亨氏單位

亨氏單位（英語：Hounsfield unit，縮寫：HU），為亨氏量表（Hounsfield scale）阻射率（英语：Radiodensity）的數量尺度單位，命名自X射線電腦斷層掃描的發明人高弗雷·豪斯費爾德（Godfrey Newbold Hounsfield）。亨氏單位常用於X射線電腦斷層掃描，因此又稱為CT值（CT number）。

定義

亨氏單位為其所測量之介質的線性衰減係數的線性映射，其定義將蒸餾水與空氣在標準溫度與標準壓力下的阻射率（英语：Radiodensity）分別設為0 HU和-1,000 HU。因此，在線性衰減係數介於平均值間的體素中，其亨氏單位為：^[1]

$HU=1000\times {\frac {\mu -\mu _{\textrm {water}}}{\mu _{\textrm {water}}-\mu _{\textrm {air}}}}$

其中 $\mu _{\textrm {water}}$ 與 $\mu _{\textrm {air}}$ 分別為水與空氣的線性衰減係數。^[2]

由於空氣的線性衰減係數趨近於0，一個HU的變化相當於水線性衰減係數0.1%的變化。^[2]

原理

由於X射線電腦斷層掃描的功能在於將生物（主要是陸上生物，如人類）的體內結構成像化，因此採納上述標準作為所有介質的參照依據。^[2]

人體內各介質的亨氏單位值

亨氏單位僅適用於常見的雙能電腦斷層掃描（dual-energy CT scan），而不適用於錐狀射束電腦斷層掃描（cone beam CT scan）。^[3]

介質		亨氏單位
空氣		−1,000
脂肪		−120至−90^[4]
造影劑電腦斷層掃描（英语：Contrast CT）下的軟組織		+100至+300
骨骼	鬆質骨	+300至+400^[5]
骨骼	密質骨	+1,800至+1,900^[5]
頭部外傷	前數小時	+75至+100^[6]
	3日後	+65至+85^[6]
	10-14日後	+35至+40^[7]
其他血液	非凝血	+13^[8]至+50^[9]
其他血液	凝血	+50^[10]至+75^[8]^[10]
胸腔積液	漏出液（英语：Transudate）	+2至+15 ^[11]
胸腔積液	滲出液	+4至+33^[11]
其他體液	乳糜	−30^[12]
	水	0
	尿液	−5至+15^[4]
	膽汁	−5至+15^[4]
	腦脊液	+15
	膿瘍/膿	0^[13]至+20^[14] 或 +40^[14]至+45^[13]
	黏液	0^[15] - 130^[16]（超過70HU時進入高衰減）^[17]^[18]
薄壁組織	肺	−700至−600^[19]
	腎	+20至+45^[4]
	肝	60 ± 6^[20]
	淋巴結	+10至+20^[21]
	肌肉	+35至+55^[4]
	胸腺	+20至+40（兒童）^[22]
	胸腺	+20至+120（成人）^[22]
	白質	+20至+30
	灰質	+37至+45
膽結石	膽固醇石	+30至+100^[23]
膽結石	色素性膽結石	+90至+120^[23]
異物（英语：Foreign body）^[24]	一般窗戶玻璃	+500
	鋁、瀝青、車窗玻璃、玻璃瓶與其他石類	+2,100至+2,300
	石灰岩	+2,800
	銅	+14,000
	銀	+17,000
	鋼	+20,000
	金、鋼與黃銅	+30,000（可測量之上限）
耳垢		<0

亨氏單位常用於辨識腫瘤，以腎上腺腺瘤（英语：Adrenal adenoma）為例，當該腫瘤的阻射率（英语：Radiodensity）小於10 HU，則其脂肪成分偏高，代表該腫瘤有較大機率為良性腫瘤^[25]。

參見

參考資料

^ Lev, Michael; Gonzalez, Rodolfo. CT Angiography and CT Perfusion Imaging. ScienceDirect. 2002 [2020-12-20]. （原始内容存档于2020-11-12）（英语）.
^ ^2.0 ^2.1 ^2.2 DenOtter, Tami; Schubert, Johanna. Hounsfield Unit. 美國國家衛生院. 2020-05-11 [2020-12-20]. （原始内容存档于2021-12-06）（英语）.
^ De Vos, W.; Casselman, J.; Swennen, G.R.J. Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: A systematic review of the literature. International Journal of Oral and Maxillofacial Surgery. 2009-06, 38 (6): 609–625. PMID 19464146. doi:10.1016/j.ijom.2009.02.028.
^ ^4.0 ^4.1 ^4.2 ^4.3 ^4.4 Page 83 in: Herbert Lepor. Prostatic Diseases. W.B. Saunders Company. 2000. ISBN 9780721674162.
^ ^5.0 ^5.1 Birur, NPraveen; Patrick, Sanjana; Gurushanth, Keerthi; Raghavan, AShubhasini; Gurudath, Shubha. Comparison of gray values of cone-beam computed tomography with hounsfield units of multislice computed tomography: An in vitro study. Indian Journal of Dental Research. 2017年, 28 (1): 66–70. ISSN 0970-9290. PMID 28393820. doi:10.4103/ijdr.IJDR_415_16.
^ ^6.0 ^6.1 Fig 3 in: Rao, Murali Gundu. Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study. Journal of Clinical and Diagnostic Research. 2016, 10 (4): HC01–5. ISSN 2249-782X. PMC 4866129 . PMID 27190831. doi:10.7860/JCDR/2016/17207.7644.
^ Dr Rohit Sharma; A.Prof Frank Gaillard. Subdural haemorrhage. Radiopaedia. [2018-08-14]. （原始内容存档于2011-03-23）.
^ ^8.0 ^8.1 Page 263 in: Robert Fosbinder; Denise Orth. Essentials of Radiologic Science. Lippincott Williams & Wilkins. 2011. ISBN 9780781775540.
^ page 20.17 in: F W Wright. Radiology of the Chest and Related Conditions. CRC Press. 2001. ISBN 9780415281416.
^ ^10.0 ^10.1 page 17 in: Dr. Avital Fast; Dorith Goldsher. Navigating the Adult Spine: Bridging Clinical Practice and Neuroradiology. Demos Medical Publishing. 2006. ISBN 9781934559741.
^ ^11.0 ^11.1 Cullu, Nesat; Kalemci, Serdar; Karakas, Omer; Eser, Irfan; Yalcin, Funda; Boyaci, Fatma Nurefsan; Karakas, Ekrem. Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion. Diagnostic and Interventional Radiology. 2013, 20 (2): 116–20. ISSN 1305-3825. PMC 4463296 . PMID 24100060. doi:10.5152/dir.2013.13066.
^ Page 342 in: Luca Saba; Jasjit S. Suri. Multi-Detector CT Imaging: Principles, Head, Neck, and Vascular Systems, Volume 1. CRC Press. 2013. ISBN 9781439893845.
^ ^13.0 ^13.1 P. Sanchez de Medina Alba; C. Santos Montón; N. Calvo; K. El Karzazi; T. González de la Huebra Labrador; R. Corrales; N. Alegre Borge; Salamanca/ES. Liver abscesses: where do they come from?A review of the main types of liver abscesses and the correlation between their causes and the radiologic findings. ECR 2014. 2014 [2020-12-17]. doi:10.1594/ecr2014/C-1927. （原始内容存档于2019-01-12）.
^ ^14.0 ^14.1 Sasaki, Toru; Miyata, Rie; Hatai, Yoshiho; Makita, Kohzoh; Tsunoda, Koichi. Hounsfield unit values of retropharyngeal abscess-like lesions seen in Kawasaki disease. Acta Oto-Laryngologica. 2014, 134 (4): 437–440. ISSN 0001-6489. PMID 24512428. doi:10.3109/00016489.2013.878475.
^ K SAGGAR, A AHLUWALIA; P SANDHU, V KALIA. Mucocoele Of The Appendix (PDF). Ind J Radiol Imag. 2006, 16 (2). ^{[失效連結]}
^ Gaeta, Michele; Vinci, Sergio; Minutoli, Fabio; Mazziotti, Silvio; Ascenti, Giorgio; Salamone, Ignazio; Lamberto, Salvatore; Blandino, Alfredo. CT and MRI findings of mucin-containing tumors and pseudotumors of the thorax: pictorial review. European Radiology. 2001, 12 (1): 181–189. ISSN 0938-7994. PMID 11868096. doi:10.1007/s003300100934.
^ Subash S Phuyal; Mandeep Kumar MK Garg; Ritesh R Agarwal; Pankaj P Gupta; Arunaloke A Chakrabarti; Manavjit Singh MS Sandhu; Niranjan N Khandelwal. High-Attenuation Mucus Impaction in Patients With Allergic Bronchopulmonary Aspergillosis: Objective Criteria on High-Resolution Computed Tomography and Correlation With Serologic Parameters. Current Problems in Diagnostic Radiology. 2015-09-02.
^ Agarwal, Ritesh; Sehgal, Inderpaul Singh; Dhooria, Sahajal; Aggarwal, Ashutosh. Radiologic Criteria for the Diagnosis of High-Attenuation Mucus in Allergic Bronchopulmonary Aspergillosis. Chest. 2016, 149 (4): 1109–1110. ISSN 0012-3692. PMID 27055707. doi:10.1016/j.chest.2015.12.043.
^ Page 379 in: Ella A. Kazerooni; Barry H. Gross. Cardiopulmonary Imaging 4. Lippincott Williams & Wilkins. 2004. ISBN 9780781736558.
^ page 210 in: Erwin Kuntz; Hans-Dieter Kuntz. Hepatology, Principles and Practice: History, Morphology, Biochemistry, Diagnostics, Clinic, Therapy. Springer Science & Business Media. 2006. ISBN 9783540289777.
^ Page 58 in: G. Maatman. High-Resolution Computed Tomography of the Paranasal Sinuses and Pharynx and Related Regions: Impact of CT identification on diagnosis and patient management. Volume 12 of Series in Radiology. Springer Science & Business Media. 2012. ISBN 9789400942776.
^ ^22.0 ^22.1 Page 488 （页面存档备份，存于互联网档案馆） in: Jean-Claude Givel; Marco Merlini; David B. Clarke; Michael Dusmet. Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique. Springer Science & Business Media. 2012. ISBN 9783642710766.
^ ^23.0 ^23.1 Rambow A, Staritz M, Wosiewitz U, Mildenburger P, Thelen M, Meyer zum Büschenfelde KH. Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components. Eur J Clin Invest. 1990, 20 (4): 475–8. PMID 2121509. doi:10.1111/j.1365-2362.1990.tb01887.x.
^ Bolliger, Stephan A.; Oesterhelweg, Lars; Spendlove, Danny; Ross, Steffen; Thali, Michael J. Is Differentiation of Frequently Encountered Foreign Bodies in Corpses Possible by Hounsfield Density Measurement?. Journal of Forensic Sciences. 2009, 54 (5): 1119–1122. ISSN 0022-1198. PMID 19627414. doi:10.1111/j.1556-4029.2009.01100.x.
^ Perry J Horwich. Adrenal Adenoma Imaging. 2011-04-21 [2020-12-19] （英语）.

參考書籍

Feeman, Timothy G. The Mathematics of Medical Imaging: A Beginner's Guide. Springer Undergraduate Texts in Mathematics and Technology. Springer. 2010. ISBN 978-0387927114.

外部連結

Hounsfield unit. Medcyclopaedia. GE. [2020-12-17]. （原始内容存档于2012-04-04）.
Hounsfield Unit （页面存档备份，存于互联网档案馆） - fpnotebook.com
Introduction to CT physics (PDF). elsevierhealth.com. [2020-12-17]. （原始内容存档 (PDF)于2007-09-26）.
Imaging of deep brain stimulation leads using extended Hounsfield unit CT. Stereotact Funct Neurosurg. 2009;87(3):155-60. doi: 10.1159/000209296 （页面存档备份，存于互联网档案馆）

[1] Lev, Michael; Gonzalez, Rodolfo. CT Angiography and CT Perfusion Imaging. ScienceDirect. 2002 [2020-12-20]. （原始内容存档于2020-11-12）（英语）.

[NIH_HU-2] 2.0 ^2.1 ^2.2 DenOtter, Tami; Schubert, Johanna. Hounsfield Unit. 美國國家衛生院. 2020-05-11 [2020-12-20]. （原始内容存档于2021-12-06）（英语）.

[DEVOS-3] De Vos, W.; Casselman, J.; Swennen, G.R.J. Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: A systematic review of the literature. International Journal of Oral and Maxillofacial Surgery. 2009-06, 38 (6): 609–625. PMID 19464146. doi:10.1016/j.ijom.2009.02.028.

[Lepor2000-4] 4.0 ^4.1 ^4.2 ^4.3 ^4.4 Page 83 in: Herbert Lepor. Prostatic Diseases. W.B. Saunders Company. 2000. ISBN 9780721674162.

[BirurPatrick2017-5] 5.0 ^5.1 Birur, NPraveen; Patrick, Sanjana; Gurushanth, Keerthi; Raghavan, AShubhasini; Gurudath, Shubha. Comparison of gray values of cone-beam computed tomography with hounsfield units of multislice computed tomography: An in vitro study. Indian Journal of Dental Research. 2017年, 28 (1): 66–70. ISSN 0970-9290. PMID 28393820. doi:10.4103/ijdr.IJDR_415_16.

[Rao2016-6] 6.0 ^6.1 Fig 3 in: Rao, Murali Gundu. Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study. Journal of Clinical and Diagnostic Research. 2016, 10 (4): HC01–5. ISSN 2249-782X. PMC 4866129 . PMID 27190831. doi:10.7860/JCDR/2016/17207.7644.

[7] Dr Rohit Sharma; A.Prof Frank Gaillard. Subdural haemorrhage. Radiopaedia. [2018-08-14]. （原始内容存档于2011-03-23）.

[fosbinder2011-8] 8.0 ^8.1 Page 263 in: Robert Fosbinder; Denise Orth. Essentials of Radiologic Science. Lippincott Williams & Wilkins. 2011. ISBN 9780781775540.

[9] 20.17 in: F W Wright. Radiology of the Chest and Related Conditions. CRC Press. 2001. ISBN 9780415281416.

[fast2006-10] 10.0 ^10.1 page 17 in: Dr. Avital Fast; Dorith Goldsher. Navigating the Adult Spine: Bridging Clinical Practice and Neuroradiology. Demos Medical Publishing. 2006. ISBN 9781934559741.

[CulluKalemci2013-11] 11.0 ^11.1 Cullu, Nesat; Kalemci, Serdar; Karakas, Omer; Eser, Irfan; Yalcin, Funda; Boyaci, Fatma Nurefsan; Karakas, Ekrem. Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion. Diagnostic and Interventional Radiology. 2013, 20 (2): 116–20. ISSN 1305-3825. PMC 4463296 . PMID 24100060. doi:10.5152/dir.2013.13066.

[12] Page 342 in: Luca Saba; Jasjit S. Suri. Multi-Detector CT Imaging: Principles, Head, Neck, and Vascular Systems, Volume 1. CRC Press. 2013. ISBN 9781439893845.

[ecr-13] 13.0 ^13.1 P. Sanchez de Medina Alba; C. Santos Montón; N. Calvo; K. El Karzazi; T. González de la Huebra Labrador; R. Corrales; N. Alegre Borge; Salamanca/ES. Liver abscesses: where do they come from?A review of the main types of liver abscesses and the correlation between their causes and the radiologic findings. ECR 2014. 2014 [2020-12-17]. doi:10.1594/ecr2014/C-1927. （原始内容存档于2019-01-12）.

[SasakiMiyata2014-14] 14.0 ^14.1 Sasaki, Toru; Miyata, Rie; Hatai, Yoshiho; Makita, Kohzoh; Tsunoda, Koichi. Hounsfield unit values of retropharyngeal abscess-like lesions seen in Kawasaki disease. Acta Oto-Laryngologica. 2014, 134 (4): 437–440. ISSN 0001-6489. PMID 24512428. doi:10.3109/00016489.2013.878475.

[15] K SAGGAR, A AHLUWALIA; P SANDHU, V KALIA. Mucocoele Of The Appendix (PDF). Ind J Radiol Imag. 2006, 16 (2). ^{[失效連結]}

[GaetaVinci2001-16] Gaeta, Michele; Vinci, Sergio; Minutoli, Fabio; Mazziotti, Silvio; Ascenti, Giorgio; Salamone, Ignazio; Lamberto, Salvatore; Blandino, Alfredo. CT and MRI findings of mucin-containing tumors and pseudotumors of the thorax: pictorial review. European Radiology. 2001, 12 (1): 181–189. ISSN 0938-7994. PMID 11868096. doi:10.1007/s003300100934.

[17] Subash S Phuyal; Mandeep Kumar MK Garg; Ritesh R Agarwal; Pankaj P Gupta; Arunaloke A Chakrabarti; Manavjit Singh MS Sandhu; Niranjan N Khandelwal. High-Attenuation Mucus Impaction in Patients With Allergic Bronchopulmonary Aspergillosis: Objective Criteria on High-Resolution Computed Tomography and Correlation With Serologic Parameters. Current Problems in Diagnostic Radiology. 2015-09-02.

[AgarwalSehgal2016-18] Agarwal, Ritesh; Sehgal, Inderpaul Singh; Dhooria, Sahajal; Aggarwal, Ashutosh. Radiologic Criteria for the Diagnosis of High-Attenuation Mucus in Allergic Bronchopulmonary Aspergillosis. Chest. 2016, 149 (4): 1109–1110. ISSN 0012-3692. PMID 27055707. doi:10.1016/j.chest.2015.12.043.

[19] Page 379 in: Ella A. Kazerooni; Barry H. Gross. Cardiopulmonary Imaging 4. Lippincott Williams & Wilkins. 2004. ISBN 9780781736558.

[20] 210 in: Erwin Kuntz; Hans-Dieter Kuntz. Hepatology, Principles and Practice: History, Morphology, Biochemistry, Diagnostics, Clinic, Therapy. Springer Science & Business Media. 2006. ISBN 9783540289777.

[21] Page 58 in: G. Maatman. High-Resolution Computed Tomography of the Paranasal Sinuses and Pharynx and Related Regions: Impact of CT identification on diagnosis and patient management. Volume 12 of Series in Radiology. Springer Science & Business Media. 2012. ISBN 9789400942776.

[givel2012-22] 22.0 ^22.1 Page 488 （页面存档备份，存于互联网档案馆） in: Jean-Claude Givel; Marco Merlini; David B. Clarke; Michael Dusmet. Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique. Springer Science & Business Media. 2012. ISBN 9783642710766.

[pmid2121509-23] 23.0 ^23.1 Rambow A, Staritz M, Wosiewitz U, Mildenburger P, Thelen M, Meyer zum Büschenfelde KH. Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components. Eur J Clin Invest. 1990, 20 (4): 475–8. PMID 2121509. doi:10.1111/j.1365-2362.1990.tb01887.x.

[BolligerOesterhelweg2009-24] Bolliger, Stephan A.; Oesterhelweg, Lars; Spendlove, Danny; Ross, Steffen; Thali, Michael J. Is Differentiation of Frequently Encountered Foreign Bodies in Corpses Possible by Hounsfield Density Measurement?. Journal of Forensic Sciences. 2009, 54 (5): 1119–1122. ISSN 0022-1198. PMID 19627414. doi:10.1111/j.1556-4029.2009.01100.x.

[25] Perry J Horwich. Adrenal Adenoma Imaging. 2011-04-21 [2020-12-19] （英语）.

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