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Cumur C, Fujibuchi T, Arakawa H, Hamada K. Dose estimation for cone-beam computed tomography in image-guided radiation therapy for pelvic cancer using adult mesh-type reference computational phantoms. Radiol Phys Technol 2023; 16:203-211. [PMID: 36877400 DOI: 10.1007/s12194-023-00708-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 02/24/2023] [Accepted: 02/24/2023] [Indexed: 03/07/2023]
Abstract
The use of cone-beam computed tomography (CBCT) is expanding owing to its installation in linear accelerators for radiation therapy, and the imaging dose induced by this system has become the center of attention. Here, the dose to patients caused by the CBCT imager was investigated. Organ doses and effective doses for male and female mesh-type reference computational phantoms (MRCPs) and pelvis CBCT mode, routinely used for pelvic irradiation, were estimated using the Particle and Heavy Ion Transport Code System. The simulation results were confirmed based on the point-dose measurements. The estimated organ doses for male MRCPs with/without raised arms and for female MRCPs with/without raised arms were 0.00286-35.6 mGy, 0.00286-35.1 mGy, 0.00933-39.5 mGy, and 0.00931-39.0 mGy, respectively. The anticipated effective doses for male MRCPs with/without raised arms and female MRCPs with/without raised arms irradiated by pelvis CBCT mode were 4.25 mSv, 4.16 mSv, 7.66 mSv, and 7.48 mSv, respectively. The results of this study will be useful for patients who undergo image-guided radiotherapy with CBCT. However, because this study only covered one type of cancer with one type of imager, and image quality was not considered, more studies should be conducted to estimate the radiation dose from imaging devices in radiation therapy.
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Affiliation(s)
- Ceyda Cumur
- Graduate School of Medical Sciences, Division of Medical Quantum Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan.
| | - Toshioh Fujibuchi
- Faculty of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Hiroyuki Arakawa
- Faculty of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan
| | - Keisuke Hamada
- Department of Radiological Technology, National Hospital Organization Kyushu Cancer Center, 3-1-1, Notame Minami-Ku, Fukuoka, 811-1395, Japan
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Abuhaimed A, Martin CJ. Assessment of organ and size-specific effective doses from cone beam CT (CBCT) in image-guided radiotherapy (IGRT) based on body mass index (BMI). Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2023.110889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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Martin CJ, Abuhaimed A. Variations in size-specific effective dose with patient stature and beam width for kV cone beam CT imaging in radiotherapy. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2022; 42:031512. [PMID: 35917802 DOI: 10.1088/1361-6498/ac85fa] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
The facilities now available on linear accelerators for external beam radiotherapy enable radiation fields to be conformed to the shapes of tumours with a high level of precision. However, in order for the treatment delivered to take advantage of this, the patient must be positioned on the couch with the same degree of accuracy. Kilovoltage cone beam computed tomography systems are now incorporated into radiotherapy linear accelerators to allow imaging to be performed at the time of treatment, and image-guided radiation therapy is now standard in most radiotherapy departments throughout the world. However, because doses from imaging are much lower than therapy doses, less effort has been put into optimising radiological protection of imaging protocols. Standard imaging protocols supplied by the equipment vendor are often used with little adaptation to the stature of individual patients, and exposure factors and field sizes are frequently larger than necessary. In this study, the impact of using standard protocols for imaging anatomical phantoms of varying size from a library of 193 adult phantoms has been evaluated. Monte Carlo simulations were used to calculate doses for organs and tissues for each phantom, and results combined in terms of size-specific effective dose (SED). Values of SED from pelvic scans ranged from 11 mSv to 22 mSv for male phantoms and 8 mSv to 18 mSv for female phantoms, and for chest scans from 3.8 mSv to 7.6 mSv for male phantoms and 4.6 mSv to 9.5 mSv for female phantoms. Analysis of the results showed that if the same exposure parameters and field sizes are used, a person who is 5 cm shorter will receive a size SED that is 3%-10% greater, while a person who is 10 kg lighter will receive a dose that is 10%-14% greater compared with the average size.
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Affiliation(s)
- C J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Gartnavel Royal Hospital, Glasgow G12 0XH, United Kingdom
| | - A Abuhaimed
- King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
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Ordóñez-Sanz C, Cowen M, Shiravand N, MacDougall ND. CBCT imaging: a simple approach for optimising and evaluating concomitant imaging doses, based on patient-specific attenuation, during radiotherapy pelvis treatment. Br J Radiol 2021; 94:20210068. [PMID: 34282947 PMCID: PMC8523193 DOI: 10.1259/bjr.20210068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objectives: A simple, robust method, for optimising cone-beam CT (CBCT) dose and image quality for pelvis treatment, based on patient-specific attenuation. Methods: Methods were investigated for grouping patients into four imaging categories (small [S], medium [M], large [L], extra large [XL]), based on planning-CT CTDIvol, and phantoms constructed to represent each group. CBCTs with varying kV, mA and ms honed in on the best settings, with a bladder noise of 25 HU. A patient pilot study clinically verified the new imaging settings. Results: The planning CTDIvol is a reliable method for grouping patients. Phantom measurements from the S, M and L groups show doses significantly reduced (19–83% reduction), whilst the XL group required an increase of 39%. Phantom TLD measurements showed the number of scans needed to increase rectal organ at risk (OAR) dose by 1 Gy was 143 (S group) and 50 (M group). Images were qualitatively assessed as sufficient by clinicians. Conclusion: Patient-specific CBCT modes are in use clinically with dose reductions across all modes except Pelvis XL, keeping doses ALARP and images optimal. Consideration of OAR doses controls the number of CBCTs allowed to ensure adherence to OAR tolerance. Reporting CBCT doses in “scans per Gray” allows clinicians to make informed decisions regarding the imaging schedule and concomitant doses. Advances in knowledge: Patient grouping at planning CT, using CTDIvol, allows for CBCT imaging protocols to be selected based on patient specific attenuation. Reporting OAR doses in terms of “scans per Gray” allows translation of imaging dose risk to the Oncologist.
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Affiliation(s)
| | - Mark Cowen
- North West Anglia NHS Foundation Trust, England, UK
| | - Neda Shiravand
- Radiotherapy Physics, St Bartholomew's Hospital, London, UK
| | - Niall D MacDougall
- Radiotherapy Physics, St Bartholomew's Hospital, London, UK.,Barts Cancer Institute, Queen Mary University of London, London, UK
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García-Hernández T, Romero-Expósito M, Sánchez-Nieto B. Low dose radiation therapy for COVID-19: Effective dose and estimation of cancer risk. Radiother Oncol 2020; 153:289-295. [PMID: 33065184 PMCID: PMC7553901 DOI: 10.1016/j.radonc.2020.09.051] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/16/2020] [Accepted: 09/27/2020] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND PURPOSE The objective of this work is to evaluate the risk of carcinogenesis of low dose ionizing radiation therapy (LDRT), for treatment of immune-related pneumonia following COVID-19 infection, through the estimation of effective dose and the lifetime attributable risk of cancer (LAR). MATERIAL AND METHODS LDRT treatment was planned in male and female computational phantoms. Equivalent doses in organs were estimated using both treatment planning system calculations and a peripheral dose model (based on ionization chamber measurements). Skin dose was estimated using radiochromic films. Later, effective dose and LAR were calculated following radiation protection procedures. RESULTS Equivalent doses to organs per unit of prescription dose range from 10 mSv/cGy to 0.0051 mSv/cGy. Effective doses range from 204 mSv to 426 mSv, for prescription doses ranging from 50 cGy to 100 cGy. Total LAR for a prescription dose of 50 cGy ranges from 1.7 to 0.29% for male and from 4.9 to 0.54% for female, for ages ranging from 20 to 80 years old. CONCLUSIONS The organs that mainly contribute to risk are lung and breast. Risk for out-of-field organs is low, less than 0.06 cases per 10000. Female LAR is on average 2.2 times that of a male of the same age. Effective doses are of the same order of magnitude as the higher-dose interventional radiology techniques. For a 60 year-old male, LAR is 8 times that from a cardiac CT, when prescription dose is 50 cGy.
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Affiliation(s)
| | - Maite Romero-Expósito
- Área de Ciencias Básicas y Ambientales, Instituto Tecnológico de Santo Domingo (INTEC), P.O. Box 342-9/249-2, Santo Domingo, Dominican Republic
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Piliero MA, Casiraghi M, Bosetti DG, Cima S, Deantonio L, Leva S, Martucci F, Tettamanti M, Pupillo F, Bellesi L, Richetti A, Presilla S. Patient-based low dose cone beam CT acquisition settings for prostate image-guided radiotherapy treatments on a Varian TrueBeam linear accelerator. Br J Radiol 2020; 93:20200412. [PMID: 32822249 PMCID: PMC8519649 DOI: 10.1259/bjr.20200412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVE To evaluate the performance of low dose cone beam CT (CBCT) acquisition protocols for image-guided radiotherapy of prostate cancer. METHODS CBCT images of patients undergoing prostate cancer radiotherapy were acquired with the settings currently used in our department and two low dose settings at 50% and 63% lower exposure. Four experienced radiation oncologists and two radiation therapy technologists graded the images on five image quality characteristics. The scores were analysed through Visual Grading Regression, using the acquisition settings and the patient size as covariates. RESULTS The low dose acquisition settings have no impact on the image quality for patients with body profile length at hip level below 100 cm. CONCLUSIONS A reduction of about 60% of the dose is feasible for patients with size below 100 cm. The visibility of low contrast features can be compromised if using the low dose acquisition settings for patients with hip size above 100 cm. ADVANCES IN KNOWLEDGE Low dose CBCT acquisition protocols for the pelvis, based on subjective evaluation of patient images.
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Affiliation(s)
- Maria Antonietta Piliero
- Medical Physics Division, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, 6500 Bellinzona, Switzerland
| | - Margherita Casiraghi
- Medical Physics Division, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, 6500 Bellinzona, Switzerland
| | - Davide Giovanni Bosetti
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Simona Cima
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Letizia Deantonio
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Stefano Leva
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Francesco Martucci
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Marino Tettamanti
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Francesco Pupillo
- Medical Physics Division, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, 6500 Bellinzona, Switzerland
| | - Luca Bellesi
- Medical Physics Division, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, 6500 Bellinzona, Switzerland
| | - Antonella Richetti
- Radiation Oncology Clinic, Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland
| | - Stefano Presilla
- Medical Physics Division, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, 6500 Bellinzona, Switzerland
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Kairn T, Livingstone AG, Crowe SB. Monte Carlo calculations of radiotherapy dose in "homogeneous" anatomy. Phys Med 2020; 78:156-165. [PMID: 33035927 DOI: 10.1016/j.ejmp.2020.09.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/05/2020] [Accepted: 09/21/2020] [Indexed: 01/27/2023] Open
Abstract
Given the substantial literature on the use of Monte Carlo (MC) simulations to verify treatment planning system (TPS) calculations of radiotherapy dose in heterogeneous regions, such as head and neck and lung, this study investigated the potential value of running MC simulations of radiotherapy treatments of nominally homogeneous pelvic anatomy. A pre-existing in-house MC job submission and analysis system, built around BEAMnrc and DOSXYZnrc, was used to evaluate the dosimetric accuracy of a sample of 12 pelvic volumetric arc therapy (VMAT) treatments, planned using the Varian Eclipse TPS, where dose was calculated with both the Analytical Anisotropic Algorithm (AAA) and the Acuros (AXB) algorithm. In-house TADA (Treatment And Dose Assessor) software was used to evaluate treatment plan complexity, in terms of the small aperture score (SAS), modulation index (MI) and a novel exposed leaf score (ELS/ELA). Results showed that the TPS generally achieved closer agreement with the MC dose distribution when treatments were planned for smaller (single-organ) targets rather than larger targets that included nodes or metastases. Analysis of these MC results with reference to the complexity metrics indicated that while AXB was useful for reducing dosimetric uncertainties associated with density heterogeneity, the residual TPS dose calculation uncertainties resulted from treatment plan complexity and TPS model simplicity. The results of this study demonstrate the value of using MC methods to recalculate and check the dose calculations provided by commercial radiotherapy TPSs, even when the treated anatomy is assumed to be comparatively homogeneous, such as in the pelvic region.
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Affiliation(s)
- Tanya Kairn
- Royal Brisbane and Women's Hospital, Butterfield Street, Herston, QLD 4029, Australia; Queensland University of Technology, 2 George Street, Brisbane, QLD 4000, Australia.
| | | | - Scott B Crowe
- Royal Brisbane and Women's Hospital, Butterfield Street, Herston, QLD 4029, Australia; Queensland University of Technology, 2 George Street, Brisbane, QLD 4000, Australia
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Abuhaimed A, Martin CJ. A Monte Carlo investigation of dose length product of cone beam computed tomography scans. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:393-409. [PMID: 31986511 DOI: 10.1088/1361-6498/ab703c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The dose length product (DLP) provides a measurement related to energy imparted from a computed tomography (CT) scan. The DLP is based on the volume-averaged CT dose index (CTDI vol), which is designed for fan beams. The aims of this study were to investigate the use of DLP for scans with wide beams used in cone beam CT (DLP CBCT) in radiotherapy that would be analogous to the DLP of fan beam scans (DLP CT), and to compare the efficiencies of DLP CT and DLP CBCT in reporting the total energy imparted in patients. A validated Monte Carlo model of a kV imaging system integrated into a Varian TrueBeam linac was employed. The DLP CT was assessed by multiplying the CTDI vol for a 20 mm fan beam by scan length, and the DLP CBCT determined through multiplying the CTDI vol, estimated for wide beams using a correction factor based on free-in-air measurements, by the beam width. Two scan protocols for head and body were investigated for tube potentials between 80 and 140 kV and a range of scan lengths/widths. Efficiency values were estimated by normalising the DLP CT and DLP CBCT with respect to the corresponding dose profile integrals (DPIs), which were evaluated within 900 mm long phantoms. The results show that the DLP CBCT values were within 1% of those for DLP CT of similar length performed on the same system, and the efficiencies decrease with tube potential. However, whereas DLP values for fan beams are approximately proportional to scan length, those for wide beams decrease by ∼2% between beam widths of 20 and 320 mm. As a result, while the DLP CT efficiency is similar over all scan lengths, that for DLP CBCT increases slightly with beam width. The DLP CT and DLP CBCT underestimated the total energy imparted by comparable amounts with efficiencies within the range of 80-81% and 80-83% for the head scans, and 71-76% and 70-77% for the body scans, respectively. The results indicate that the DLP CBCT can be considered as an analogous dose index to the DLP CT. It could, therefore, be used for quantification of doses from imaging in radiotherapy and provide a valuable tool to aid optimisation.
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Affiliation(s)
- Abdullah Abuhaimed
- King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
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Tomita T, Isobe T, Furuyama Y, Takei H, Kobayashi D, Mori Y, Terunuma T, Sato E, Yokota H, Sakae T. Evaluation of Dose Distribution and Normal Tissue Complication Probability of a Combined Dose of Cone-Beam Computed Tomography Imaging with Treatment in Prostate Intensity-Modulated Radiation Therapy. J Med Phys 2020; 45:78-87. [PMID: 32831490 PMCID: PMC7416863 DOI: 10.4103/jmp.jmp_4_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/02/2020] [Accepted: 03/31/2020] [Indexed: 12/03/2022] Open
Abstract
Purpose: The purpose of this study is to evaluate the effects of cone-beam computed tomography (CBCT) on dose distribution and normal tissue complication probability (NTCP) by constructing a comprehensive dose evaluation system for prostate intensity-modulated radiation therapy (IMRT). Methods: A system that could combine CBCT and treatment doses with MATLAB was constructed. Twenty patients treated with prostate IMRT were studied. A mean dose of 78 Gy was prescribed to the prostate region, excluding the rectal volume from the target volume, with margins of 4 mm to the dorsal side of the prostate and 7 mm to the entire circumference. CBCT and treatment doses were combined, and the dose distribution and the NTCP of the rectum and bladder were evaluated. Results: The radiation dose delivered to 2% and 98% of the target volume increased by 0.90 and 0.74 Gy on average, respectively, in the half-fan mode and on average 0.76 and 0.72 Gy, respectively, in the full-fan mode. The homogeneity index remained constant. The percent volume of the rectum and bladder irradiated at each dose increased slightly, with a maximum increase of <1%. The rectal NTCP increased by approximately 0.07% from 0.46% to 0.53% with the addition of a CBCT dose, while the maximum NTCP in the bladder was approximately 0.02%. Conclusions: This study demonstrated a method to evaluate a combined dose of CBCT and a treatment dose using the constructed system. The combined dose distribution revealed increases of <1% volume in the rectal and bladder doses and approximately 0.07% in the rectal NTCP.
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Affiliation(s)
- Tetsuya Tomita
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.,Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan
| | - Tomonori Isobe
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | | | - Hideyuki Takei
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Daisuke Kobayashi
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.,Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan
| | - Yutaro Mori
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | | | - Eisuke Sato
- Faculty of Health Sciences, Juntendo University, Tokyo, Japan
| | - Hiroshi Yokota
- Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan
| | - Takeji Sakae
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
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Liang AK, El-Mohri Y, Zhao Q, Koniczek M, Antonuk LE. Count rate capabilities of polycrystalline silicon photon counting detectors for CBCT applications-a theoretical study. Phys Med Biol 2020; 65:035009. [PMID: 31874461 DOI: 10.1088/1361-6560/ab6577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The signal-to-noise properties of active matrix, flat-panel imagers (AMFPIs) limit the imaging performance of this x-ray imaging technology under conditions of low dose per image frame. This limitation can affect cone-beam computed tomography (CBCT) procedures where an AMFPI is used to acquire hundreds of image frames to form a single volumetric data set. An approach for overcoming this limitation is to replace the energy-integrating pixel circuits of AMFPI arrays with photon counting pixel circuits which examine the energy of each x-ray interaction and count those events whose signals exceed user-defined energy thresholds. A promising material for fabricating the circuits of such photon-counting detectors (PCDs) is polycrystalline silicon (poly-Si)-a semiconductor that facilitates economic manufacture of large area, monolithic arrays of the size presently provided by AMFPIs as well as provides good radiation damage resistance. In this paper, results are reported from a theoretical investigation of the potential for poly-Si PCDs to satisfy the count rate needs, while maintaining good energy resolution, of two CBCT applications-CBCT used for breast imaging and kilo-voltage CBCT used for providing localization information in image guided radiotherapy (referred to as BCT and kV-CBCT, respectively). The study focused on the performance of the critical first component of a PCD pixel circuit, the amplifier, under conditions relevant to the two applications. The study determined that, compared to the average input fluxes associated with BCT and kV-CBCT, a promising amplifier design employing poly-Si thin-film transistors can provide count rates two and four times in excess of those levels, respectively, assuming a dead time loss of 10%. In addition, calculational estimates based on foreseeable poly-Si circuit densities suggest that it should be possible to include sufficient circuitry to support 2 and 3 energy thresholds per pixel, respectively. Finally, prospects for further improvements are discussed.
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Affiliation(s)
- Albert K Liang
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, United States of America
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Yuasa Y, Shiinoki T, Onizuka R, Fujimoto K. Estimation of effective imaging dose and excess absolute risk of secondary cancer incidence for four-dimensional cone-beam computed tomography acquisition. J Appl Clin Med Phys 2019; 20:57-68. [PMID: 31593377 PMCID: PMC6839364 DOI: 10.1002/acm2.12741] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 09/02/2019] [Accepted: 09/15/2019] [Indexed: 12/25/2022] Open
Abstract
This study was conducted to estimate the organ equivalent dose and effective imaging dose for four-dimensional cone-beam computed tomography (4D-CBCT) using a Monte Carlo simulation, and to evaluate the excess absolute risk (EAR) of secondary cancer incidence. The EGSnrc/BEAMnrc were used to simulate the on-board imager (OBI) from the TrueBeam linear accelerator. Specifically, the OBI was modeled based on the percent depth dose and the off-center ratio was measured using a three-dimensional (3D) water phantom. For clinical cases, 15 lung and liver cancer patients were simulated using the EGSnrc/DOSXYZnrc. The mean absorbed doses to the lung, stomach, bone marrow, esophagus, liver, thyroid, bone surface, skin, adrenal glands, gallbladder, heart, intestine, kidney, pancreas and spleen, were quantified using a treatment planning system, and the equivalent doses to each organ were calculated. Subsequently, the effective dose was calculated as the weighted sum of the equivalent dose, and the EAR of the secondary cancer incidence was determined for each organ with the use of the biologic effects of ionizing radiation (BEIR) VII model. The effective doses were 3.9 ± 0.5, 15.7 ± 2.0, and 7.3 ± 0.9 mSv, for the lung, and 4.2 ± 0.6, 16.7 ± 2.4, and 7.8 ± 1.1 mSv, for the liver in the respective cases of the 3D-CBCT (thorax, pelvis) and 4D-CBCT modes. The lung EARs for males and females were 7.3 and 10.7 cases per million person-years, whereas the liver EARs were 9.9 and 4.5 cases per million person-years. The EAR increased with increasing time since radiation exposure. In clinical studies, we should use 4D-CBCT based on consideration of the effective dose and EAR of secondary cancer incidence.
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Affiliation(s)
- Yuki Yuasa
- Department of Radiation OncologyGraduate School of MedicineYamaguchi UniversityUbeYamaguchiJapan
| | - Takehiro Shiinoki
- Department of Radiation OncologyGraduate School of MedicineYamaguchi UniversityUbeYamaguchiJapan
| | - Ryota Onizuka
- Department of Radiological TechnologyYamaguchi University HospitalUbeYamaguchiJapan
| | - Koya Fujimoto
- Department of Radiation OncologyGraduate School of MedicineYamaguchi UniversityUbeYamaguchiJapan
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Abuhaimed A, Martin CJ, Demirkaya O. Influence of cone beam CT (CBCT) scan parameters on size specific dose estimate (SSDE): a Monte Carlo study. ACTA ACUST UNITED AC 2019; 64:115002. [DOI: 10.1088/1361-6560/ab0bc8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Kralik I, Faj D, Lauc T, Škarica M, Popić J, Brkic H. Dose area product in estimation of effective dose of the patients undergoing dental cone beam computed tomography examinations. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2018; 38:1412-1427. [PMID: 30264736 DOI: 10.1088/1361-6498/aae4e8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
OBJECTIVE To investigate the relationship of the effective dose and dose area product (DAP) in dental cone beam computed tomography (CBCT) examinations and to propose conversion factors for estimation of effective doses of the patients using DAP. Dependence of organ doses on DAP was also investigated. MATERIALS AND METHODS Different exposure geometries in Cranex3Dx CBCT device were simulated using Monte Carlo simulation and computational anthropomorphic phantom. Then organ doses and effective dose for every exposure geometry was compared to DAP and analysed. RESULTS The effective dose in all simulated CBCT protocols and positions with 180° tube rotation ranged from 5 μSv for 50 × 50 mm2 field of view (FOV) localised on one tooth using lowest resolution to 265 μSv for the largest FOV and highest resolution. In case of 360° tube rotation the effective dose ranges from 6 to 332 μSv for the same FOV sizes and positions as well as resolutions as in 180° tube rotation. CONCLUSIONS Though the DAP introduces a large uncertainty in the risk measure in dental CBCT, it represents the dose and FOV size which are the most important scanning parameters affecting the dose. To decrease uncertainty in the risk measure, the effective dose has to be estimated for usual clinical positions of the FOV.
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Abuhaimed A, Martin CJ. A Monte Carlo study of impact of scan position for cone beam CT on doses to organs and effective dose. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abuhaimed A, Martin CJ. Evaluation of coefficients to derive organ and effective doses from cone-beam CT (CBCT) scans: a Monte Carlo study. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2018; 38:189-206. [PMID: 29154259 DOI: 10.1088/1361-6498/aa9b9f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Regular imaging is used throughout image guided radiation therapy to improve treatment delivery. In order for treatment procedures to be optimized, the doses delivered by imaging exposures should be taken into account. CT dosimetry methods based on the CT dose index (CTDI), measured with a 100 mm long pencil ionization chamber (CTDI100) in standard phantoms, are not designed for cone-beam CT (CBCT) imaging systems used in radiotherapy, therefore a modified version has been proposed for CBCT by the International Electrotechnical Commission (CTDIIEC). Monte Carlo simulations based on a Varian On-Board Imaging system were used to derive conversion coefficients that enable organ doses for ICRP reference phantoms to be determined from the CTDIIEC for different scan protocols and different beam widths (80-320) mm. A dose-width product calculated by multiplying the CTDIIEC by the width of the CBCT beam is proposed as a quantity that can be used for estimating effective dose. The variation in coefficients with CBCT beam width was studied. Coefficients to allow estimation of effective doses were derived, namely 0.0034 mSv (mGy cm)-1 for the head, 0.0252 mSv (mGy cm)-1 for the thorax, 0.0216 mSv (mGy cm)-1 for the abdomen and 0.0150 mSv (mGy cm)-1 for the pelvis, and these may be applicable more generally to other CBCT systems in radiotherapy. If data on effective doses are available, these can be used in making judgements on the contributions to patient dose from imaging, and thereby assist in optimization of the treatment regimes. The coefficients can also be employed in converting dosimetry data recorded in patient records into quantities relating directly to patient doses.
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Affiliation(s)
- Abdullah Abuhaimed
- The National Centre for Applied Physics, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
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