The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?
Purpose: To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position duri...
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| Veröffentlicht in: | Medical physics (Lancaster) 2013-01, Vol.40 (1), p.011911-n/a |
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| creator | Perisinakis, Kostas Seimenis, Ioannis Tzedakis, Antonis Papadakis, Antonios E. Damilakis, John |
| description | Purpose:
To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position during the examination and bowtie filter used on peak tissue doses.
Methods:
The peak doses to eye lens, skin, brain, and RBM were measured in 106 individual-specific adult head phantoms subjected to the standard low-dose brain perfusion CT on a 256-slice CT scanner using a novel Monte Carlo simulation software dedicated for patient CT dosimetry. Peak tissue doses were compared to corresponding thresholds for induction of cataract, erythema, cerebrovascular disease, and depression of hematopoiesis, respectively. The effects of patient head size/shape, head position during acquisition and bowtie filter used on resulting peak patient tissue doses were investigated. The effect of eye-lens position in the scanned head region was also investigated. The effect of miscentering and use of narrow bowtie filter on image quality was assessed.
Results:
The mean peak doses to eye lens, skin, brain, and RBM were found to be 124, 120, 95, and 163 mGy, respectively. The effect of patient head size and shape on peak tissue doses was found to be minimal since maximum differences were less than 7%. Patient head miscentering and bowtie filter selection were found to have a considerable effect on peak tissue doses. The peak eye-lens dose saving achieved by elevating head by 4 cm with respect to isocenter and using a narrow wedge filter was found to approach 50%. When the eye lies outside of the primarily irradiated head region, the dose to eye lens was found to drop to less than 20% of the corresponding dose measured when the eye lens was located in the middle of the x-ray beam. Positioning head phantom off-isocenter by 4 cm and employing a narrow wedge filter results in a moderate reduction of signal-to-noise ratio mainly to the peripheral region of the phantom.
Conclusions:
Despite typical peak doses to skin, eye lens, brain, and RBM from the standard low-dose brain perfusion 256-slice CT protocol are well below the corresponding thresholds for the induction of erythema, cataract, cerebrovascular disease, and depression of hematopoiesis, respectively, every effort should be made toward optimization of the procedure and minimization of dose received by these tissues. The current study |
| doi_str_mv | 10.1118/1.4773042 |
| format | Article |
| fullrecord | <record><control><sourceid>proquest_wiley</sourceid><recordid>TN_cdi_wiley_primary_10_1118_1_4773042_MP3042</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><sourcerecordid>1273355115</sourcerecordid><originalsourceid>FETCH-LOGICAL-c4212-47c969484da057c2a2a949e638f1d61d03c7b3b0e003d51df537e3eed92c7e0b3</originalsourceid><addsrcrecordid>eNp9kc9u1DAQxiMEokvhwAugkbhQ1LT-l2TDBVUroEhFcFjOkWOPWdPETu2EVXk33g0vCRUSgpOl8W---Wa-LHtKyRmldH1Oz0RVcSLYvWzFRMVzwUh9P1sRUoucCVIcZY9i_EoIKXlBHmZHjLN6TQlbZT-2OwQ0BtUI3sAOpYZov-N53MkBT6G3UaEbMVj35RSk09D6_WgRjO1SFbyDAeU1DDIV3QijjXFC0D5iBBN8D73XGBy0QdoDG8wUbepiRZnHziqEzfYVXPo9KOlgj2mis31yAGNyFmy8BuMDaEzTDl9xtGoxHF8_zh4Y2UV8srzH2ee3b7aby_zq47v3m4urXAlGWS4qVZe1WAstSVEpJpmsRY0lXxuqS6oJV1XLW4KEcF1QbQpeIUfUNVMVkpYfZ89nXZ_GN1HZEdVOeeeSi4alY9d0TRP1YqaG4G8mjGPz63pdJx36KTaUVZwXBaVFQk9mVAUfY0DTDMH2Mtw2lDSHTBvaLJkm9tkiO7U96jvyd4gJyGdgbzu8_bdS8-HTIvhy5g-LpNy8u-v55sMf_KDN_-C_rf4EA3zGdg</addsrcrecordid><sourcetype>Open Access Repository</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype><pqid>1273355115</pqid></control><display><type>article</type><title>The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?</title><source>MEDLINE</source><source>Wiley Online Library Journals Frontfile Complete</source><source>Alma/SFX Local Collection</source><creator>Perisinakis, Kostas ; Seimenis, Ioannis ; Tzedakis, Antonis ; Papadakis, Antonios E. ; Damilakis, John</creator><creatorcontrib>Perisinakis, Kostas ; Seimenis, Ioannis ; Tzedakis, Antonis ; Papadakis, Antonios E. ; Damilakis, John</creatorcontrib><description>Purpose:
To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position during the examination and bowtie filter used on peak tissue doses.
Methods:
The peak doses to eye lens, skin, brain, and RBM were measured in 106 individual-specific adult head phantoms subjected to the standard low-dose brain perfusion CT on a 256-slice CT scanner using a novel Monte Carlo simulation software dedicated for patient CT dosimetry. Peak tissue doses were compared to corresponding thresholds for induction of cataract, erythema, cerebrovascular disease, and depression of hematopoiesis, respectively. The effects of patient head size/shape, head position during acquisition and bowtie filter used on resulting peak patient tissue doses were investigated. The effect of eye-lens position in the scanned head region was also investigated. The effect of miscentering and use of narrow bowtie filter on image quality was assessed.
Results:
The mean peak doses to eye lens, skin, brain, and RBM were found to be 124, 120, 95, and 163 mGy, respectively. The effect of patient head size and shape on peak tissue doses was found to be minimal since maximum differences were less than 7%. Patient head miscentering and bowtie filter selection were found to have a considerable effect on peak tissue doses. The peak eye-lens dose saving achieved by elevating head by 4 cm with respect to isocenter and using a narrow wedge filter was found to approach 50%. When the eye lies outside of the primarily irradiated head region, the dose to eye lens was found to drop to less than 20% of the corresponding dose measured when the eye lens was located in the middle of the x-ray beam. Positioning head phantom off-isocenter by 4 cm and employing a narrow wedge filter results in a moderate reduction of signal-to-noise ratio mainly to the peripheral region of the phantom.
Conclusions:
Despite typical peak doses to skin, eye lens, brain, and RBM from the standard low-dose brain perfusion 256-slice CT protocol are well below the corresponding thresholds for the induction of erythema, cataract, cerebrovascular disease, and depression of hematopoiesis, respectively, every effort should be made toward optimization of the procedure and minimization of dose received by these tissues. The current study provides evidence that the use of the narrower bowtie filter available may considerably reduce peak absorbed dose to all above radiosensitive tissues with minimal deterioration in image quality. Considerable reduction in peak eye-lens dose may also be achieved by positioning patient head center a few centimeters above isocenter during the exposure.</description><identifier>ISSN: 0094-2405</identifier><identifier>EISSN: 2473-4209</identifier><identifier>DOI: 10.1118/1.4773042</identifier><identifier>PMID: 23298102</identifier><identifier>CODEN: MPHYA6</identifier><language>eng</language><publisher>United States: American Association of Physicists in Medicine</publisher><subject>60 APPLIED LIFE SCIENCES ; Adult ; BLOOD FORMATION ; bone ; BONE MARROW ; bow‐tie filter ; BRAIN ; Brain - diagnostic imaging ; brain perfusion ; CATARACTS ; Computed tomography ; COMPUTER CODES ; Computerised tomographs ; computerised tomography ; COMPUTERIZED SIMULATION ; COMPUTERIZED TOMOGRAPHY ; deterministic effects ; Digital computing or data processing equipment or methods, specially adapted for specific applications ; Diseases ; DOSIMETRY ; Dosimetry/exposure assessment ; ERYTHEMA ; eye ; filtering theory ; HEAD ; Head - anatomy & histology ; HEALTH HAZARDS ; Humans ; Image data processing or generation, in general ; IMAGE PROCESSING ; Image scanners ; Medical image noise ; medical image processing ; Medical image quality ; Medical imaging ; minimisation ; misentering ; MONTE CARLO METHOD ; Monte Carlo methods ; Monte Carlo simulations ; Multislice ; Numerical optimization ; Organ Size ; Organs at Risk - radiation effects ; patient dose ; Patient Positioning ; PATIENTS ; Perfusion Imaging - methods ; PHANTOMS ; Probability ; Radiation Dosage ; RADIATION DOSES ; RADIATION PROTECTION AND DOSIMETRY ; Radiation Tolerance ; Radiometry ; Risk ; SIGNAL-TO-NOISE RATIO ; SKELETON ; SKIN ; Software ; Tissues ; Tomography, X-Ray Computed - methods ; X RADIATION</subject><ispartof>Medical physics (Lancaster), 2013-01, Vol.40 (1), p.011911-n/a</ispartof><rights>American Association of Physicists in Medicine</rights><rights>2013 American Association of Physicists in Medicine</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c4212-47c969484da057c2a2a949e638f1d61d03c7b3b0e003d51df537e3eed92c7e0b3</citedby><cites>FETCH-LOGICAL-c4212-47c969484da057c2a2a949e638f1d61d03c7b3b0e003d51df537e3eed92c7e0b3</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://onlinelibrary.wiley.com/doi/pdf/10.1118%2F1.4773042$$EPDF$$P50$$Gwiley$$H</linktopdf><linktohtml>$$Uhttps://onlinelibrary.wiley.com/doi/full/10.1118%2F1.4773042$$EHTML$$P50$$Gwiley$$H</linktohtml><link.rule.ids>230,314,780,784,885,1417,27923,27924,45573,45574</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/23298102$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink><backlink>$$Uhttps://www.osti.gov/biblio/22099181$$D View this record in Osti.gov$$Hfree_for_read</backlink></links><search><creatorcontrib>Perisinakis, Kostas</creatorcontrib><creatorcontrib>Seimenis, Ioannis</creatorcontrib><creatorcontrib>Tzedakis, Antonis</creatorcontrib><creatorcontrib>Papadakis, Antonios E.</creatorcontrib><creatorcontrib>Damilakis, John</creatorcontrib><title>The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?</title><title>Medical physics (Lancaster)</title><addtitle>Med Phys</addtitle><description>Purpose:
To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position during the examination and bowtie filter used on peak tissue doses.
Methods:
The peak doses to eye lens, skin, brain, and RBM were measured in 106 individual-specific adult head phantoms subjected to the standard low-dose brain perfusion CT on a 256-slice CT scanner using a novel Monte Carlo simulation software dedicated for patient CT dosimetry. Peak tissue doses were compared to corresponding thresholds for induction of cataract, erythema, cerebrovascular disease, and depression of hematopoiesis, respectively. The effects of patient head size/shape, head position during acquisition and bowtie filter used on resulting peak patient tissue doses were investigated. The effect of eye-lens position in the scanned head region was also investigated. The effect of miscentering and use of narrow bowtie filter on image quality was assessed.
Results:
The mean peak doses to eye lens, skin, brain, and RBM were found to be 124, 120, 95, and 163 mGy, respectively. The effect of patient head size and shape on peak tissue doses was found to be minimal since maximum differences were less than 7%. Patient head miscentering and bowtie filter selection were found to have a considerable effect on peak tissue doses. The peak eye-lens dose saving achieved by elevating head by 4 cm with respect to isocenter and using a narrow wedge filter was found to approach 50%. When the eye lies outside of the primarily irradiated head region, the dose to eye lens was found to drop to less than 20% of the corresponding dose measured when the eye lens was located in the middle of the x-ray beam. Positioning head phantom off-isocenter by 4 cm and employing a narrow wedge filter results in a moderate reduction of signal-to-noise ratio mainly to the peripheral region of the phantom.
Conclusions:
Despite typical peak doses to skin, eye lens, brain, and RBM from the standard low-dose brain perfusion 256-slice CT protocol are well below the corresponding thresholds for the induction of erythema, cataract, cerebrovascular disease, and depression of hematopoiesis, respectively, every effort should be made toward optimization of the procedure and minimization of dose received by these tissues. The current study provides evidence that the use of the narrower bowtie filter available may considerably reduce peak absorbed dose to all above radiosensitive tissues with minimal deterioration in image quality. Considerable reduction in peak eye-lens dose may also be achieved by positioning patient head center a few centimeters above isocenter during the exposure.</description><subject>60 APPLIED LIFE SCIENCES</subject><subject>Adult</subject><subject>BLOOD FORMATION</subject><subject>bone</subject><subject>BONE MARROW</subject><subject>bow‐tie filter</subject><subject>BRAIN</subject><subject>Brain - diagnostic imaging</subject><subject>brain perfusion</subject><subject>CATARACTS</subject><subject>Computed tomography</subject><subject>COMPUTER CODES</subject><subject>Computerised tomographs</subject><subject>computerised tomography</subject><subject>COMPUTERIZED SIMULATION</subject><subject>COMPUTERIZED TOMOGRAPHY</subject><subject>deterministic effects</subject><subject>Digital computing or data processing equipment or methods, specially adapted for specific applications</subject><subject>Diseases</subject><subject>DOSIMETRY</subject><subject>Dosimetry/exposure assessment</subject><subject>ERYTHEMA</subject><subject>eye</subject><subject>filtering theory</subject><subject>HEAD</subject><subject>Head - anatomy & histology</subject><subject>HEALTH HAZARDS</subject><subject>Humans</subject><subject>Image data processing or generation, in general</subject><subject>IMAGE PROCESSING</subject><subject>Image scanners</subject><subject>Medical image noise</subject><subject>medical image processing</subject><subject>Medical image quality</subject><subject>Medical imaging</subject><subject>minimisation</subject><subject>misentering</subject><subject>MONTE CARLO METHOD</subject><subject>Monte Carlo methods</subject><subject>Monte Carlo simulations</subject><subject>Multislice</subject><subject>Numerical optimization</subject><subject>Organ Size</subject><subject>Organs at Risk - radiation effects</subject><subject>patient dose</subject><subject>Patient Positioning</subject><subject>PATIENTS</subject><subject>Perfusion Imaging - methods</subject><subject>PHANTOMS</subject><subject>Probability</subject><subject>Radiation Dosage</subject><subject>RADIATION DOSES</subject><subject>RADIATION PROTECTION AND DOSIMETRY</subject><subject>Radiation Tolerance</subject><subject>Radiometry</subject><subject>Risk</subject><subject>SIGNAL-TO-NOISE RATIO</subject><subject>SKELETON</subject><subject>SKIN</subject><subject>Software</subject><subject>Tissues</subject><subject>Tomography, X-Ray Computed - methods</subject><subject>X RADIATION</subject><issn>0094-2405</issn><issn>2473-4209</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2013</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNp9kc9u1DAQxiMEokvhwAugkbhQ1LT-l2TDBVUroEhFcFjOkWOPWdPETu2EVXk33g0vCRUSgpOl8W---Wa-LHtKyRmldH1Oz0RVcSLYvWzFRMVzwUh9P1sRUoucCVIcZY9i_EoIKXlBHmZHjLN6TQlbZT-2OwQ0BtUI3sAOpYZov-N53MkBT6G3UaEbMVj35RSk09D6_WgRjO1SFbyDAeU1DDIV3QijjXFC0D5iBBN8D73XGBy0QdoDG8wUbepiRZnHziqEzfYVXPo9KOlgj2mis31yAGNyFmy8BuMDaEzTDl9xtGoxHF8_zh4Y2UV8srzH2ee3b7aby_zq47v3m4urXAlGWS4qVZe1WAstSVEpJpmsRY0lXxuqS6oJV1XLW4KEcF1QbQpeIUfUNVMVkpYfZ89nXZ_GN1HZEdVOeeeSi4alY9d0TRP1YqaG4G8mjGPz63pdJx36KTaUVZwXBaVFQk9mVAUfY0DTDMH2Mtw2lDSHTBvaLJkm9tkiO7U96jvyd4gJyGdgbzu8_bdS8-HTIvhy5g-LpNy8u-v55sMf_KDN_-C_rf4EA3zGdg</recordid><startdate>201301</startdate><enddate>201301</enddate><creator>Perisinakis, Kostas</creator><creator>Seimenis, Ioannis</creator><creator>Tzedakis, Antonis</creator><creator>Papadakis, Antonios E.</creator><creator>Damilakis, John</creator><general>American Association of Physicists in Medicine</general><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7X8</scope><scope>OTOTI</scope></search><sort><creationdate>201301</creationdate><title>The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?</title><author>Perisinakis, Kostas ; Seimenis, Ioannis ; Tzedakis, Antonis ; Papadakis, Antonios E. ; Damilakis, John</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c4212-47c969484da057c2a2a949e638f1d61d03c7b3b0e003d51df537e3eed92c7e0b3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2013</creationdate><topic>60 APPLIED LIFE SCIENCES</topic><topic>Adult</topic><topic>BLOOD FORMATION</topic><topic>bone</topic><topic>BONE MARROW</topic><topic>bow‐tie filter</topic><topic>BRAIN</topic><topic>Brain - diagnostic imaging</topic><topic>brain perfusion</topic><topic>CATARACTS</topic><topic>Computed tomography</topic><topic>COMPUTER CODES</topic><topic>Computerised tomographs</topic><topic>computerised tomography</topic><topic>COMPUTERIZED SIMULATION</topic><topic>COMPUTERIZED TOMOGRAPHY</topic><topic>deterministic effects</topic><topic>Digital computing or data processing equipment or methods, specially adapted for specific applications</topic><topic>Diseases</topic><topic>DOSIMETRY</topic><topic>Dosimetry/exposure assessment</topic><topic>ERYTHEMA</topic><topic>eye</topic><topic>filtering theory</topic><topic>HEAD</topic><topic>Head - anatomy & histology</topic><topic>HEALTH HAZARDS</topic><topic>Humans</topic><topic>Image data processing or generation, in general</topic><topic>IMAGE PROCESSING</topic><topic>Image scanners</topic><topic>Medical image noise</topic><topic>medical image processing</topic><topic>Medical image quality</topic><topic>Medical imaging</topic><topic>minimisation</topic><topic>misentering</topic><topic>MONTE CARLO METHOD</topic><topic>Monte Carlo methods</topic><topic>Monte Carlo simulations</topic><topic>Multislice</topic><topic>Numerical optimization</topic><topic>Organ Size</topic><topic>Organs at Risk - radiation effects</topic><topic>patient dose</topic><topic>Patient Positioning</topic><topic>PATIENTS</topic><topic>Perfusion Imaging - methods</topic><topic>PHANTOMS</topic><topic>Probability</topic><topic>Radiation Dosage</topic><topic>RADIATION DOSES</topic><topic>RADIATION PROTECTION AND DOSIMETRY</topic><topic>Radiation Tolerance</topic><topic>Radiometry</topic><topic>Risk</topic><topic>SIGNAL-TO-NOISE RATIO</topic><topic>SKELETON</topic><topic>SKIN</topic><topic>Software</topic><topic>Tissues</topic><topic>Tomography, X-Ray Computed - methods</topic><topic>X RADIATION</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Perisinakis, Kostas</creatorcontrib><creatorcontrib>Seimenis, Ioannis</creatorcontrib><creatorcontrib>Tzedakis, Antonis</creatorcontrib><creatorcontrib>Papadakis, Antonios E.</creatorcontrib><creatorcontrib>Damilakis, John</creatorcontrib><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>MEDLINE - Academic</collection><collection>OSTI.GOV</collection><jtitle>Medical physics (Lancaster)</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Perisinakis, Kostas</au><au>Seimenis, Ioannis</au><au>Tzedakis, Antonis</au><au>Papadakis, Antonios E.</au><au>Damilakis, John</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects?</atitle><jtitle>Medical physics (Lancaster)</jtitle><addtitle>Med Phys</addtitle><date>2013-01</date><risdate>2013</risdate><volume>40</volume><issue>1</issue><spage>011911</spage><epage>n/a</epage><pages>011911-n/a</pages><issn>0094-2405</issn><eissn>2473-4209</eissn><coden>MPHYA6</coden><abstract>Purpose:
To determine patient-specific absorbed peak doses to skin, eye lens, brain parenchyma, and cranial red bone marrow (RBM) of adult individuals subjected to low-dose brain perfusion CT studies on a 256-slice CT scanner, and investigate the effect of patient head size/shape, head position during the examination and bowtie filter used on peak tissue doses.
Methods:
The peak doses to eye lens, skin, brain, and RBM were measured in 106 individual-specific adult head phantoms subjected to the standard low-dose brain perfusion CT on a 256-slice CT scanner using a novel Monte Carlo simulation software dedicated for patient CT dosimetry. Peak tissue doses were compared to corresponding thresholds for induction of cataract, erythema, cerebrovascular disease, and depression of hematopoiesis, respectively. The effects of patient head size/shape, head position during acquisition and bowtie filter used on resulting peak patient tissue doses were investigated. The effect of eye-lens position in the scanned head region was also investigated. The effect of miscentering and use of narrow bowtie filter on image quality was assessed.
Results:
The mean peak doses to eye lens, skin, brain, and RBM were found to be 124, 120, 95, and 163 mGy, respectively. The effect of patient head size and shape on peak tissue doses was found to be minimal since maximum differences were less than 7%. Patient head miscentering and bowtie filter selection were found to have a considerable effect on peak tissue doses. The peak eye-lens dose saving achieved by elevating head by 4 cm with respect to isocenter and using a narrow wedge filter was found to approach 50%. When the eye lies outside of the primarily irradiated head region, the dose to eye lens was found to drop to less than 20% of the corresponding dose measured when the eye lens was located in the middle of the x-ray beam. Positioning head phantom off-isocenter by 4 cm and employing a narrow wedge filter results in a moderate reduction of signal-to-noise ratio mainly to the peripheral region of the phantom.
Conclusions:
Despite typical peak doses to skin, eye lens, brain, and RBM from the standard low-dose brain perfusion 256-slice CT protocol are well below the corresponding thresholds for the induction of erythema, cataract, cerebrovascular disease, and depression of hematopoiesis, respectively, every effort should be made toward optimization of the procedure and minimization of dose received by these tissues. The current study provides evidence that the use of the narrower bowtie filter available may considerably reduce peak absorbed dose to all above radiosensitive tissues with minimal deterioration in image quality. Considerable reduction in peak eye-lens dose may also be achieved by positioning patient head center a few centimeters above isocenter during the exposure.</abstract><cop>United States</cop><pub>American Association of Physicists in Medicine</pub><pmid>23298102</pmid><doi>10.1118/1.4773042</doi><tpages>8</tpages></addata></record> |
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| source | MEDLINE; Wiley Online Library Journals Frontfile Complete; Alma/SFX Local Collection |
| subjects | 60 APPLIED LIFE SCIENCES Adult BLOOD FORMATION bone BONE MARROW bow‐tie filter BRAIN Brain - diagnostic imaging brain perfusion CATARACTS Computed tomography COMPUTER CODES Computerised tomographs computerised tomography COMPUTERIZED SIMULATION COMPUTERIZED TOMOGRAPHY deterministic effects Digital computing or data processing equipment or methods, specially adapted for specific applications Diseases DOSIMETRY Dosimetry/exposure assessment ERYTHEMA eye filtering theory HEAD Head - anatomy & histology HEALTH HAZARDS Humans Image data processing or generation, in general IMAGE PROCESSING Image scanners Medical image noise medical image processing Medical image quality Medical imaging minimisation misentering MONTE CARLO METHOD Monte Carlo methods Monte Carlo simulations Multislice Numerical optimization Organ Size Organs at Risk - radiation effects patient dose Patient Positioning PATIENTS Perfusion Imaging - methods PHANTOMS Probability Radiation Dosage RADIATION DOSES RADIATION PROTECTION AND DOSIMETRY Radiation Tolerance Radiometry Risk SIGNAL-TO-NOISE RATIO SKELETON SKIN Software Tissues Tomography, X-Ray Computed - methods X RADIATION |
| title | The effect of head size/shape, miscentering, and bowtie filter on peak patient tissue doses from modern brain perfusion 256-slice CT: How can we minimize the risk for deterministic effects? |
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