Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy
Abstract Background To evaluate the effect of pretreatment megavoltage computed tomographic (MVCT) scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy. Methods Both anthropomorphic heterogeneous chest and pelvic phantoms were planned with virtual targets by To...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2018-04-01
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| Series: | Radiation Oncology |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13014-018-0989-y |
| _version_ | 1818273123414310912 |
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| author | Jian Zhu Tong Bai Jiabing Gu Ziwen Sun Yumei Wei Baosheng Li Yong Yin |
| author_facet | Jian Zhu Tong Bai Jiabing Gu Ziwen Sun Yumei Wei Baosheng Li Yong Yin |
| author_sort | Jian Zhu |
| collection | DOAJ |
| description | Abstract Background To evaluate the effect of pretreatment megavoltage computed tomographic (MVCT) scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy. Methods Both anthropomorphic heterogeneous chest and pelvic phantoms were planned with virtual targets by TomoTherapy Physicist Station and were scanned with TomoTherapy megavoltage image-guided radiotherapy (IGRT) system consisted of six groups of options: three different acquisition pitches (APs) of ‘fine’, ‘normal’ and ‘coarse’ were implemented by multiplying 2 different corresponding reconstruction intervals (RIs). In order to mimic patient setup variations, each phantom was shifted 5 mm away manually in three orthogonal directions respectively. The effect of MVCT scan options was analyzed in image quality (CT number and noise), adaptive dose calculation deviations and positional correction variations. Results MVCT scanning time with pitch of ‘fine’ was approximately twice of ‘normal’ and 3 times more than ‘coarse’ setting, all which will not be affected by different RIs. MVCT with different APs delivered almost identical CT numbers and image noise inside 7 selected regions with various densities. DVH curves from adaptive dose calculation with serial MVCT images acquired by varied pitches overlapped together, where as there are no significant difference in all p values of intercept & slope of emulational spinal cord (p = 0.761 & 0.277), heart (p = 0.984 & 0.978), lungs (p = 0.992 & 0.980), soft tissue (p = 0.319 & 0.951) and bony structures (p = 0.960 & 0.929) between the most elaborated and the roughest serials of MVCT. Furthermore, gamma index analysis shown that, compared to the dose distribution calculated on MVCT of ‘fine’, only 0.2% or 1.1% of the points analyzed on MVCT of ‘normal’ or ‘coarse’ do not meet the defined gamma criterion. On chest phantom, all registration errors larger than 1 mm appeared at superior-inferior axis, which cannot be avoided with the smallest AP and RI. On pelvic phantom, craniocaudal errors are much smaller than chest, however, AP of ‘coarse’ presents larger registration errors which can be reduced from 2.90 mm to 0.22 mm by registration technique of ‘full image’. Conclusions AP of ‘coarse’ with RI of 6 mm is recommended in adaptive radiotherapy (ART) planning to provide craniocaudal longer and faster MVCT scan, while registration technique of ‘full image’ should be used to avoid large residual error. Considering the trade-off between IGRT and ART, AP of ‘normal’ with RI of 2 mm was highly recommended in daily practice. |
| first_indexed | 2024-12-12T21:52:57Z |
| format | Article |
| id | doaj.art-d6a49785ac6446f8b75a335af819618f |
| institution | Directory Open Access Journal |
| issn | 1748-717X |
| language | English |
| last_indexed | 2024-12-12T21:52:57Z |
| publishDate | 2018-04-01 |
| publisher | BMC |
| record_format | Article |
| series | Radiation Oncology |
| spelling | doaj.art-d6a49785ac6446f8b75a335af819618f2022-12-22T00:10:45ZengBMCRadiation Oncology1748-717X2018-04-0113111110.1186/s13014-018-0989-yEffects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapyJian Zhu0Tong Bai1Jiabing Gu2Ziwen Sun3Yumei Wei4Baosheng Li5Yong Yin6Department of Radiation Oncology, Shandong Cancer Hospital and InstituteDepartment of Radiation Oncology, Shandong Cancer Hospital and InstituteDepartment of Radiation Oncology, Shandong Cancer Hospital and InstituteMedical Department, Affiliated Hospital of Shandong Academy of Medical SciencesDepartment of Radiation Oncology, Shandong Cancer Hospital and InstituteDepartment of Radiation Oncology, Shandong Cancer Hospital and InstituteDepartment of Radiation Oncology, Shandong Cancer Hospital and InstituteAbstract Background To evaluate the effect of pretreatment megavoltage computed tomographic (MVCT) scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy. Methods Both anthropomorphic heterogeneous chest and pelvic phantoms were planned with virtual targets by TomoTherapy Physicist Station and were scanned with TomoTherapy megavoltage image-guided radiotherapy (IGRT) system consisted of six groups of options: three different acquisition pitches (APs) of ‘fine’, ‘normal’ and ‘coarse’ were implemented by multiplying 2 different corresponding reconstruction intervals (RIs). In order to mimic patient setup variations, each phantom was shifted 5 mm away manually in three orthogonal directions respectively. The effect of MVCT scan options was analyzed in image quality (CT number and noise), adaptive dose calculation deviations and positional correction variations. Results MVCT scanning time with pitch of ‘fine’ was approximately twice of ‘normal’ and 3 times more than ‘coarse’ setting, all which will not be affected by different RIs. MVCT with different APs delivered almost identical CT numbers and image noise inside 7 selected regions with various densities. DVH curves from adaptive dose calculation with serial MVCT images acquired by varied pitches overlapped together, where as there are no significant difference in all p values of intercept & slope of emulational spinal cord (p = 0.761 & 0.277), heart (p = 0.984 & 0.978), lungs (p = 0.992 & 0.980), soft tissue (p = 0.319 & 0.951) and bony structures (p = 0.960 & 0.929) between the most elaborated and the roughest serials of MVCT. Furthermore, gamma index analysis shown that, compared to the dose distribution calculated on MVCT of ‘fine’, only 0.2% or 1.1% of the points analyzed on MVCT of ‘normal’ or ‘coarse’ do not meet the defined gamma criterion. On chest phantom, all registration errors larger than 1 mm appeared at superior-inferior axis, which cannot be avoided with the smallest AP and RI. On pelvic phantom, craniocaudal errors are much smaller than chest, however, AP of ‘coarse’ presents larger registration errors which can be reduced from 2.90 mm to 0.22 mm by registration technique of ‘full image’. Conclusions AP of ‘coarse’ with RI of 6 mm is recommended in adaptive radiotherapy (ART) planning to provide craniocaudal longer and faster MVCT scan, while registration technique of ‘full image’ should be used to avoid large residual error. Considering the trade-off between IGRT and ART, AP of ‘normal’ with RI of 2 mm was highly recommended in daily practice.http://link.springer.com/article/10.1186/s13014-018-0989-yTomoTherapyMegavoltage computed tomographicImage-guided radiotherapyAdaptive radiotherapy |
| spellingShingle | Jian Zhu Tong Bai Jiabing Gu Ziwen Sun Yumei Wei Baosheng Li Yong Yin Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy Radiation Oncology TomoTherapy Megavoltage computed tomographic Image-guided radiotherapy Adaptive radiotherapy |
| title | Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy |
| title_full | Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy |
| title_fullStr | Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy |
| title_full_unstemmed | Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy |
| title_short | Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy |
| title_sort | effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical tomotherapy |
| topic | TomoTherapy Megavoltage computed tomographic Image-guided radiotherapy Adaptive radiotherapy |
| url | http://link.springer.com/article/10.1186/s13014-018-0989-y |
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