。 In FIG. 1, 10 is a 3D phantom, which is composed of two divided parts of an upper phantom part 10a and a lower phantom part 10b, and becomes symmetric when rotated by 90 °, such as a square or an octagon. It has a cross-sectional shape.
　本発明においては、まず斯かる３Ｄファントム１０の上部ファントム部１０ａと下部ファントム部１０ｂとの間に放射線量測定体２０をセットアップし、当該放射線量測定体２０を水平状態に挾持せしめる。尚、ここに放射線量測定体２０としては、放射線量を測定し得るものであれば、その種類の如何を問わないが、例えばＸ線フィルム，イメージングプレート，２次元ダイオード検出器，２次元電離箱検出器等が用いられる。 In the present invention, first, the radiation dose measuring body 20 is set up between the upper phantom portion 10a and the lower phantom portion 10b of the 3D phantom 10, and the radiation dose measuring body 20 is held in a horizontal state. Here, the radiation dose measuring body 20 may be any type as long as it can measure the radiation dose. For example, an X-ray film, an imaging plate, a two-dimensional diode detector, a two-dimensional ionization chamber. A detector or the like is used.
　次いで、当該放射線量測定体２０を水平状態に挾持した３Ｄファントム１０に、放射線治療装置（リニアック）のガントリ３０ａ，３０ｂ，３０ｃ，３０ｄ，３０ｅにて放射線を照射してコロナル面の線量分布を測定する（図１（１）参照）。 Next, the dose distribution on the coronal surface is measured by irradiating the 3D phantom 10 holding the radiation dose measuring body 20 in a horizontal state with the gantry 30a, 30b, 30c, 30d, 30e of the radiotherapy device (linac). (See FIG. 1 (1)).
　次いで、当該３Ｄファントムの位置を変えることなく、コントローラ（図示省略）でガントリ３０ａ，３０ｂ，３０ｃ，３０ｄ，３０ｅを９０°回転させ、その状態で当該３Ｄファントム１０に放射線を照射してサジタル面の線量分布を測定する（図１（２）参照）。尚、９０°回転方向は右回り、左回りの如何を問わず、またフィルムを挟む位置はファントムの中央でなくても構わない。 Next, without changing the position of the 3D phantom, the controller (not shown) rotates the gantry 30a, 30b, 30c, 30d, 30e by 90 °, and in that state, the 3D phantom 10 is irradiated with radiation to irradiate the sagittal surface. The dose distribution is measured (see FIG. 1 (2)). Note that the 90 ° rotation direction may be clockwise or counterclockwise, and the position where the film is sandwiched may not be the center of the phantom.
　因に、得られた実測値は、通常法と同様の手順で得られたコロナル面とサジタル面での計算値と比較することにより、治療計画で得られた結果が正しいか否か検証される。 By the way, the actual measurement value obtained is verified by comparing with the calculated value on the coronal surface and sagittal surface obtained by the same procedure as the normal method, whether the result obtained in the treatment plan is correct. .
　１０：３Ｄファントム
　１０ａ：上部ファントム部
　１０ｂ：下部ファントム部
　２０：放射線量測定体
　３０ａ，３０ｂ，３０ｃ，３０ｄ，３０ｅ：ガントリ
　５０：従来の３Ｄファントム
　６０：クランプ 10: 3D phantom 10a: Upper phantom part 10b: Lower phantom part 20: Radiation dose measuring body 30a, 30b, 30c, 30d, 30e: Gantry 50: Conventional 3D phantom 60: Clamp

Claims (1)

  1. 　９０°回転対称の断面形状を有する上下２分割体から成る３Ｄファントムの間に、放射線量測定体を水平状態に挾持せしめるステップと；当該放射線量測定体を水平状態に挾持した３Ｄファントムに、放射線治療装置のガントリにて放射線を照射してコロナル面の線量分布を測定するステップと；当該３Ｄファントムの位置を変えることなく、ガントリを９０°回転させ、その状態で当該３Ｄファントムに放射線を照射してサジタル面の線量分布を測定するステップとを有することを特徴とする３Ｄファントムを用いた放射線吸収線量の２次元分布測定方法。 A step of holding the radiation dose measuring body in a horizontal state between a 3D phantom composed of an upper and lower divided body having a 90 ° rotationally symmetric cross-sectional shape; a 3D phantom holding the radiation dose measuring body in a horizontal state; Irradiating radiation with the gantry of the treatment apparatus to measure the dose distribution on the coronal plane; rotating the gantry 90 ° without changing the position of the 3D phantom, and irradiating the 3D phantom with radiation in that state And measuring a dose distribution on the sagittal surface. A method for measuring a two-dimensional distribution of radiation absorbed dose using a 3D phantom.
PCT/JP2011/050841 2010-01-28 2011-01-19 Method of measuring two-dimensional distribution of radiological dose using 3d phantom WO2011093183A1 (en)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
CN102997992A (en) * 2012-11-26 2013-03-27 复旦大学 Optical dosimeter

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WO2008087952A1 (en) * 2007-01-16 2008-07-24 National University Corporation Okayama University Dose measuring method and phantom, and x-ray image picking-up device used for the dose measuring method

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WO2008087952A1 (en) * 2007-01-16 2008-07-24 National University Corporation Okayama University Dose measuring method and phantom, and x-ray image picking-up device used for the dose measuring method

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TORU KOJIMA: "3. Senryo Kensho no Jissai", JAPANESE SOCIETY OF RADIOLOGICAL TECHNOLOGY HOSHASEN CHIRYO BUNKAKAISHI, vol. 23, no. 1, April 2009 (2009-04-01) *

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Publication number Priority date Publication date Assignee Title
CN102997992A (en) * 2012-11-26 2013-03-27 复旦大学 Optical dosimeter

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