ศ┴❧┳ㆤ⛉ᏛᏛᏛ㝔 Ặ ྡ ட ࡵ ࠸ ಟ࠾ࡉࡴ Ꮫ ࡢ ✀ 㢮 ༤ኈ㸦ᗣ⛉Ꮫ㸧 Ꮫ グ ␒ ྕ ➨ 11 ྕ Ꮫᤵᖺ᭶᪥ ᖹᡂ 27 ᖺ 3 ᭶ 18 ᪥ Ꮫᤵࡢせ௳ Ꮫつ๎➨㸲᮲➨ 1 㡯ヱᙜ⪅ ┳ㆤᏛ◊✲⛉ᗣ⛉Ꮫᑓᨷ Ꮫ ㄽ ᩥ ྡ CT ᳨ᰝ࠾ࡅࡿಶேࡢయᆺࢆᫎࡋࡓ⿕ࡤࡃ⥺㔞ホ౯ἲࡢ㛤Ⓨ
Development of dose-evaluation methods in CT examinations with considering individual physical size
ᣦ ᑟ ᩍ ဨ ⏥ᩫ ᫂ᩍᤵ() ᑠᔱ ග᫂ㅮᖌ() ㄽ ᩥ ᑂ ᰝ ጤ ဨ ᰝ㸸బᆂ୍㑻ᩍᤵ ᰝ㸸ရᕝె‶ᩍᤵ࣭๓⏣ᚭ┴❧㝔㝔㛗 ㄽ ᩥ ෆ ᐜ ࡢ せ ᪨ ࠙┠ⓗࠚCT ⨨ࡢ⏝ࡀ㐍ࡴ୰ࠊ⿕ࡤࡃ⥺㔞ࡢቑຍࡀ༴ࡉࢀ࡚࠸ࡿࠋࡑࡇ࡛ࠊCT ᳨ᰝ࠾ࡅ ࡿேయ⮚ჾࡢ⿕ࡤࡃ⥺㔞ࢆ᥎ᐃࡍࡿࡓࡵࠊࣔࣥࢸ࢝ࣝࣟἲࢆ⏝ࡋࡓࠊImPACT ἲࡸ CT-EXPO ἲࡀ㛤Ⓨࡉࢀ⏝ࡉࢀ࡚᮶ࡓࠋࡋࡋࠊࡇࡢࢶ࣮ࣝ࠾ࡅࡿ⥺㔞ホ౯ࡣḢ⡿ேࡢయ᱁࠾ࡅࡿ⥺㔞࡛ ࠶ࡾࠊయ᱁ࡢᑠࡉ࠸᪥ᮏேࡢሙྜࡣ⥺㔞᥎ᐃ್ㄗᕪࢆ⏕ࡌࡿ⪃࠼ࡽࢀࡿࠋࡲࡓࠊ⏝ࡍࡿࣇ ࣥࢺ࣒ࡣᩘᘧ࡛సᡂࡉࢀࡓయᆺ࡛࠶ࡾࠊᐇ㝿ࡢேయࡢ⮚ჾᑐࡋ࡚ࡢ⥺㔞ホ౯࡛ࡣ࡞࠸ࠋ ᪥ᮏ࠾࠸࡚ࡣࠊศ┴❧┳ㆤ⛉ᏛᏛ᪥ᮏཎᏊຊ◊✲㛤Ⓨᶵᵓ࡛ඹྠ㛤Ⓨࡉࢀࡓ WAZA-ARI ࠸࠺⥺㔞ィ⟬ Web ࢩࢫࢸ࣒ࡀᐇ⏝ࡉࢀ࡚࠸ࡿࠋࡇࡢࢩࢫࢸ࣒࡛ࡣ᪥ᮏேࡢᶆ‽యᆺ࡛ࡢ⥺㔞ホ ౯ࢆ⾜࠺ࡓࡵࠊ᪥ᮏཎᏊຊ◊✲㛤Ⓨᶵᵓ࠾࠸࡚㛤ⓎࡉࢀࡓࠊࠕJM-103ࠖࠊࠕJF-103ࠖ࡞ࠊࡼࡾ᪥ ᮏேࡢᶆ‽యᆺ㏆࡙ࡅࡓ࣎ࢡࢭࣝࣇࣥࢺ࣒ࢆ⏝ࡋ࡚ࠊPHITS ࢥ࣮ࢻࡼࡿࣔࣥࢸ࢝ࣝࣟἲࢆ ⏝ࡋࡓ⮚ჾࡢ⥺㔞ホ౯ࢆ⾜ࡗ࡚࠸ࡿࠋ⏝ࡋࡓ᪥ᮏேࡢᶆ‽యᆺࡣࠊ⏨ᛶࡣ㌟㛗 171cmࠊయ㔜 65kg 㸦JM-103㸧ࠊࡲࡓዪᛶࡣ㌟㛗 155cmࠊయ㔜 52kg㸦JF-103㸧࡛࠶ࡿࠋࡋࡋ࡞ࡀࡽࡇࡢ WAZA-ARI ࠾ࡅࡿ᥎ᐃ⥺㔞࠾࠸࡚ࡶᶆ‽యᆺ࠾ࡅࡿ⮚ჾ⥺㔞ࡢホ౯࡛࠶ࡾࠊᐇ㝿ࡢ⮫ᗋ࠾ࡅࡿಶูࡢయ ᆺࢆᫎࡋࡓ⥺㔞ホ౯࡛ࡣ࡞࠸ࠋࡋࡓࡀࡗ࡚ṇ☜࡞⮚ჾ⥺㔞ࢆ⟬ᐃࡍࡿࡓࡵࡣࠊJM ࠾ࡼࡧ JF ࣇ ࣥࢺ࣒ᐇ㝿ࡢయᆺࡢᕪࡽ⏕ࡎࡿㄗᕪࢆ⿵ṇࡍࡿ᪉ἲࡢ㛤Ⓨࡀᚲせ࡛࠶ࡿࠋࡑࡇ࡛ࠊᮏ◊✲࡛ ࡣࠊࡇࢀࡲ࡛◊✲ࡉࢀ࡚ࡁࡓ WAZA-ARI ࡞ࡢ◊✲ᡂᯝࢆࡩࡲ࠼࡚ࠊ⮫ᗋ࡛㐼㐝ࡍࡿ᪥ᮏேࡢ୍⯡ ⓗ࡞యᆺ࠾࠸࡚ࠊ⮚ჾ⥺㔞ࡢ⿵ṇ᪉ἲࢆ㛤Ⓨࡍࡿࡇࢆ┠ⓗࡋ࡚࠸ࡿࠋ ࠙◊✲ 1ࠚ⮫ᗋ CT ᳨ᰝࢹ࣮ࢱࡽࠊJMࠊJF ࣇࣥࢺ࣒ྠ➼࡞యᆺ࠾ࡼࡧ⑭ࡏᙧࠊኴࡾᆺࡢయᆺ ࢆ᭷ࡍࡿࠊ⏨ᛶ 11 యࠊዪᛶ 10 యࢆ↓సⅭ㑅ࡧࠊࡑࢀࡽࡢయᆺ㸦APࠊLATࠊ࿘ᅖ㛗࡞㸧ࢆ⮬స ࡢ CT ࢹ࣮ࢱ࣎ࢡࢭࣝኚࢶ࣮ࣝࡢయᆺィ ᶵ⬟ࢆ⏝ࡋ࡚ィ ࡋࡓࠋேయࡢయᆺㄪᰝࡘ࠸࡚ࡣࠊ ࡇࢀࡲ࡛ከࡃࡢ◊✲ࡀ࡞ࡉࢀ࡚࠾ࡾࠊᚑ᮶ࡽయ㔜 AP㸪LATࠊ࿘ᅖ㛗➼ࡢ㛵ಀࡢẚ㍑ࡀ࡞ࡉࢀ࡚ ࠸ࡿࠋᮏ◊✲࡛ࡣࠊࡑࢀࡽࡢ᪉ἲ௨እࡶࠊBMI ࡸ᭷ຠ┤ᚄ㸦ED㸧࠸࠺ᣦᶆࢆ⟬ᐃࡋࠊࡑࢀࡽࡢ ᩘ್ࡢ㛵ಀࢆㄪࡓࠋࡲࡓࠊ⮫ᗋࢹ࣮ࢱࡽ⫵ࠊᚰ⮚ࠊ⫶ࠊ⫢⮚ࠊ⫹ࡢ࠺ࠊ⭈⮚ࠊ⮅⮚ࠊ⭁⮚ࠊ⭤ ⬔ࠊᏊᐑ࡞ࡢྛ⮚ჾࡢయ✚ࢆィ ࡋࠊయ㔜ࡢ㛵ಀࢆศᯒࡋࡓࠋࡑࡢ⤖ᯝࠊ⏨ᛶࡢሙྜࠊ⮚ჾయ 㔜ࡢ㛫᭷ព࡞㛵ಀᛶࡣㄆࡵࡽࢀ࡞ࡗࡓࠋࡋࡋࠊዪᛶࡢሙྜ࠸ࡃࡘࡢ⮚ჾ㸦⫹ࡢ࠺ࠊ⭈⮚ࠊ⭁ ⮚ࠊ⭤⬔㸧࠾࠸࡚ࠊయ㔜⮚ჾయ✚ࡢ㛫୍ᐃࡢ㛵ಀᛶࡀㄆࡵࡽࢀࡓࠋ ࠙◊✲ 2ࠚᮏ◊✲ࡢ᭱⤊┠ᶆ࡛࠶ࡿయᆺࡢ㐪࠸ࡼࡿ⥺㔞ホ౯ࡣࠊPHITS ࢥ࣮ࢻୖ࡛ࠊCT ⨨ࢆᵓ ⠏ࡋࠊ᭦๓㏙ࡋࡓ⮫ᗋࢹ࣮ࢱࡽసᡂࡋࡓேయ࣎ࢡࢭࣝࣇࣥࢺ࣒ᑐࡋ࡚ X ⥺↷ᑕࢆ⾜࠺ࢩ࣑ ࣮ࣗࣞࢩࣙࣥࢆᐇࡋ࡚ࠊேయࡢྛ⮚ჾࡢ⿕ࡤࡃ⥺㔞ࡢ᥎ᐃࢆ⾜ࡗࡓࠋࡇࢀࡽࡢㄪᰝ࠾ࡼࡧᐇ㦂ࡼ ࡿ⤖ᯝࡋ࡚ࠊᡂே᪥ᮏே⏨ዪࡢయᆺࡢ≉ᚩࡽࠊ᪥ᮏேᶆ‽࡛࠶ࡿ JMࠊJF ࣇࣥࢺ࣒⮫ᗋࢹ ࣮ࢱࡽࠊ᭷ຠ┤ᚄ(ED) CT ᳨ᰝࡢ⮚ჾ⥺㔞ࡢ㛵ಀᛶࢆ᫂ࡽࡍࡿࡇࡀ࡛ࡁࡓࠋࡲࡓࠊ JMࠊJF ࣇࣥࢺ࣒ࡢ⮚ჾ⥺㔞ࡢ್⮫ᗋࢹ࣮ࢱࡢ⮚ჾ⥺㔞ࡢẚ㍑ࢆ⾜࠸ࠊ᪥ᮏேᶆ‽࡛࠶ࡿ JMࠊ JF ࣇࣥࢺ࣒ࡢ⮚ჾ⥺㔞ࡀࡶࡘಶேయᆺࡢ㐪࠸ࡀࡶࡓࡽࡍㄗᕪࡢ᥎ᐃࢆ⾜࠺ࡇࡀ࡛ࡁࡓࠋ ࠙⤖ㄽࠚᮏ◊✲ࡢ⤖ᯝࠊJMࠊJF ࣇࣥࢺ࣒యᆺࡢ␗࡞ࡿ⮫ᗋ࠾ࡅࡿ⿕᳨⪅ࡢ CT ᳨ᰝࡢࠊ⮚ ჾ⿕ࡤࡃ⥺㔞ࢆs10%௨ෆ࡛᥎ᐃࡍࡿࡇࡀྍ⬟࡛࠶ࡿࡇࢆ♧ࡋࡓࠋ⏨ዪࡢయᆺࡣ␗࡞ࡿࡀࠊ⮚ჾ ⥺㔞᭷ຠ┤ᚄࡢ㛵ಀࡣࠊ⏨ዪࡢ㐪࠸ࡣ᭷ព࡞ࡶࡢ࡛ࡣ࡞࠸ࡓࡵࠊ⮚ჾ⥺㔞ࢆ᥎ᐃࡍࡿ㝿ࡣࠊ᭷ ຠ┤ᚄࢆ⏝࠸࡚ᶆ‽ࣇࣥࢺ࣒ࡢ⮚ჾ⥺㔞ᑐࡋ࡚⏨ዪྠ୍ࡢ⿵ṇᘧࢆ⏝ࡍࡿࡇࡀ࡛ࡁࡿࡇ ࢆ♧ࡋࡓࠋ
ศ┴❧┳ㆤ⛉ᏛᏛᏛ㝔
Abstract
࠙ObjectiveࠚIn this study, it aims to develop correction coefficients for estimating organ doses to patients of any size attended to daily clinical practice. These results can be used for computer tomography (CT) dose calculators such as WAZA-ARI.
࠙Study 1ࠚWe randomly selected 11 males and 10 females from the clinical data with different body size from the average Japanese size like the JM and JF phantom. The body size can be characterized by AP, LAT and perimeter measured by using a voxel-conversion tool for CT image data. Since there are a number of studies for categorization of human body types so far, the relation with weight, AP, LAT, and perimeter has been already compared. This study calculated the indexes called BMI and effective diameter (ED) for each patient other than previous methods, and then examined the relation of those calculated values with organ sizes. Furthermore, this study also measured the volume of each organ from the clinical data such as lung, heart, stomach, liver, gallbladder, kidney, pancreas, spleen, urinary bladder, and womb, and analyzed their relations with body weights. As a result, no significant relation was observed between organs volumes and body weights in males. In females, however, a statistically significant relation was observed between body weights and organ volumes only in several organs, gallbladder, kidney, spleen, and urinary bladder.
࠙Study 2ࠚCalculation of organ doses was conducted by the Monte-Carlo simulations using a PHITS code where X-ray was irradiated against human voxel phantoms by structuring a quasi-CT scanner. As the results of the Monte-Carlo simulations, we analyzed the relation between organ doses and ED in JM, JF and patient phantoms, and obtained the equations for predicting patient-specific organ doses using ED. In addition, we compared patient-specific organ doses with the ED-modified organ doses given by the WAZA-ARI that uses the JM and JF phantoms with average Japanese sizes. The difference in males was approximately 10% in the stomach and less than 7% in other organs. The ED-based equation by combining males and females provided a better agreement with the average errors of -4.8% in females and -6.2% in males. However, in some cases, ED-based prediction was inconsistent with patient-specific organ doses, particular in heart and stomach. It was found that the size of the lung largely influenced x-ray transport and consequently the organ doses departed from the ED-based prediction.
࠙ConclusionࠚThis study provided how to patient-specific organ doses from adult body CT scans for a patient with the different body size from JM and JM phantom with an error of ±10% or lower.
ㄽ ᩥ ᑂ ᰝ ࡢ ⤖ ᯝ ࡢ せ ᪨ &7᳨ᰝࡢ⿕ࡤࡃ⥺㔞ࡢホ౯ἲࢆᨵၿࡍࡿࡓࡵࠊேయࡢᶆ‽ⓗ࡞ᩘ್ࣔࢹࣝ㸦ࣇࣥࢺ࣒㸧ࢆ⏝࠸ ࡿᚑ᮶ࡢࢥࣥࣆ࣮ࣗࢱࢩ࣑࣮ࣗࣞࢩࣙࣥࡼࡿ᥎ᐃ್ᑐࡋ࡚ಶேࡢయᆺࡢᕪ␗ࡼࡿ⿵ṇࢆヨࡳ ࡓ◊✲࡛࠶ࡿࠋ་⒪⿕ࡤࡃ㛵ࡍࡿ㆟ㄽࡢ๓ᥦࡋ࡚㸪ᝈ⪅ಶேࡢ⿕ࡤࡃ⥺㔞ࢆ⢭ᐦホ౯ࡍࡿࡇ ࡣ㔜せ࡛࠶ࡾࠊᮏ◊✲ࡢ┠ᣦࡍࡶࡢࡢព⩏ࡣࡁ࠸ࠋᮏㄽᩥࡢ୰ᚰࡣ㸪ᵝࠎ࡞యᆺࡢࣇࣥࢺ࣒ࢆ⏝ ࠸ࠊ3+,76ࢥ࣮ࢻࡼࡿ⿕ࡤࡃ⥺㔞᥎ᐃ್యᆺࢆ௦⾲ࡍࡿ㌟యィ 㡯┠⩌ࡢ㛵㐃ࢆᅇᖐศᯒ࡛ゎ ᯒࡍࡿࡇ࡛ࠊᝈ⪅⬚⭡㒊ࡢ᭷ຠ┤ᚄࢆ⏝࠸ࡓ⿵ṇ᪉ἲࡀࡶࡗࡶ᭷ຠ࡛࠶ࡿࡇࢆ♧ࡋࡓ㒊ศ࡛࠶ ࡿࠋࡲࡓࠊࡑࡢ๓ẁ㝵࡞ࡿᵝࠎ࡞యᆺࢆᣢࡘ⏨ዪィྡࡢ&7⏬ീࢆゎᯒࡋࠊ⮚ჾࡢ✀ูࡸ⨨ࢆᩘ ್ࢹ࣮ࢱኚࡋ㸪ࢩ࣑࣮ࣗࣞࢩࣙࣥ⏝ࡢࣇࣥࢺ࣒ࢆᵓ⠏ࡍࡿ㒊ศࡣ㸪ከ࡞㛫ࢆせࡍࡿປస࡛ ࠶ࡿࡶࠊ⮚ჾࡢ⨨ࡸࡁࡉࡢࢹ࣮ࢱࡑࡢศᯒࡋ࡚ࡶ⯆῝࠸ࡶࡢ࡛࠶ࡿࠋ ᚋࡣ㸪◊✲ᡂᯝࡢ⮫ᗋ࠾ࡅࡿ᳨ᰝࡢ⿕ࡤࡃ⥺㔞グ㘓ࢩࢫࢸ࣒ࡢᑟධ㸪యᆺࢹ࣮ࢱᩘ್ ࡢᡭἲࢆࡉࡽᨵၿࡋࠊయᆺࢹ࣮ࢱࢆ㏣ຍࡍࡿࡇࡼࡿಶே⿕ࡤࡃ⥺㔞᥎ᐃࡢ᭦࡞ࡿ⢭ᗘྥୖࢆᮇ ᚅࡍࡿࡶࡢ࡛࠶ࡿࡀࠊࡇࡢ◊✲ㄽᩥ࡛ࡢᡂᯝࡣ㸪ᮏᏛࡢᗣ⛉Ꮫᑓᨷ༤ኈᚋᮇㄢ⛬ࡢᏛㄽᩥࡋ࡚ ༑ศ┦ᛂࡋ࠸ࡶࡢุ᩿ࡍࡿࠋ
