Patient Exposure Dose Research Articles

A Whole-Spine Radiography Study to Reduce Patient Exposure Dose and Artifacts Using the EOS Imaging System.

Whole-spine radiography can be accomplished through two methods: (1) segmented imaging employing X-ray tube angulation and detectors, or (2) the Euronext Paris Advanced Orthopedic Solutions (EOS) 2D Imaging system that can capture the entire spine in a single image using X-ray tubes and detectors oriented at a 90-degree angle. This study aimed to establish optimal EOS examination parameters based on patient morphotype and scan speed to reduce patient radiation exposure, repeat examinations, heat stress on equipment, and X-ray tube cooling time. X-ray exposure conditions involved adjustments of scan speed ranging from two to four steps, contingent upon the patient's morphotype ('S', small body; 'M', medium body; and 'L', large body. Patient dose measurements were conducted 20 times for each set of conditions. When transitioning from an 'S' to an 'M' morphotype at a constant scan speed, the entrance skin dose (ESD) exhibited an increase of approximately 41.25 ± 4.57%. A similar change from an 'M' to an 'L' morphotype resulted in an ESD increase of roughly 59.56 ± 24.00%. A transition from an 'S' to an 'L' morphotype at the same scan speed manifested an ESD elevation of approximately 124.21 ± 26.96%. This study underscores significant variations in radiation dose, ranging from 40% to 50%, when altering morphotype while maintaining a consistent scan speed.

Evaluation of Patient Exposure Dose during Cardiac Electrophysiology Study under Various Conditions

Evaluation of Patient Exposure Dose during Cardiac Electrophysiology Study under Various Conditions

Simultaneous percutaneous microwave ablation and biopsy for highly suspected malignant pulmonary nodules: a retrospective cohort study.

The conventional diagnosis and treatment for highly suspected malignant pulmonary nodules (PNs) can avoid unnecessary treatment to some extent. However, the relatively separate puncture processes may not only increase puncture-related complications, but also increase the patient's radiation exposure and hospitalization costs. The purpose of this study was to retrospectively analyze the effectiveness of simultaneous percutaneous microwave ablation (MWA) and percutaneous biopsy (PB) for PNs. From August 2015 to August 2022, 65 consecutive patients [48 solid nodules, 6 ground glass opacities (GGOs), 11 mixed nodules] with suspected single malignant PN underwent MWA and PB combination treatments at the First Affiliated Hospital of Zhengzhou University. The total of 30 patients in Group A underwent synchronous PB and MWA (strategy: low-power MWA-PB-high-power MWA), whereas 35 patients in Group B underwent asynchronous PB and MWA. The technical success, complete ablation (CA), complications, total procedure time (TPT), patient exposure dose (PED), hospitalization time, and costs were compared. An independent samples t-, χ2, or Fisher's exact tests were used. The technical success (100% vs. 100%) and CA (100% vs. 97.1%) rates were not significantly different between Groups A and B. The complications of intrapulmonary hemorrhage (16.7% vs. 41.4%, P=0.02) and hemoptysis (0% vs. 8.6%, P=0.04) were significantly different between Groups A and B. TPT (41.6±7.9 vs. 57.3±8.8 min, P<0.001), PED (12.9±1.4 vs. 19.4±2.3 mSv, P<0.001), hospitalization stay (4.7±1.3 vs. 9.1±2.1 days, P<0.001) and costs (3,768.8±652.9 vs. 4,508.0±514.1 USD, P<0.001) also showed significant differences between Groups A and B. Synchronous PB and MWA for PNs is a safe and effective strategy that can decrease bleeding, PED, the hospitalization stay, and costs.

Determination of Radiation Exposure of Individuals in the Population by Patients after Radioiodine Therapy - Comparison of two Measurement Systems.

In 147 patients after RIT and their relatives, the dosage was measured over 14 days with different measuring systems. Finger ring dosimeters (FRD) were worn during the whole day, furthermore the dose was determined by non-official OSL and TLD dosimeters during the sleep phase. 88 data sets were used for the final analysis. With the FRD, dose values between 0.1-50 mSv were determined for the patients. As expected, the finger ring dose of the relatives was significantly lower, averaging 0.75 mSv compared to 10 mSv for the patient. For the TLD and OSL used in the sleep phase, the measured values were in the same range. The reproducibility of the measurement results was significantly better for the OSL than for the TLD. Despite method-related measurement uncertainties, it can be concluded that the exposure dose of patients' relatives after radioiodine therapy is low and that the legal requirements are met. Moreover, the now official OSL dosimeters represent a more accurate and for the chosen measurement task better suited measurement system than the TLD. · The exposure dose of patients' relatives after radioiodine therapy is low.. · The requirements of radiation protection legislation after discharge from the nuclear medicine therapy ward are complied with. · OSL dosimeters are a accurate and for the measurement task suited system. · Hartmann H, Andreeff M, Claußnitzer J et al. Determination of Radiation Exposure of Individuals in the Population by Patients after Radioiodine Therapy - Comparison of two Measurement Systems. Fortschr Röntgenstr 2023; 195: 605 - 612.

Preoperative Dyeing Technique for Decreasing Radiation Exposure in Unilateral Biportal Endoscopic Spine Surgery

Minimally invasive surgery has many advantages, including early recovery and cosmetic preservation. However, the higher radiation exposure to physicians and patients has drawbacks. Preoperative tissue dyeing techniques are feasible options for reducing radiation exposure and procedure time, but their efficacy has not yet been evaluated. Therefore, this study aimed to evaluate surgical outcomes and reduce radiation exposure during unilateral biportal endoscopy surgery. This was a prospective, case-controlled analysis in a tertiary hospital. Patients receiving experimental tissue dye and controls in the nondye group were compared from May 2020 to September 2021. The ipsilateral posterolateral approach (IPA) and the far lateral approach (FLA) were analyzed separately among all single-level spinal procedures without instrumentation. Operative details (operation time, improvement of back and leg pain, and length of hospital stay) and radiation exposure (dose and duration) were compared. A total of 88 cases were included, consisting of 64 interlaminar approaches (experimental: 33, control: 31) and 24 FLAs (experimental: 13 and control: 11). In the IPA approach, the patient and physician radiation exposure doses and duration decreased significantly. Conversely, for the FLA, only the duration of the physician exposure decreased significantly. Preoperative tissue dyeing techniques using IPA can reduce radiation exposure for physicians and patients. However, a decrease in the duration of radiation was observed only in physicians using the FLA. The dyeing technique is effective in IPA, but the efficacy of FLA is doubtful.

Lung Ultrasound in ICU Admitted COVID-19 Patients; Can LUS Replace CT Chest

Patients with coronavirus disease (COVID-19) can develop severe bilateral pneumonia leading to respiratory failure. We aimed to study the value of lung ultrasound (LUS) in patients with COVID-19 admitted to ICU, in diagnosing pneumonia and predicting of prognosis of patients in comparison with CT chest, aiming to decrease the radiation exposure dose of patients during the disease from CT chest.

Nasolacrimal Duct Obstruction Secondary to Radioactive Iodine-131 Therapy for Differentiated Thyroid Cancer

Deterministic effects of medical exposure to ionising radiation can be associated with both the effectiveness of treatment and adverse drug reactions to it. The latter may drastically deteriorate the quality of life of a patient after radionuclide therapy. In addition, the regulations of the Russian Federation require indicating the effective dose of radiation as a measure of damage (risk), but the presence of a deterministic effect in individual organs and tissues complicates monitoring and recording patient exposure doses. The aim of the study was to investigate the effect of radiopharmaceuticals containing 131 I on the development of secondary nasolacrimal duct obstruction (NLDO). Materials and methods : the study of secondary NLDO predictors analysed medical history data, post-therapy head-and-neck scintigrams, and methods to prepare patients for treatment. It involved sodium iodide, 131 I, formulated as a solution (marketing authorisation number: FS-002065) by the FSUE Federal Center of Nuclear Medicine Projects Design and Development of the FMBA of Russia. Results : the authors unambiguously localised the lacrimal ducts in post-therapy 131 I scintigrams of the head and neck and quantified 131 I uptake ratios for the lacrimal duct area. Also, they identified a set of NLDO predictors: the age of a patient, the administered activity, the administration of recombinant human thyroid-stimulating hormone, the 131 I uptake ratio, etc. The article describes a method for identifying the groups at risk of NLDO following radioiodine therapy for differentiated thyroid cancer. Conclusions : secondary NLDO is a deterministic effect of 131 I exposure. The authors have developed a new method for predicting secondary NLDO by a combination of the patient’s individual parameters and treatment plan; the identified predictors help to personalise radioiodine therapy. The authors suggest the following: to include information on secondary NLDO as a complication of therapy to the SmPC section on undesirable effects; to develop approaches to secondary NLDO prevention; and to improve the algorithms for reporting adverse events in case of delayed manifestation and those for following patients up in the medical organisations having administered the radiopharmaceutical or in other medical organisations being applied to for medical care afterwards.

Patient Exposure Dose Reduction in Coronary Angiography &amp; Intervention

Patient Exposure Dose Reduction in Coronary Angiography &amp; Intervention

Patient exposure dose in interventional cardiology per clinical and technical complexity levels. Part 1: results of the VERIDIC project.

Patients can be exposed to high skin doses during complex interventional cardiology (IC) procedures. To identify which clinical and technical parameters affect patient exposure and peak skin dose (PSD) and to establish dose reference levels (DRL) per clinical complexity level in IC procedures. Validation and Estimation of Radiation skin Dose in Interventional Cardiology (VERIDIC) project analyzed prospectively collected patient data from eight European countries and 12 hospitals where percutaneous coronary intervention (PCI), chronic total occlusion PCI (CTO), and transcatheter aortic valve implantation (TAVI) procedures were performed. A total of 62 clinical complexity parameters and 31 technical parameters were collected, univariate regressions were performed to identify those parameters affecting patient exposure and define DRL accordingly. Patient exposure as well as clinical and technical parameters were collected for a total of 534 PCI, 219 CTO, and 209 TAVI. For PCI procedures, body mass index (BMI), number of stents ≥2, and total stent length >28 mm were the most prominent clinical parameters, which increased the PSD value. For CTO, these were total stent length >57 mm, BMI, and previous anterograde or retrograde technique that failed in the same session. For TAVI, these were male sex, BMI, and number of diseased vessels. DRL values for Kerma-area product (PKA), air kerma at patient entrance reference point (Ka,r), fluoroscopy time (FT), and PSD were stratified, respectively, for 14 clinical parameters in PCI, 10 in CTO, and four in TAVI. Prior knowledge of the key factors influencing the PSD will help optimize patient radiation protection in IC.

Examination of Exposure Dose by Procedure in Cerebral Angiography

In cerebral angiography, the patient's exposure dose varies greatly depending on the target site, purpose, and difficulty of the procedure. Therefore, it is necessary to manage the dose based on not only the disease but also the procedure. In this study, diagnostic cerebral angiography (diagnosis group) was classified into 13 procedures and neuro-interventional radiology (treatment group) was classified into 10 procedures, and the total dose, fluoroscopy dose, radiographic dose, fluoroscopy time, and number of radiographic frames were compared. For each item, the treatment group was significantly higher than the diagnosis group, but for some, the diagnosis group exceeded the median of treatment group. For the diagnosis group, the total irradiation time and fluoroscopy time were significant, and for the treatment group, all the items showed significant differences due to differences in procedures, and there were also cases where the same disease had differences due to procedures. To manage patient exposure in cerebral angiography, it is necessary to manage the usage rate and dose of fluoroscopy and radiography. In addition, it is important to evaluate, manage, and optimize the total dose, fluoroscopic dose, and radiographic dose for each procedure in not only the treatment group but also the diagnosis group.

A RADIOLOGIA ODONTOLÓGICA DIGITAL NO ESQUADRÃO DE SAÚDE DE FLORIANÓPOLIS: RELATO DE CASO

O presente artigo relata como foi implementada a Radiologia Digital na Seção de Odontologia do Esquadrão de Saúde de Florianópolis (ES-FL). O objetivo foi a necessidade de modernização dos equipamentos de radiodiagnóstico odontológico existentes, tornando-os digitais. Para tanto, foram analisadas as opções de sistemas digitais existentes e as vantagens dos sistemas CMOS (Complementary Metal Oxide Semiconductor) e PSP (Photostimulable Phosphor Plate), considerando-se, além de seus aspectos técnicos, também os aspectos de biossegurança, de sustentabilidade e jurídicos. Após análise dos dados e comparação dos preços encontrados por intermédio de processo licitatório, optou-se pelo sistema PSP, que apresentava maior vantajosidade. Constatou-se que a implantação da Radiologia Digital no ES-FL trouxe inúmeras vantagens aos pacientes e profissionais da instituição, tais como a diminuição na dose de exposição do paciente, a possibilidade de manipulação das imagens para aprimorar o diagnóstico, a facilidade de comunicação com os pacientes e entre profissionais, além do impacto ambiental positivo, atendimento célere aos pacientes e radioproteção ao usuário, ao profissional e à equipe.

Определение лучевой нагрузки на пациентов при стоматологических рентгенологических исследованиях

Purpose: Improving the quality of radiation assessment of patients of the medical institution of the dental profile using the calculated values of effective doses.&#x0D; Material and methods: Using the RED-2018 and ORTO-2018 programs, the values of effective patient exposure doses for 29 medical organizations of the dental profile were calculated. The obtained values of the effective dose were compared with the values specified in the methodological recommendations MP 0100 / 1659-07-26 of February 16, 2007 “Filling of forms of federal state statistical observation 3-DOZ”.&#x0D; Results: The analysis showed that the doses obtained using the RED-2018 and ORTO-2018 computer programs, respectively, are 21 and 14 times lower than the doses indicated in the methodological recommendations MP 0100 / 1659-07-26. &#x0D; Conclusion: It is shown that the developed computer programs can be applied by a dentist practicing physician who performs an x-ray examination in order to automatically and reliably determine the patient’s dose when performing x-ray-mathematical studies in accordance with the guidelines of MU 2.6.1.2944-11 “Monitoring effective doses of patients during x-ray examinations” also used in the preparation of radiation hygienic passports of organizations and statistical form 3-DOZ. The indication of the actually calculated values of the effective dose of the patient, rather than repeatedly overestimated averages, will reduce the level of radiophobia in society.

A Comparison of Density and Patient Doses According to kVp and mAs Changes in General Radiography

Low energy x-rays that occur in the low tube voltage radiography of general radiography are absorbed strongly in the body and do not aid image quality enhancement. This study maintains titer in general radiography while using tube current that are proportional to density and the tube voltage 15% principle according to density to reduce patient exposure doses, and area doses and entrance surface doses were measured to compare patient exposure doses. In hand, knee, abdomen, and skull radiography, kVp was increased to 115% and mAs was decreased to 50% and kVp was decreased to 85% while mAs was increased to 200% and area doses and entrance surface doses were measured to compare relative doses. Also, 5 places in each image were set, density was measured, and Kruskal wallis H test was conducted to observe significance probabilities between groups. To fix density, kVp was increased to 115% and mAs was decreased to 50% and after measurements of mean area doses and entrance surface doses were made by each part, each decreased to 58.68% and 59.85% when standard doses were set to 100%, and each increased to 147.28% and 159.9% when kVp was decreased to 85% and mAs was increased to 200%. Comparisons of density changes showed that hand, knee, abdomen, and skull radiography all displayed significance probabilities>0.05, showing no changes in concentration. Radiography that increases kVp and lowers mAs through reasonable calculations within ranges that don’t affect resolution and contrast seems to be a simple way to decrease patient exposure doses.

Effectiveness of additional X-ray protection devices in reducing Scattered radiation in radial interventions: protocol of the ESPRESSO randomised trial

BackgroundA number of devices have been developed to minimise operator radiation exposure in the setting of cardiac catheterisation. The effectiveness of these devices has traditionally been explored in transfemoral coronary...

Evaluation of Usefulness of the Half Scan in CT Guided Interventional Radiology

목적: 최근 CT를 이용한 중재적 시술이 증가함에 따라 환자 및 시술자의 피폭선량도 증가하는 추세이다. 본 연구에서는 CT를 이용한 중재적 시술에서 전체스캔(Full Scan, 이하 FS) 과 절반스캔(Half Scan, 이하 HS)의 환자 및 시술자의 피폭선량과 화질의 평가를 통해 HS의 유용성을 확인하고자 하였다. 대상 및 방법: T 사의 Aquilion One Genesis CT를 사용하였으며, PMMA 아크릴 팬텀과 CT 전용 전리조 시스템을 이용하여 FS과 X-선의 노출 방향을 상,하,좌,우로 선택이 가능한 HS 의 피폭선량을 비교하였다. 이때 조건은 FS 120 mA, HS 180 mA, 예측선량은 5.60 mGy로 동일하게 한 후 스캔하였다. 시술자의 공간선량 측정은 전리조를 이용하여 갠트리 중심부에서 좌, 우 1.00 m 지점(지상으로부터 1.00 m 높이)의 지점에서 선량을 측정하였다. 화질평가를 위해서 ACR 팬텀의 영상을 획득한 후, CT number 와 잡음 그리고 균일도를 비교하였다. 결과: 피폭선량을 측정한 결과, FS 5.53 mGy, HS의 네 방향 평균 5.53 mGy로 예측선량(5.60 mGy)과 0.07 mGy의 차이를 나타냈으며 유의한 차이를 보이지 않았다(p>0.05). 시술자 위치의 공간선량을 평가한 결과, HS 이용 시 X-선 노출의 반대 측 시술자 선량은 FS에 비해 8.7~9.6% 감소됨을 알 수 있었다(p<0.05). ACR 팬텀을 이용하여 측정된 물의 CT number값은 FS에 비해 HS에서 0 HU에 근접된 값을 나타내었으며, 잡음은 FS이 24.03±0.50 HU로 측정되었으며, HS(네 방향 평균)은 22.15±0.54 HU로 FS에 비해 유의하게 적었다(p<0.05). 그리고 균일도의 경우 FS이 -1.58±0.39 HU로 측정되었으며 HS의 네 방향 평균은 0.35±0.48 HU로 FS에 비해 유의하게 적었다(p<0.05). 결론: HS과 FS의 화질을 평가한 결과, HS이 FS에 비하여 우수하였다. 그리고 시술자의 위치에 따라 HS 기법의 X-선 조사방향을 적절하게 선택하면 피폭선량을 감소시킴을 알 수 있었다. 따라서 CT를 이용한 중재적 시술에서 HS 기법은 유용성에 매우 높을 것이라 사료된다.Purpose: As the CT guided interventional radiology increase so does the exposure dose of patients and workers. The usefulness of half scan (HS) compared to full scan (FS) was assessed in terms of the exposure dose of patient and the image quality in CT guided interventional radiology. Materials & Method: The patient dose of FS and HS were measured by using the PMMA acrylic phantom and ionization chambers in CT (Aquillon one genesis, Toshiba); the data was converted to CTDI vol . The predicted dose of HS and FS kept as 5.60 mGy by setting X-ray tube current as 120 mA and 180 mA for FS and HS, respectively. Spatial dose distribution of workers was measured at the left and right points 1.0-m from the center of the gantry using a lower-level radiation protection chamber which located 1.0-m above the ground. The image quality was evaluated from the CT number, noise, and uniformity of ACR phantom. Result: The measured exposure dose of the full scan and the average of half scan were same as a 5.53 mGy. Discrepancy between the measured and the estimated dose was 0.07 mGy and did not show any significant difference (p>0.05). The spatial dose of workers in half scan at the opposite side of X-ray exposure is lower than that of full scan by 8.7-9.6% (p<0.05). The CT number of waters is closer to 0 HU in half scan than full scan. Noise of the full scan and the half scan were 24.03±0.50 HU and 22.15±0.54 HU, respectively. Also, the uniformity of the full scan and the half scan were -1.58±0.39 HU and 0.35±0.48 HU, respectively. The noise and uniformity in half scan were the average value of four directions. Conclusion: In summary, the image quality of half scan is better than that of half scan. Also, the exposure dose of workers can be reduced by the selection of proper X-ray exposure direction; therefore, the half scan is useful technique in the CT guided interventional radiology.

Optimization of Radiation Dose and Image Quality using ADMIRE Algorithm and Quantitative Evaluation

목적: 최신 반복적 재구성법인 ADMIRE 알고리즘을 물질의 종류, 검사 조건, 적용 단계에 관하여 정량적으로 평가하고 이를 활용하여 환자 피폭선량과 영상의 질을 최적화 하고자 한다. 대상 및 방법: 증류수와 조영제의 혼합용액으로 밀도가 다른 네 종류의 물질 A(30~40 HU), B(60~70 HU), C(100~110 HU), D(200~210 HU)를 제작하여 AAPM phantom의 저 대조도 측정 부위에 주입하였다. 100, 120 kVp 두 종류의 관전압과 250~ 50 mAs 관전류로 선량을 50 mAs 단위로 감소시켜 영상을 획득하고 FBP와 1~5단계의 ADMIRE를 적용하여 CT number, SNR, CNR을 정량적으로 평가하였다. 결과: CT number(HU)값은 FBP와 ADMIRE의 적용 단계에 따라서는 차이가 없었고(P>0.05), 120 kVp와 비교하여 100 kVp를 사용하였을 경우 23±2%(P<0.05) 증가하였다. SNR은 ADMIRE를 1~5단계까지 순차적으로 적용하였을 경우 각각 10%, 23%, 38%, 60%, 98% 증가하였고, CNR은 10%, 22%, 36%, 58%, 97% 증가하였다. 120 kVp, 200 mAs, FBP영상을 기준으로 선량이 150 mAs(75%), 100 mAs(50%), 50 mAs(25%)로 감소하였을 때, 영상의 질을 유지하기 위해서는 1, 3, 5단계 이상의 ADMIRE 적용을 필요로 하였다. 결론: ADMIRE를 적용할 경우 영상의 질 저하 없이 최대 75%의 선량감소 효과를 기대할 수 있으며, 50%이상의 선량을 감소시켰을 경우에는 3단계 이상의 ADMIRE적용을 필요로 한다.Purpose: The ADMIRE algorithm which is the latest iterative reconstruction (IR) was quantitatively evaluated depending on the type of substances, scan parameter, and the stages of application to optimize patient exposure dose and image quality. Material and method: The four different types of substances; A(30~40 HU), B(60~70 HU), C(100~110 HU), and D(200~210 HU), were manufactured by using mixture of water and contrast medium and injected into the hole of the low contrast measuring part of AAPM phantom. The signal to noise ratio (SNR) and contrast to noise ratio (CNR) were quantitatively evaluated with CT numbers depending on the two types of tube voltage(100, 120 kVp), the five types of tube current by reducing the dose to 50 mAs(250, 200, 150, 100, 50 mAs), and the five types of algorithms (FBP, 1 to 5 steps in ADMIRE). Result: There were no significant differences of CT number (HU) among images depending on the application phase of FBP and ADMIRE algorithms(p>0.05); however, HUs with 100 kVp were increased up to 23±2% compared to 120 kVp(p<0.05). SNR was increased by 10%, 23%, 38%, 60%, and 98% when ADMIRE algorithms were applied sequentially to steps 1 to 5. Also, CNR was increased by 10%, 22%, 36%, 58%, and 97% in the same ADMIRE algorithm condition. Equal quality of filtered back projection (FBP) image taken with 120 kVp and 200 mAs, was maintained by applying more than 1, 3, and 5 strengths of ADMIRE in case of 150 mAs(75%), 100 mAs(50%), and 50 mAs(25%) patient dose reduction. Conclusion: ADMIRE can reduce patient dose up to 75% without degradation of image quality. In addition, the application of ADMIRE more than 3 strengths are required if the patient dose reduced by more than 50%.

Chronic low dose exposure of hospital workers to ionizing radiation leads to increased micronuclei frequency and reduced antioxidants in their peripheral blood lymphocytes

Purpose: The regular low dose occupational exposure to ionizing radiation may induce deleterious health effects, which may be of particular interest to medical radiation workers who daily handle X-ray machines. Human peripheral blood lymphocytes are able to retain the signature of radiation-induced DNA damage, therefore, the present study was undertaken to investigate the DNA damage and antioxidants status in hospital workers occupationally exposed to low doses of X-rays.Materials and methods: The peripheral blood lymphocytes of the occupationally exposed and control groups matched for age, gender, tobacco usage, and alcohol consumption were cultured and micronuclei frequency was determined. Activities of antioxidant enzymes and lipid peroxidation were also estimated in their plasma.Results: The micronuclei frequency in the occupationally exposed group (n = 33), increased significantly (p < .0001) followed by reduced glutathione-s-transferase (p < .01) and catalase (p < .001) activities, and increased lipid peroxidation (p < .05) when compared to the control group (n = 33). Occupational exposure resulted in an effective dose ranging between 3.14 to 144.5 mSv (40.88 ± 39.86mSv) depending on the employment duration of 3–29 years (10.33 ± 7.05 years). A correlation between the micronuclei frequency (p < .05) and catalase activity (p < .05) existed in the occupationally exposed individuals depending on the smoking habit, age, duration of employment, cumulative exposure dose and number of patients handled per day.Conclusions: We have observed that protracted low dose exposure to ionizing radiation is an inevitable occupational hazard leading to persistence of oxidative stress and increased genomic instability in the radiological technicians depending on the time spent with X-rays, cumulative dose received and the number of patients handled daily raising the risk of cancer development.

Effect of different exposure times on caries detection and pixel value in a wireless digital system.

: The aim of this study was to assess, using the CDR Wireless®, the effect of different exposure times on caries detection and pixel intensity values. Forty teeth were x-rayed using a Schick CDR Wireless sensor at eight different exposure times - 0.06, 0.10, 0.13, 0.16, 0.20, 0.25, 0.30, and 0.32 s. Four observers evaluated the images for presence of carious lesions scoring proximal surfaces of each tooth on a 5-point scale. Scores were compared to histological sections of the teeth. Accuracy was evaluated by means of ROC curve analysis. Radiographs of an aluminum step wedge were obtained using the same eight exposure times. Pixel intensity measurements were obtained, and mean pixel values were statistically analyzed using linear regression. The Az for each exposure time varied from 0.53 to 0.62. Two-way analysis of variance and Tukey test demonstrated that the exposure time of 0.25 s presented the best result and was significantly higher than 0.30 s and 0.35 s. In regard to mean pixel values, two different behaviors were observed, and the exposure time of 0.20 s presented mean pixel values in both phases. The performance of the exposure times from 0.06 s to 0.25 s was satisfactory for proximal caries detection, and 0.25 s is the best as indicated for this finality. Considering that a reduction of exposure time represents a reduction of patient exposure dose, and this reduction cannot neglect image quality, the behavior of any digital system must be carefully evaluated.

Investigation of shutter scan acquisition parameters in a prototype chest digital tomosynthesis system

A shutter scan acquisition (SSA) method is proposed to reduce patient exposure dose in a chest digital tomosynthesis system. Projections obtained using the SSA constitute a combination of truncated and non-truncated projections. The truncated projections are images in which the lung field is set within a region-of-interest (ROI), and the non-truncated projections are full images in which the ROI is not set at all. We proposed a shutter weighting factor (SWF) as an acquisition parameter for SSA. We call the number of truncated projections divided by the number of non-truncated projections as SWF. We used a prototype CDT system and the LUNGMAN phantom with 8 and 10 mm lung nodules. 81 projections were obtained using SSA in five sets according to the SWFs. The image quality was quantified based on the contrast-to-noise ratio (CNR). We also calculated the figure of merit (FOM) to determine the proper acquisition parameters of the five sets. Both the CNR and FOM values of the 8 mm lung nodule in the selected ROI increased with increases of the SWF. However, the CNR value of the 10 mm lung nodule outside the ROI decreased with increases of the SWF, while the FOM value was maximized when the SWF was 3.05. We investigated the effect of the composition ratio of the truncated and non-truncated projections on the reconstructed images of the SSA based on the FOM values. In conclusion, we determined the proper SSA parameters in a prototype CDT system.

Comparison study of various beam modulation schemes on image quality in chest digital tomosynthesis (CDT) system

Recently, digital tomosynthesis systems have been actively investigated to reduce radiation dose in medical imaging. In this work, we present various beam modulation schemes for low-dose digital tomosynthesis; we compared the effects of the various acquisition schemes on image quality. A prototype chest digital tomosynthesis (CDT) system (LISTEM, Korea) and the LUNGMAN phantom (Kyoto Kagaku, Japan) with lung nodules were used in this study. A total of 81 projection data obtained through various beam modulation schemes over a 40° angular range were reconstructed using the filtered back projection (FBP) algorithm. The contrast noise ratio (CNR), structural similarity index (SSIM), and peak signal-to-noise ratio (PSNR) of the lung nodules were calculated to evaluate the image quality depending on the acquisition scheme. The reconstructed images obtained based on the proposed beam modulation schemes showed enhanced contrast in addition to a reduction of the area dose. It was determined that the beam modulation schemes affect the image quality. Among beam modulation schemes we investigated, the bunched view acquisition (outer focused) showed promising results within the region of interest (ROI). The reconstructed image obtained using the bunched view showed an increase of the CNR value by 63% compared to the conventional acquisition method. In addition, shutter scan acquisition showed promising results for the restoration information for the outside ROI. We determined that the beam modulation schemes in the prototype CDT system affect the image quality. It is also expected that the patient exposure dose can be reduced by modulating the beam size in the prototype CDT system.