scholarly journals The Effects Of High Dose and Low Dose Protocols In Thorax’s CT Scan Image Quality

2021 ◽  
Vol 11 (2) ◽  
pp. 189
Author(s):  
Ni Larasati Kartika Sari ◽  
Deni Tiko Bahagia ◽  
Puji Hartoyo ◽  
Dewi Muliyati
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Ct Scan ◽  
Spatial Resolution ◽  
Low Dose ◽  
High Dose ◽  
Ct Number ◽  
Noise Ratio ◽  
Computed Tomography Dose Index ◽  
Dose Index

<p class="AbstractHeading">ABSTRACT</p><p class="AbstractText">The aim of this research was to evaluate the effects of two different dose protocols’ usage on image quality. This research was performed on three different CT Scanners using high dose and low dose protocols of thorax scan. Different exposure parameters were used, depending on each scanner’s setting. GE QA CT Scan phantom was used for image quality assessment.  Image quality measured were CT number accuracy, uniformity and linearity, noise uniformity, spatial resolution and Contrast To Noise Ratio (CNR). CT Scan’s dose index, CTDIvol (Volumetric Computed Tomography Dose Index), was also measured to evaluate how these two protocols work in reducing radiation dose. The result showed that the usage of low dose protocols reduce the CTDIvol value at 85-91% compared to the high dose protocols, meanwhile most of the image quality parameters obtained from both protocols were still considered good. The CT number accuracy, uniformity, linearity and noise uniformity for all CT Scans were all still inside BAPETEN’s (Indonesia National Regulator Agency) threshold. There were 20-23% difference on the spatial resolution value measured from both protocols. The most significant difference came from CNR. The CNR obtained from high dose protocols were 65-93% higher than the one from low dose protocols.   </p><p class="AbstractText">Keywords: contrast to noise ratio, CTDIvol, CT number, spatial resolution</p><p class="AbstractHeading">ABSTRAK</p><p>Penelitian ini mengevaluasi pengaruh penggunanaan protokol dosis tinggi dan protokol dosis rendah terhadap kualitias citra dan dosis khususnya pada pemeriksaan CT Scan thorax. Penelitian ini dilakukan pada 3 sampel CT Scan yang berbeda. Faktor eksposi yang digunakan berbeda untuk tiap scanner, bergantung pada setting yang terdapat pada scanner. Fantom yagdigunakan untuk menilai kualitas citra adalah fantom GE QA CT Scan. Adapun kualitas citra yang diukur adalah keseragaman, akurasi, dan linearitas CT number, keseragaman noise, resolusi spasial, serta <em>Contrast to Noise Ratio</em> (CNR). Sementara dosis radiasi yang diamati adalah CTDIvol (Volumetrik <em>Computed Tomography Dose Index</em>) yang tampil pada konsol. Hasil penelitian ini menunjukkan bahwa penggunaan protokol dosis rendah mampu mengurangi nilai CTDIvol sebesar 85-91% dibanding dengan protokol dosis tinggi, sementara sebagian besar parameter kualitas citra yang diukur masih dinilai baik. Nilai akurasi, keseragaman, dan linearitas CT number  serta keseragaman noise pada protokol dosis tinggi dan dosis rendah, keseluruhannya masih dalam batas ambang BAPETEN. Terdapat perbedaan sebesar 20-23% pada nilai resolusi spasial yang terukur dari  kedua protokol. Nilai CNR pada protokol dosis tinggi lebih baik dari pada protokol dosis rendah, dengan perbedaan yang cukup signifikan, yaitu 65-93%.</p><p class="AbstractText">Kata kunci: <em>contrast to noise ratio</em>, CTDIvol, <em>CT number</em>, resolusi spasial</p>

Flat Panel Cone Beam Computed Tomography of the Sinuses

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P77-P78
Author(s):  
Richard A Zoumalan ◽  
Kathryn Shouyee Yung ◽  
Edwin Wang ◽  
Richard A Lebowitz ◽  
Joseph B Jacobs
Keyword(s):  
Image Quality ◽  
Ct Scan ◽  
Low Dose ◽  
Multidetector Ct ◽  
Imaging Modality ◽  
Cone Beam Ct ◽  
Image Noise ◽  
Cone Beam ◽  
High Dose ◽  
Flat Panel

Objective Flat panel cone beam CT is a relatively new technology that improves upon traditional multidetector CT scanners by generating images with greater spatial resolution at lower radiation doses. 1) Learn whether flat panel cone beam CT evaluation is an effective imaging modality for the sinuses. 2) Learn which doses of radiation provide quality evaluation of the sinuses while exposing the patient to the least amount of radiation. Methods In 2007, a panel consisting of neuroradiologists and otolaryngologists blindly reviewed images from flat panel sinus CTs (Xoran MiniCAT) of 11 live human subjects, each irradiated at all 3 different techniques (denoted as: low dose mAs=9.27, medium dose mAs = 18.41, high dose mAs=36.7) and rated the image quality of a pre-designated list of sinus anatomic structures. Techniques were compared in a pairwise manner using a Wilcoxon matched-pairs signed ranks test. Results Compared to the low dose technique CT scan, the high dose CT scan technique had significantly better image quality (P=.0029) and image noise (P=.0049). Similarly, the medium dose CT scan technique had significantly better image quality (P=.0020) and image noise (P = .0010) compared to the low dose technique. No difference in image quality and image noise existed between the medium and high dose techniques. No difference in visualization of 13 specific anatomic structures existed between any of the dose techniques. Conclusions Lower dose CT techniques achieved by flat panel cone beam CT may be an effective and safe alternative to traditional multidetector CT scanners. This imaging modality may help patients avoid unnecessary radiation to sensitive organs.

scholarly journals Iterative reconstruction improves image quality and reduces radiation dose in trauma protocols; A human cadaver study

2021 ◽  
Vol 10 (10) ◽  
pp. 205846012110553
Author(s):  
Johannes Clemens Godt ◽  
Cathrine K Johansen ◽  
Anne Catrine T Martinsen ◽  
Anselm Schulz ◽  
Helga M Brøgger ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Dose Reduction ◽  
Iterative Reconstruction ◽  
Low Dose ◽  
Human Cadaver ◽  
Full Dose ◽  
Significant Difference ◽  
Noise Ratio ◽  
Dose Levels

Background Radiation-related cancer risk is an object of concern in CT of trauma patients, as these represent a young population. Different radiation reducing methods, including iterative reconstruction (IR), and spilt bolus techniques have been introduced in the recent years in different large scale trauma centers. Purpose To compare image quality in human cadaver exposed to thoracoabdominal computed tomography using IR and standard filtered back-projection (FBP) at different dose levels. Material and methods Ten cadavers were scanned at full dose and a dose reduction in CTDIvol of 5 mGy (low dose 1) and 7.5 mGy (low dose 2) on a Siemens Definition Flash 128-slice computed tomography scanner. Low dose images were reconstructed with FBP and Sinogram affirmed iterative reconstruction (SAFIRE) level 2 and 4. Quantitative image quality was analyzed by comparison of contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). Qualitative image quality was evaluated by use of visual grading regression (VGR) by four radiologists. Results Readers preferred SAFIRE reconstructed images over FBP at a dose reduction of 40% (low dose 1) and 56% (low dose 2), with significant difference in overall impression of image quality. CNR and SNR showed significant improvement for images reconstructed with SAFIRE 2 and 4 compared to FBP at both low dose levels. Conclusions Iterative image reconstruction, SAFIRE 2 and 4, resulted in equal or improved image quality at a dose reduction of up to 56% compared to full dose FBP and may be used a strong radiation reduction tool in the young trauma population.

Analisis Dosis Serap CT Scan Thorax Dengan Computed Tomography Dose Index Dan Thermoluminescence Dosimeter

2019 ◽  
Vol 20 (1) ◽  
pp. 10
Author(s):  
Lutfiana Desy Saputri ◽  
Budi Santoso ◽  
Agung Nugroho Oktavianto ◽  
Febria Anita
Keyword(s):  
Computed Tomography ◽  
Ct Scan ◽  
European Commission ◽  
Dose Length Product ◽  
Thermoluminescence Dosimeter ◽  
Computed Tomography Dose Index ◽  
Dose Index

Pemeriksaan CT scan thorax banyak digunakan dirumah sakit untuk mengetahui penyakit atau kelainan yang terdapat pada mediastinum atau paru-paru. Selama scanning, pasien mendapatkan radiasi pada pesawat CT scan. Perkiraan dosis yang diterima pasien sudah ada pada layar monitor yaitu nilai CTDI, namun untuk mengetahui dosis sebenarnya yang diterima pasien maka perlu pengukuran langsung menggunakan TLD yang ditempelkan pada tubuh pasien selama proses scanning. Tujuan penelitian ini adalah untuk mengetahui besarnya dosis yang diterima pasien selama CT scan thorax, membandingkan besar dosis yang diterima pasien dengan menggunakan TLD dan nilai CTDI yang tertera pada layar monitor selama CT scan thorax, mengetahui hasil ukur dosis masih dalam batas panduan monitor selama CT scan yang ditetapkan atau tidak, mengetahui hubungan antara hasil ukur dosis dengan DLP pada pasien selama CT Scan thorax. Penelitian diawali dengan pengukuran konsistensi keluaran tegangan tabung sinar-X (kVp Output). Lalu dilakukan pengukuran dosis radiasi pada area thorax dengan menggunakan chips TLD-100 yang ditempelkan pada permukaan area thorax terhadap 9 pasien yang berbeda-beda. Chips TLD-100 ditempelkan pada 3 titik yaitu caput humerus kanan, caput humerus kiri, dan sternum. Hasil penelitian menunjukkan bahwa (1) besarnya dosis radiasi yang diterima pasien selama CT scan thorax sebesar 16,19 mGy sampai dengan 27,66 mGy. (2) prosentasi perbedaan hasil ukur terhadap CTDI vol sebesar 0,06%-70,74%, adanya perbedaan rerata dosis pada tiga titik pengukuran yaitu caput humerus kanan sebesar 17,6 mGy, caput humerus kiri sebesar 16,52 mGy, dan sternum sebesar 25,4 mGy. (3) penerimaan dosis rata-rata pasien pada CT Scan thorax masih dalam batas panduan dosis CT scan yang ditetapkan oleh European Commission, yaitu sebesar 30 mGyuntuk CT thorax rutin, namun nilai DLP yang didapatkan berada diatas panduan dosis yang ditetapkan. (4) hasil ukur dosis berbanding lurus dengan DLP ( dose length ProduCT) yang diterima pasien.

scholarly journals Analisis Variasi Faktor Eksposi dan Ketebalan Irisan Terhadap CTDI dan Kualitas Citra Pada Computed Tomography Scan

2019 ◽  
Vol 7 (1) ◽  
pp. 7
Author(s):  
Arry Y. Nurhayati ◽  
Nia N. Nariswari ◽  
B. Rahayuningsih ◽  
Yuda C. Hariadi
Keyword(s):  
Computed Tomography ◽  
Ct Scan ◽  
Computed Tomography Scan ◽  
Computed Tomography Dose Index ◽  
Tomography Scan ◽  
Dose Index

CT Scan merupakan alat pencitraan sinar-X yang dipadukan dengan komputer pengolah data sehingga mampu menghasilkan gambar potongan melintang tubuh dan memiliki dosis relatif lebih tinggi, karena berasal dari radiasi primer dan radiasi hambur dari setiap slice. Dosis yang dihasilkan dipengaruhi oleh parameter scan yaitu faktor eksposi (tegangan tabung, arus- waktu rotasi) dan ketebalan irisan. Kuantitas dosis pada pemeriksaan CT Scan digunakan metode Computed Tomography Dose Index (CTDI). Penelitian ini dilakukan untuk mengatahui efek variasi parameter scan terhadap CTDI dan kualitas citra dengan menggunakan phantom. Hasil data yang diperoleh menunjukkan bahwa pada variasi 200 mAs, 120 kV dan 5 mm menghasilkan CTDIvol dan CNR optimum dengan nilai masing-masing 25.8 mGy dan 3.51. Hal ini disebabkan adanya keseimbangan nilai antara faktor eksposi yang tidak memiliki rentang yang terlalu jauh sehingga menghasilkan energi dan kuantitas sinar X yang seimbang dan ketebalan irisan tidak menghasilkan noise tinggi sehingga objek dalam phantom tetap dapat terlihat lebih baik. Kata Kunci: CT Scan, CTDI, CTDIvol, LCR, CNR.

High-quality low-dose cardiovascular computed tomography (CCT) in pediatric patients using a 64-slice scanner

2018 ◽  
Vol 59 (10) ◽  
pp. 1247-1253 ◽  
Author(s):  
Paola Maria Cannaò ◽  
Francesco Secchi ◽  
Marco Alì ◽  
Ida Daniela D'Angelo ◽  
Marco Scarabello ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Radiation Dose ◽  
Effective Dose ◽  
Low Dose ◽  
Signal To Noise Ratio ◽  
High Quality ◽  
Dose Length Product ◽  
Noise Ratio ◽  
Estimate Radiation Dose

Background Cardiovascular computed tomography (CCT) technology is rapidly advancing allowing to perform good quality examinations with a radiation dose as low as 1.2 mSv. However, latest generation scanners are not available in all centers. Purpose To estimate radiation dose and image quality in pediatric CCT using a standard 64-slice scanner. Material and Methods A total of 100 patients aged 6.9 ± 5.4 years (mean ± standard deviation) who underwent a 64-slice CCT scan using 80, 100, or 120 kVp, were retrospectively evaluated. Radiation effective dose was calculated on the basis of the dose length product. Two independent readers assessed the image quality through signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and a qualitative score (3 = very good, 2 = good, 1 = poor). Non-parametric tests were used. Results Fifty-five exams were not electrocardiographically (ECG) triggered, 20 had a prospective ECG triggering, and 25 had retrospective ECG triggering. The median effective dose was 1.3 mSv (interquartile range [IQR] = 0.8–2.7 mSv). Median SNR was 30.6 (IQR = 23.4–33.6) at 120 kVp, 29.4 (IQR = 23.7–34.8) at 100 kVp, and 24.7 (IQR = 19.4–34.3) at 80 kVp. Median CNR was 21.0 (IQR = 14.8–24.4), 19.1 (IQR = 15.6–23.9), and 25.3 (IQR = 19.4–33.4), respectively. Image quality was very good, good, and poor in 56, 39, and 5 patients, respectively. No significant differences were found among voltage groups for SNR ( P = 0.486), CNR ( P = 0.336), and subjective image quality ( P = 0.296). The inter-observer reproducibility was almost perfect (κ = 0.880). Conclusion High-quality pediatric CCT can be performed using a 64-slice scanner, with a radiation effective dose close to 2 mSv in about 50% of the cases.

scholarly journals Assessment of computed tomography dose index (CTDI) using the platform GEANT4/GATE

2019 ◽  
Vol 12 ◽  
pp. 100405
Author(s):  
M. Mkimel ◽  
M.R. Mesradi ◽  
R. El Baydaoui ◽  
Y. Toufique ◽  
Z. Aitelcadi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Computed Tomography Dose Index ◽  
Dose Index

Using 100- instead of 120-kVp computed tomography to diagnose pulmonary embolism almost halves the radiation dose with preserved diagnostic quality

2010 ◽  
Vol 51 (3) ◽  
pp. 260-270 ◽  
Author(s):  
Peter Björkdahl ◽  
Ulf Nyman
Keyword(s):  
Computed Tomography ◽  
Pulmonary Embolism ◽  
Image Quality ◽  
Radiation Dose ◽  
Effective Dose ◽  
Ct Number ◽  
Subjective Image Quality ◽  
Diagnostic Quality ◽  
X Ray ◽  
Tube Potential

Background: Concern has been raised regarding the mounting collective radiation doses from computed tomography (CT), increasing the risk of radiation-induced cancers in exposed populations. Purpose: To compare radiation dose and image quality in a chest phantom and in patients for the diagnosis of pulmonary embolism (PE) at 100 and 120 peak kilovoltage (kVp) using 16-multichannel detector computed tomography (MDCT). Material and Methods: A 20-ml syringe containing 12 mg I/ml was scanned in a chest phantom at 100/120 kVp and 25 milliampere seconds (mAs). Consecutive patients underwent 100 kVp ( n = 50) and 120 kVp ( n = 50) 16-MDCT using a “quality reference” effective mAs of 100, 300 mg I/kg, and a 12-s injection duration. Attenuation (CT number), image noise (1 standard deviation), and contrast-to-noise ratio (CNR; fresh clot = 70 HU) of the contrast medium syringe and pulmonary arteries were evaluated on 3-mm-thick slices. Subjective image quality was assessed. Computed tomography dose index (CTDIvol) and dose–length product (DLP) were presented by the CT software, and effective dose was estimated. Results: Mean values in the chest phantom and patients changed as follows when X-ray tube potential decreased from 120 to 100 kVp: attenuation +23% and +40%, noise +38% and +48%, CNR −6% and 0%, and CTDIvol −38% and −40%, respectively. Mean DLP and effective dose in the patients decreased by 42% and 45%, respectively. Subjective image quality was excellent or adequate in 49/48 patients at 100/120 kVp. No patient with a negative CT had any thromboembolism diagnosed during 3-month follow-up. Conclusion: By reducing X-ray tube potential from 120 to 100 kVp, while keeping all other scanning parameters unchanged, the radiation dose to the patient may be almost halved without deterioration of diagnostic quality, which may be of particular benefit in young individuals.

An evaluation of computed tomography dose index measurements using a pencil ionisation chamber and small detectors

2019 ◽  
Vol 39 (1) ◽  
pp. 112-124 ◽  
Author(s):  
Choirul Anam ◽  
Toshioh Fujibuchi ◽  
Freddy Haryanto ◽  
Rena Widita ◽  
Idam Arif ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Ionisation Chamber ◽  
Computed Tomography Dose Index ◽  
Dose Index

scholarly journals Low-Dose Computed Tomography for the Optimization of Radiation Dose Exposure in Patients with Crohn’s Disease

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Richard G. Kavanagh ◽  
John O’Grady ◽  
Brian W. Carey ◽  
Patrick D. McLaughlin ◽  
Siobhan B. O’Neill ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Crohn’S Disease ◽  
Image Quality ◽  
Crohn's Disease ◽  
Radiation Dose ◽  
Ionizing Radiation ◽  
Low Dose ◽  
Radiation Doses ◽  
Radiation Dose Exposure ◽  
Ct Technology

Magnetic resonance imaging (MRI) is the mainstay method for the radiological imaging of the small bowel in patients with inflammatory bowel disease without the use of ionizing radiation. There are circumstances where imaging using ionizing radiation is required, particularly in the acute setting. This usually takes the form of computed tomography (CT). There has been a significant increase in the utilization of computed tomography (CT) for patients with Crohn’s disease as patients are frequently diagnosed at a relatively young age and require repeated imaging. Between seven and eleven percent of patients with IBD are exposed to high cumulative effective radiation doses (CEDs) (>35–75 mSv), mostly patients with Crohn’s disease (Newnham E 2007, Levi Z 2009, Hou JK 2014, Estay C 2015). This is primarily due to the more widespread and repeated use of CT, which accounts for 77% of radiation dose exposure amongst patients with Crohn’s disease (Desmond et al., 2008). Reports of the projected cancer risks from the increasing CT use (Berrington et al., 2007) have led to increased patient awareness regarding the potential health risks from ionizing radiation (Coakley et al., 2011). Our responsibilities as physicians caring for these patients include education regarding radiation risk and, when an investigation that utilizes ionizing radiation is required, to keep radiation doses as low as reasonably achievable: the “ALARA” principle. Recent advances in CT technology have facilitated substantial radiation dose reductions in many clinical settings, and several studies have demonstrated significantly decreased radiation doses in Crohn’s disease patients while maintaining diagnostic image quality. However, there is a balance to be struck between reducing radiation exposure and maintaining satisfactory image quality; if radiation dose is reduced excessively, the resulting CT images can be of poor quality and may be nondiagnostic. In this paper, we summarize the available evidence related to imaging of Crohn’s disease, radiation exposure, and risk, and we report recent advances in low-dose CT technology that have particular relevance.

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