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Edmund J, Feen Rønjom M, van Overeem Felter M, Maare C, Margrete Juul Dam A, Tsaggari E, Wohlfahrt P. Split-filter dual energy computed tomography radiotherapy: From calibration to image guidance. Phys Imaging Radiat Oncol 2023; 28:100495. [PMID: 37876826 PMCID: PMC10590838 DOI: 10.1016/j.phro.2023.100495] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 10/26/2023] Open
Abstract
Background and purpose Dual-energy computed tomography (DECT) is an emerging technology in radiotherapy (RT). Here, we investigate split-filter DECT throughout the RT treatment chain as compared to single-energy CT (SECT). Materials and methods DECT scans were acquired with a tin-gold split-filter at 140 kV resulting in a low- and high-energy CT reconstruction (recon). Ten cancer patients (four head-and-neck (HN), three rectum, two anal/pelvis and one abdomen) were DECT scanned without and with iodine administered. A cylindrical and an anthropomorphic HN phantom were scanned with DECT and 120 kV SECT. The DECT images generated were: 120 kV SECT-equivalent (CTmix), virtual monoenergetic images (VMIs), iodine map, virtual non-contrast (VNC), effective atomic number (Zeff), and relative electron density (ρe,w). The clinical utility of these recons was investigated for calibration, delineation, dose calculation and image-guided RT (IGRT). Results A calibration curve for 75 keV VMI had a root-mean-square-error (RMSE) of 34 HU in closest agreement with the RSME of SECT calibration. This correlated with a phantom-based dosimetric agreement to SECT of γ1%1mm > 98%. A 40 keV VMI recon was most promising to improve tumor delineation accuracy with an average evaluation score of 1.6 corresponding to "partial improvement". The dosimetric impact of iodine was in general < 2%. For this setup, VNC vs. non-contrast CTmix based dose calculations are considered equivalent. SECT- and DECT-based IGRT was in agreement within the setup uncertainty. Conclusions DECT-based RT could be a feasible alternative to SECT providing additional recons to support the different steps of the RT workflow.
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Affiliation(s)
- Jens Edmund
- Radiotherapy Research Unit, Department of Oncology, Herlev & Gentofte Hospital, Herlev, Denmark
- Niels Bohr Institute, Copenhagen University, Denmark
| | - Marianne Feen Rønjom
- Radiotherapy Research Unit, Department of Oncology, Herlev & Gentofte Hospital, Herlev, Denmark
| | | | - Christian Maare
- Radiotherapy Research Unit, Department of Oncology, Herlev & Gentofte Hospital, Herlev, Denmark
| | | | - Eirini Tsaggari
- Radiotherapy Research Unit, Department of Oncology, Herlev & Gentofte Hospital, Herlev, Denmark
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The Effect of Contrast-enhanced Computed Tomography (CT) Scans on the Calculated Dose of Radiotherapy in a Thorax Phantom. INTERNATIONAL JOURNAL OF CANCER MANAGEMENT 2021. [DOI: 10.5812/ijcm.84158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: Despite the benefits of contrast-enhanced computed tomography (CT) scans in better tumor volume delineation, it can affect the accuracy of dose calculation in radiation therapy. This study examined this effect on a thorax phantom. Objectives: The influence of different variables including the concentrations of the Visipaque contrast media, tumor sizes, and CT scan energies on the dose measurement was examined. Methods: Transparent cylinders containing the contrast media were inserted in the lung area of the phantom and the CT scans were made. Non-enhanced CT scans were also acquired. Treatment planning using 2 opposite fields was performed on the CT scans and the doses were calculated in the treatment planning system. The results of the 2 sets of enhanced and non-enhanced CT scans were compared. Results: The correlation between concentration and the percentage of mean dose of the tumor volume was significant in 2 of the tumor sizes. The differences in the mean doses of the 2 plans were examined and more than 3% increase was observed in higher concentrations of the contrast media. Conclusions: According to this study, the suitable concentration of the contrast media administered and the CT scan energy should be considered. This would help to decrease the discrepancies between the calculated and delivered dose in radiotherapy treatments to a clinically acceptable level. The importance of time delays for CT scans after administration of the contrast media is emphasized.
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Kamal R, Thaper D, Kumar R, Singh G, Yadav HP, Oinam AS, Kumar V, Sharma H. Dosimetric impact of contrast-enhanced 4d computed tomography for stereotactic body radiation therapy of hepatocelluar carcinoma. Rep Pract Oncol Radiother 2021; 26:598-604. [PMID: 34434576 PMCID: PMC8382070 DOI: 10.5603/rpor.a2021.0075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/27/2021] [Indexed: 05/08/2023] Open
Abstract
BACKGROUND A purpose of the study was to investigate the dosimetric impact of contrast media on dose calculation using average 4D contrast-enhanced computed tomography (4D-CECT) and delayed 4D-CT (d4D-CT) images caused by CT simulation contrast agents for stereotactic body radiation therapy (SBRT) of liver cases. MATERIALS AND METHODS Fifteen patients of liver SBRT treated using the volumetric modulated arc therapy (VMAT) technique were selected retrospectively. 4D-CECT, and d4D-CT were acquired with the Anzai gating system and GE CT. For all patients, gross target volume (GTV) was contoured on the ten phases after rigid registration of both the contrast and delayed scans and merged to generate internal target volume (ITV) on average CT images. Region of interest (ROI) was drawn on contrast images and then copied to the delayed images after rigid registration of two average CT datasets. The treatment plans were generated for contrast enhanced average CT, delayed average CT and contrast enhanced average CT with electron density of the heart overridden. RESULTS No significant dosimetric difference was observed in plans parameters (mean HU value of the liver, total monitor units, total control points, degree of modulation and average segment area) except mean HU value of the aorta amongst the three arms. All the OARs were evaluated and resulted in statistically insignificant variation (p > 0.05) using one way ANOVA analysis. CONCLUSIONS Contrast enhanced 4D-CT is advantageous in accurate delineation of tumors and assessing accurate ITV. The treatment plans generated on average 4D-CECT and average d4D-CT have a clinically insignificant effect on dosimetric parameters.
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Affiliation(s)
- Rose Kamal
- Centre for Medical Physics, Panjab University, Chandigarh, India
- Department of Radiation Oncology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Deepak Thaper
- Centre for Medical Physics, Panjab University, Chandigarh, India
- Department of Radiation Oncology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Rishabh Kumar
- Centre for Medical Physics, Panjab University, Chandigarh, India
| | - Gaganpreet Singh
- Centre for Medical Physics, Panjab University, Chandigarh, India
- Department of Radiotherapy, Post Graduate Institute of Medical Education and Research, Regional Cancer Centre, Chandigarh, India
| | - Hanuman P. Yadav
- Department of Radiation Oncology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Arun S. Oinam
- Department of Radiotherapy, Post Graduate Institute of Medical Education and Research, Regional Cancer Centre, Chandigarh, India
| | - Vivek Kumar
- Centre for Medical Physics, Panjab University, Chandigarh, India
| | - Hitesh Sharma
- Govt. Cancer Hospital, NSCB Medical College, Jabalpur, Madhya Pradesh, India
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Oral contrast agents lead to underestimation of dose calculation in volumetric-modulated arc therapy planning for pelvic irradiation. Chin Med J (Engl) 2020; 133:2061-2070. [PMID: 32810050 PMCID: PMC7478501 DOI: 10.1097/cm9.0000000000001025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Supplemental Digital Content is available in the text Background The effects of oral contrast agents (OCAs) on dosimetry have not been studied in detail. Therefore, this study aimed to examine the influence of OCAs on dose calculation in volumetric-modulated arc therapy plans for rectal cancer. Methods From 2008 to 2016, computed tomography (CT) images were obtained from 33 rectal cancer patients administered OCA with or without intravenous contrast agent (ICA) and 14 patients who received no contrast agent. CT numbers of organs at risk were recorded and converted to electronic densities. Volumetric-modulated arc therapy plans were designed before and after the original densities were replaced with non-enhanced densities. Doses to the planned target volume (PTV) and organs at risk were compared between the plans. Results OCA significantly increased the mean and maximum densities of the bowels, while the effects of ICA on these parameters depended on the blood supply of the organs. With OCA, the actual doses for PTV were significantly higher than planned and doses to the bowel increased significantly although moderately. However, the increase in the volume receiving a high-range doses was substantial (the absolute change of intestine volume receiving ≥52 Gy: 1.46 [0.05−3.99, cubic centimeter range: −6.74 to 128.12], the absolute change of colon volume receiving ≥50 Gy: 0.34 [0.01−1.53 cc, range: −0.08 to 3.80 cc]. Dose changes due to ICA were insignificant. Pearson correlation showed that dose changes were significantly correlated with a high intestinal volume within or near the PTV (ρ > 0.5, P < 0.05) and with the density of enhanced intestine (ρ > 0.3, P < 0.05). Conclusions Contrast agents applied in simulation cause underestimation of doses in actual treatment. The overdose due to ICA was slight, while that due to OCA was moderate. The bowel volume receiving ≥50Gy was dramatically increased when OCA within the bowel was absent. Physicians should be aware of these issues if the original plan is barely within clinical tolerance or if a considerable volume of enhanced intestine is within or near the PTV.
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Komiyama R, Ohira S, Kanayama N, Karino T, Washio H, Ueda Y, Miyazaki M, Teshima T. Volumetric modulated arc therapy treatment planning based on virtual monochromatic images for head and neck cancer: effect of the contrast-enhanced agent on dose distribution. J Appl Clin Med Phys 2019; 20:144-152. [PMID: 31633869 PMCID: PMC6839366 DOI: 10.1002/acm2.12752] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/01/2019] [Accepted: 09/24/2019] [Indexed: 12/14/2022] Open
Abstract
Virtual monochromatic images (VMIs) at a lower energy level can improve image quality but the computed tomography (CT) number of iodine contained in the contrast‐enhanced agent is dramatically increased. We assessed the effect of the use of contrast‐enhanced agent on the dose distributions in volumetric modulated arc therapy (VMAT) planning for head and neck cancer (HNC). Based on the VMIs at 40 keV (VMI40keV), 60 keV(VMI60keV), and 77 keV (VMI77keV) of a tissue characterization phantom, lookup tables (LUTs) were created. VMAT plans were generated for 15 HNC patients based on contrast‐enhanced‐ (CE‐) VMIs at 40‐, 60‐, and 77 keV using the corresponding LUTs, and the doses were recalculated based on the noncontrast‐enhanced‐ (nCE‐) VMIs. For all structures, the difference in CT numbers owing to the contrast‐enhanced agent was prominent as the energy level of the VMI decreased, and the mean differences in CT number between CE‐ and nCE‐VMI was the largest for the clinical target volume (CTV) (125.3, 55.9, and 33.1 HU for VMI40keV, VMI60keV, and VMI77keV, respectively). The mean difference of the dosimetric parameters (D99%, D50%, D1%, Dmean, and D0.1cc) for CTV and OARs was <1% in the treatment plans based on all VMIs. The maximum difference was observed for CTV in VMI40keV (2.4%), VMI60keV (1.9%), and VMI77keV (1.5%) plans. The effect of the contrast‐enhanced agent was larger in the VMAT plans based on the VMI at a lower energy level for HNC patients. This effect is not desirable in a treatment planning procedure.
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Affiliation(s)
- Riho Komiyama
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Shingo Ohira
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan.,Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan
| | - Naoyuki Kanayama
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Tsukasa Karino
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Hayate Washio
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Yoshihiro Ueda
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Masayoshi Miyazaki
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Teruki Teshima
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
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Ahmad SB, Paudel MR, Sarfehnia A, Kim A, Pang G, Ruschin M, Sahgal A, Keller BM. The dosimetric impact of gadolinium-based contrast media in GBM brain patient plans for a MRI-Linac. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1361-6560/aa7acb] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Heydarheydari S, Farshchian N, Haghparast A. Influence of the contrast agents on treatment planning dose calculations of prostate and rectal cancers. Rep Pract Oncol Radiother 2016; 21:441-6. [PMID: 27489514 DOI: 10.1016/j.rpor.2016.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/07/2016] [Accepted: 04/13/2016] [Indexed: 01/22/2023] Open
Abstract
AIM The aim of the present study is to quantify differences in dose calculations caused by using CA and determine if the resulting differences are clinically significant. BACKGROUND The influence of contrast agents (CA) on radiation dose calculations must be taken into account in treatment planning. MATERIALS AND METHODS Eleven patients with pelvic cancers were included in this study and two sets of CTs were taken for each patient (without and with CA) in the same position and coordinates. Both sets of images were transferred to the DosiSoft ISOgray treatment planning system for contouring and calculating the dose distribution and monitor units (MUs) with Collapsed Cone and Superposition algorithms, respectively. All plans were generated on pre-contrast CT and subsequently copied to the post-contrast CT. Radiation dose calculations from the two sets of CTs were compared using a paired sample t-test. RESULTS The results showed a statistically insignificant difference between pre- and post-contrast CT treatment plans for target volume and OARs (p > 0.05), except bladder organ in the prostate region (p < 0.05) but the relative mean dose and MU differences were less than 2% in any patient for 18 MV photon beam. CONCLUSIONS Treatment planning on contrasted images generally showed a lower radiation dose to both target volume and OARs than plans on non-contrasted images. The results of this research showed that the small radiation dose differences between the plans for the CT scans with and without CA seem to be clinically insignificant; therefore, contrast-enhanced CT can be used for both target delineation and treatment planning of prostate and rectal cancers.
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Affiliation(s)
- Sahel Heydarheydari
- Department of Biomedical Physics and Engineering, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Negin Farshchian
- Department of Radiation Oncology, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Abbas Haghparast
- Department of Biomedical Physics and Engineering, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Yamada S, Ueguchi T, Ogata T, Mizuno H, Ogihara R, Koizumi M, Shimazu T, Murase K, Ogawa K. Radiotherapy treatment planning with contrast-enhanced computed tomography: feasibility of dual-energy virtual unenhanced imaging for improved dose calculations. Radiat Oncol 2014; 9:168. [PMID: 25070169 PMCID: PMC4118618 DOI: 10.1186/1748-717x-9-168] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 07/22/2014] [Indexed: 11/10/2022] Open
Abstract
Background In radiotherapy treatment planning, intravenous administration of an iodine-based contrast agent during computed tomography (CT) improves the accuracy of delineating target volumes. However, increased tissue attenuation resulting from the high atomic number of iodine may result in erroneous dose calculations because the contrast agent is absent during the actual procedure. The purpose of this proof-of-concept study was to present a novel framework to improve the accuracy of dose calculations using dual-energy virtual unenhanced CT in the presence of an iodine-based contrast agent. Methods Simple phantom experiments were designed to assess the feasibility of the proposed concept. By utilizing a “second-generation” dual-source CT scanner equipped with a tin filter for improved spectral separation, four CT datasets were obtained using both a water phantom and an iodine phantom: “true unenhanced” images with attenuation values of 2 ± 11 Hounsfield Units (HU), “enhanced” images with attenuation values of 274 ± 23 HU, and two series of “virtual unenhanced” images synthesized from dual-energy scans of the iodine phantom, each with a different combination of tube voltages. Two series of virtual unenhanced images demonstrated attenuation values of 12 ± 29 HU (with 80 kVp/140 kVp) and 34 ± 10 HU (with 100 kVp/140 kVp) after removing the iodine component from the contrast-enhanced images. Dose distributions of the single photon beams calculated from the enhanced images and two series of virtual unenhanced images were compared to those from true unenhanced images as a reference. Results The dose distributions obtained from both series of virtual unenhanced images were almost equivalent to that from the true unenhanced images, whereas the dose distribution obtained from the enhanced images indicated increased beam attenuation caused by the high attenuation characteristics of iodine. Compared to the reference dose distribution from the true unenhanced images, the dose distribution pass rates from both series of virtual unenhanced images were greater than 90%, while those from the enhanced images were less than approximately 50–60%. Conclusions Dual-energy virtual unenhanced CT improves the accuracy of dose distributions in radiotherapy treatment planning by removing the iodine component from contrast-enhanced images.
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Affiliation(s)
- Sachiko Yamada
- Department of Radiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Dosimetric effects of bladder and rectal contrast agents in prostate radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2013. [DOI: 10.1017/s1460396912000428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractBackground and purposeAccurate delineation of the target volume and organs at risk (OARs) are vital to ensure systematic errors are small. The use of contrast agents (CAs) in the bladder and rectum may aid contouring and reduce inter and intra-observer variability. The aim of this study was to evaluate the dosimetric effect of the presence of such contrast on the monitor units (MUs), planning target volume (PTV), rectum and bladder.Materials and methodsThe prostate, seminal vesicles, rectum and bladder were contoured by a single observer on ten patients with bladder and rectal contrast. To evaluate the dosimetric effect of the presence of contrast, the density of the ten patients with contrast in the bladder and rectum was virtually changed to 1 g/cm3. A four-field 15 MV conformal radiation therapy technique was applied in which dose volume histograms and MUs were compared using computed tomographic (CT) density and the 1 g/cm3density.ResultsThe presence of contrast resulted in a 0·09% (<1 MU) increase in anterior MUs and decrease of 1% (<1 MU) in the posterior beam MUs. Lateral beams were not affected. The PTV and bladder dose increased slightly without contrast. The rectum showed a maximum change of 0·62% dose among the measured dose values. A maximum dose of 0·3 Gy at the 30% volume was also seen.ConclusionsThe dosimetric effect of bladder and rectal CAs on MUs, dose to the PTV and OARs in using this technique was very small. This would not be clinically significant, but only if the extreme limits of dose volume constraints were being reached.
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Kim HJ, Chang AR, Park YK, Ye SJ. Dosimetric effect of CT contrast agent in CyberKnife treatment plans. Radiat Oncol 2013; 8:244. [PMID: 24139405 PMCID: PMC3829371 DOI: 10.1186/1748-717x-8-244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 09/22/2013] [Indexed: 11/18/2022] Open
Abstract
Background To investigate the effect of computed tomography (CT) contrast enhancement (CE) on the 3D dose distributions of non-coplanar small field beams in the CyberKnife (CK) treatment planning system (TPS) for the stereotactic ablative radiotherapy (SABR). Methods Twenty-two pre-CE CT treatment plans were recruited to this retrospective plan study. Their post-CE CT plans were based on the pre-CE CT plan data and calculated using the same MU and beam paths in either Ray-Tracing or Monte Carlo (MC) algorithms. The differences in the doses of the beam path and the reference point between the pre- and post-CE CT plans were compared. The minimum, maximum, and mean doses in dose-volume histograms (DVHs) of target and organs-at-risk (OARs) were also compared. Results The dose differences between the pre- and post-CE plans in a single beam path were less than 1.05% in both calculation algorithms, with respect to the prescription dose. At the center of the target volume, it was 1.9% (maximum 6.2%) in Ray-Tracing and 1.6% (maximum 4.0%) in MC. The CA effect showed on average 1.2% difference in the OAR maximum dose (maximum 7.8% in Ray-Tracing and 7.2% in MC). In the lung cases, the CT CE resulted in a dose difference of 2.4% (from 1.0% to 6.5%) without the calculation algorithm effect (maximum 20.3%). Conclusions The CK treatment plan using the post-CE CT generally afforded less than 2% dose differences from the pre-CE CT plan. However, it could be up to 7.8% depending on the target positions in a body and be more than 20% with the calculation algorithms. Thus, the post-CE CT in CK treatment plans should be used with careful consideration for the CA effect, target position, and calculation algorithm factors.
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Affiliation(s)
| | | | | | - Sung-Joon Ye
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, South Korea.
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Li HS, Chen JH, Zhang W, Shang DP, Li BS, Sun T, Lin XT, Yin Y. Influence of intravenous contrast medium on dose calculation using CT in treatment planning for oesophageal cancer. Asian Pac J Cancer Prev 2013; 14:1609-14. [PMID: 23679244 DOI: 10.7314/apjcp.2013.14.3.1609] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE To evaluate the effect of intravenous contrast on dose calculation in radiation treatment planning for oesophageal cancer. METHODS A total of 22 intravein-contrasted patients with oesophageal cancer were included. The Hounsfield unit (HU) value of the enhanced blood stream in thoracic great vessels and heart was overridden with 45 HU to simulate the non-contrast CT image, and 145 HU, 245 HU, 345 HU, and 445 HU to model the different contrast-enhanced scenarios. 1000 HU and -1000 HU were used to evaluate two non-physiologic extreme scenarios. Variation in dose distribution of the different scenarios was calculated to quantify the effect of contrast enhancement. RESULTS In the contrast-enhanced scenarios, the mean variation in dose for planning target volume (PTV) was less than 1.0%, and those for the total lung and spinal cord were less than 0.5%. When the HU value of the blood stream exceeded 245 the average variation exceeded 1.0% for the heart V40. In the non-physiologic extreme scenarios, the dose variationof PTV was less than 1.0%, while the dose calculations of the organs at risk were greater than 2.0%. CONCLUSIONS The use of contrast agent does not significantly influence dose calculation of PTV, lung and spinal cord. However, it does have influence on dose accuracy for heart.
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Affiliation(s)
- Hong-Sheng Li
- Department of Radiation Oncology, Cancer Hospital and Institute, Tianjin Medical University, Tianjin, China.
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Intravenous Contrast Agent Influence on Thoracic Computed Tomography Simulation Investigated Through A Heterogeneous Dose Calculation Method Using 5-Bulk Densities. Am J Clin Oncol 2012; 35:110-4. [DOI: 10.1097/coc.0b013e318209a910] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Hwang UJ, Shin DH, Kim TH, Moon SH, Lim YK, Jeong H, Rah JE, Kim SS, Kim JY, Kim DY, Park SY, Cho KH. The Effect of a Contrast Agent on Proton Beam Range in Radiotherapy Planning Using Computed Tomography for Patients With Locoregionally Advanced Lung Cancer. Int J Radiat Oncol Biol Phys 2011; 81:e317-24. [DOI: 10.1016/j.ijrobp.2011.02.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Revised: 02/06/2011] [Accepted: 02/09/2011] [Indexed: 10/18/2022]
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Stern RL, Heaton R, Fraser MW, Goddu SM, Kirby TH, Lam KL, Molineu A, Zhu TC. Verification of monitor unit calculations for non-IMRT clinical radiotherapy: report of AAPM Task Group 114. Med Phys 2011; 38:504-30. [PMID: 21361219 DOI: 10.1118/1.3521473] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The requirement of an independent verification of the monitor units (MU) or time calculated to deliver the prescribed dose to a patient has been a mainstay of radiation oncology quality assurance. The need for and value of such a verification was obvious when calculations were performed by hand using look-up tables, and the verification was achieved by a second person independently repeating the calculation. However, in a modern clinic using CT/MR/PET simulation, computerized 3D treatment planning, heterogeneity corrections, and complex calculation algorithms such as convolution/superposition and Monte Carlo, the purpose of and methodology for the MU verification have come into question. In addition, since the verification is often performed using a simpler geometrical model and calculation algorithm than the primary calculation, exact or almost exact agreement between the two can no longer be expected. Guidelines are needed to help the physicist set clinically reasonable action levels for agreement. This report addresses the following charges of the task group: (1) To re-evaluate the purpose and methods of the "independent second check" for monitor unit calculations for non-IMRT radiation treatment in light of the complexities of modern-day treatment planning. (2) To present recommendations on how to perform verification of monitor unit calculations in a modern clinic. (3) To provide recommendations on establishing action levels for agreement between primary calculations and verification, and to provide guidance in addressing discrepancies outside the action levels. These recommendations are to be used as guidelines only and shall not be interpreted as requirements.
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Affiliation(s)
- Robin L Stern
- Department of Radiation Oncology, University of California, Davis, Sacramento, California 95817, USA.
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Xiao J, Zhang H, Gong Y, Fu Y, Tang B, Wang S, Jiang Q, Li P. Feasibility of using intravenous contrast-enhanced computed tomography (CT) scans in lung cancer treatment planning. Radiother Oncol 2010; 96:73-7. [PMID: 20347496 DOI: 10.1016/j.radonc.2010.02.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 02/16/2010] [Accepted: 02/21/2010] [Indexed: 11/27/2022]
Affiliation(s)
- Jianghong Xiao
- Radiation Physics Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, PR China
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The effect of intravenous contrast on photon radiation therapy dose calculations for lung cancer. Am J Clin Oncol 2010; 33:153-6. [PMID: 19806038 DOI: 10.1097/coc.0b013e3181a44637] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the effect of intravenous contrast-enhanced computed tomography (CT) scans on the photon radiation dose calculations for lung cancer treatment planning. MATERIALS AND METHODS Nonionic iodinated intravenous contrast (Iohexol) was administered during the treatment planning CT scan of 9 patients with node-positive non-small-cell lung cancer (NSCLC). The potential effect of intravenous contrast was studied by changing the density of the contrast-enhanced vessels. A total of 9 patients were treated in this study: 5 patients with intensity-modulated radiation therapy (IMRT), and 4 patients with three-dimensional (3D) conformal radiation therapy. A treatment plan was generated from an unmanipulated "normal contrast" planning scan. The same planning parameters were then applied to a "no contrast" planning scan. The effect of intravenous contrast was quantified by calculating the percent change of dose in a variety of target and normal structures. To evaluate a worst-case scenario, the comparison between "normal contrast" and "no contrast" planning scans was repeated, assigning each vessel the artificial high density of 1.3 g/cm. RESULTS Dose differences between the planning image set using intravenous contrast and the image set without contrast were less than 2.5% for planning target volumes. A worst-case scenario in which normal contrast was overridden with an artificially high density of 1.3 g/cm led to small dose differences of less than 3%. CONCLUSIONS Planning lung radiation therapy treatment using CT scans that contain intravenous contrast does not result in clinically significant errors in dose delivery.
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Kim S, Russell W, Price P, Saleem A. Suboptimal use of intravenous contrast during radiotherapy planning in the UK. Br J Radiol 2008; 81:963-9. [PMID: 18762482 DOI: 10.1259/bjr/24432468] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
We aimed to evaluate the use of intravenous (IV) contrast during acquisition of radiotherapy planning (RTP) scans and to compare current usage with the Royal College of Radiologists' (RCR) recommendations. Questionnaires were circulated via the Academic Clinical Oncology and Radiobiology Research Network (ACORRN) website, email and post to 60 UK radiotherapy centre managers. Questions were asked regarding the (i) tumour sites where IV contrast was used, (ii) person administering the contrast, (iii) availability of dynamic pump, (iv) tumour sites that centres wished to use contrast, (v) reasons for not using contrast and (vi) awareness of RCR recommendations. 50 (83%) centres responded to the questionnaire, of which 27 responded via the ACCORN website and 18 by e-mail. Despite 38 out of 50 responding centres using IV contrast, and accessibility to dynamic pumps existing in 39 centres, IV contrast usage was suboptimal, with more than half of the centres (27/50; 54%) wishing to use it at more tumour sites. IV contrast was most often used during RTP of the brain, with suboptimal usage in lung tumours. None of the 50 centres administered IV contrast during RTP scan acquisition in all of the 8 RCR recommended tumour sites. Radiographers were mainly responsible for contrast administration, and a lack of staff was cited as the main reason for suboptimal contrast usage. Disappointingly, only 35 of the 50 radiotherapy managers (70%) were aware of the RCR recommendations. Redress of the underlying reasons for suboptimal IV contrast administration during RTP, including acquisition of the necessary skill mix by staff and implementation of RCR recommendations, would help standardize UK practice.
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Affiliation(s)
- S Kim
- Department of Clinical Oncology, Christie Hospital, Manchester, UK
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Shibamoto Y, Naruse A, Fukuma H, Ayakawa S, Sugie C, Tomita N. Influence of contrast materials on dose calculation in radiotherapy planning using computed tomography for tumors at various anatomical regions: a prospective study. Radiother Oncol 2007; 84:52-5. [PMID: 17532496 DOI: 10.1016/j.radonc.2007.05.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 05/14/2007] [Accepted: 05/14/2007] [Indexed: 11/23/2022]
Abstract
Influences of iodinated contrast media on dose calculation were studied in 26 patients. Mean increases in monitor units by contrast media administration were less than 1% and considered negligible in planning of whole-brain, whole-neck, mediastinal, and whole-pelvic irradiation. However, mean increases over 2% were seen in planning of upper-abdominal radiotherapy.
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Affiliation(s)
- Yuta Shibamoto
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
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