Estimation of Radiation Dose in Ct Venography of the Lower Extremities: Phantom Experiments Using Different Automatic Exposure Control Settings and Scan Ranges

Inoue, Yusuke; Itoh, Hiroyasu; Nagahara, Kazunori; Takahashi, Yōko

doi:10.1093/rpd/ncz265

Cited by 4 publications

(5 citation statements)

References 32 publications

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“…In the modification to the S3 condition, the abdomen was excluded from the scan range, and the modulation strength was intensified. While excluding the abdomen should increase %distal DLP, stronger modulation should decrease the relative contribution of the thin lower extremities (Inoue et al 2020). These two effects appeared to cancel each other out, resulting in similar %distal DLP, and consequently in similar %error and ED/DLP.…”

Section: Discussionmentioning

confidence: 88%

“…A previous phantom study demonstrated that the simplified method of ED estimation, i.e. multiplication of total DLP by the conversion factor for the trunk, overestimates ED in CT venography of the lower extremities (Inoue et al 2020). In the present study, we compared ED values estimated by the simplified and standard methods using actual patient data, and assessed the degree of overestimation in relation to the imaging conditions.…”

Section: Discussionmentioning

confidence: 92%

“…However, radiation exposure to the middle and distal portions of the lower extremities contributes to the DLP of CT venography. A previous phantom study simulating CT venography demonstrated that the contribution of such exposure to DLP is substantial, while its contribution to ED is negligible, and that ED is greatly overestimated when using the conversion factor for the trunk (Inoue et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

et al. 2022

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For radiation dose assessement of computed tomography (CT), effective dose (ED) is often estimated by multiplying the dose-length product (DLP), provided automatically by the CT scanner, by a conversion factor. We investigated such conversion in CT venography of the lower extremities performed in conjunction with CT pulmonary angiography. The study subjects consisted of eight groups imaged using different scanners and different imaging conditions (five and three groups for the GE and Siemens scanners, respectively). Each group included 10 men and 10 women. The scan range was divided into four anatomical regions (trunk, proximal thigh, knee and distal leg), and DLP was calculated for each region (regional DLP). Regional DLP was multiplied by a conversion factor for the respective region, to convert it to ED. The sum of the ED values for the four regions was obtained as standard ED. Additionally, the sum of the four regional DLP values, an approximate of the scanner-derived DLP, was multiplied by the conversion factor for the trunk (0.015 mSv/mGy/cm), as a simplified method to obtain ED. When using the simplified method, ED was overestimated by 32.3%−70.2% and 56.5%−66.2% for the GE and Siemens scanners, respectively. The degree of overestimation was positively and closely correlated with the contribution of the middle and distal portions of the lower extremities to total radiation exposure. ED/DLP averaged within each group, corresponding to the conversion factor, was 0.0089−0.0114 and 0.0091−0.0096 mSv/mGy/cm for the GE and Siemens scanners, respectively. In CT venography of the lower extremities, ED is greatly overestimated by multiplying the scanner-derived DLP by the conversion factor for the trunk. The degree of overestimation varies widely depending on the imaging conditions. It is recommended to divide the scan range and calculate ED as a sum of regional ED values.

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Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

et al. 2022

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“…In CT angiography and CT venography of the lower extremities, although irradiation to the lower extremities contributes significantly to DLP, the contribution to the effective dose is limited because of the low radiosensitivity of the lower extremities. Application of the conversion factor for the trunk leads to a severe overestimation of the effective dose [ 29 , 30 ].…”

Section: Overview Of Ct Radiation Dose Managementmentioning

confidence: 99%

Radiation Dose Management in Computed Tomography: Introduction to the Practice at a Single Facility

Inoue

2023

Tomography

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Although the clinical benefits of computed tomography (CT) are undoubtedly high, radiation doses received by patients are also relatively high; therefore, radiation dose management is mandatory to optimize CT radiation doses and prevent excessive radiation events. This article describes CT dose management practice at a single facility. Many imaging protocols are used in CT depending on the clinical indications, scan region, and CT scanner; thus, managing the protocols is the first step for optimization. The appropriateness of the radiation dose for each protocol and scanner is verified, while answering whether the dose is the minimum to obtain diagnostic-quality images. Moreover, examinations with exceptionally high doses are identified, and the cause and clinical validity of the high dose are assessed. Daily imaging practice should follow standardized procedures, avoiding operator-dependent errors, and information required for radiation dose management should be recorded at each examination. The imaging protocols and procedures are reviewed for continuous improvement based on regular dose analysis and multidisciplinary team collaboration. The participation of many staff members in the dose management process is expected to contribute to promoting radiation safety through increased staff awareness.

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“…However, CT examinations for deep vein thrombosis and lower limb arteriosclerosis obliterans may involve a scan ranging from the torso to the lower limbs. In this case, the CTDI vol (z), Dose Length Product (DLP), and effective dose have been used as patient dose indices [9][10][11][12]. The f-factor (DLP to effective dose conversion factor) for the lower limbs is not expressed in the International Commission on Radiological Protection (ICRP) publication 102 [13], but several studies have been reported [14,15].…”

Section: Introductionmentioning

confidence: 99%

SIZE-specific dose estimate for lower-limb CT

et al. 2022

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The Computed Tomography Dose Index (CTDI) is an indicator for dose management in computed tomography (CT), but has limited use for patient dosimetry. To evaluate the patient dose, the size-speci c dose estimate (SSDE), reported by the American Association of Physics in Medicine task groups 204, 220, and 293, must be calculated by the CTDI vol (z) displayed on the CT console and the conversion factor f(D(z)) from the effective diameter (D Eff ) or water equivalent diameter (D w ). However, no reports have veri ed the appropriateness of using the 320-mm diameter phantom for dose assessment in CT examinations involving the lower limbs. Therefore, we validated a new method for evaluating the SSDE(z) of the lower limbs, using two 160-mm diameter phantoms instead of the 320-mm diameter phantom. The CTDI vol (z) obtained from Monte Carlo (MC) simulation study was reliable because they were almost the same as obtained in a dosimetry study. The conversion factor f (D (z l.l .)) for the lower limbs was evaluated based on the CTDI vol (z) obtained by MC simulation performed using two polymethyl methacrylate cylinder phantoms of 160-mm diameter. The MC simulation was performed by the International Commission on Radiological Protection publication 135 reference adult phantom and was used to evaluate the absorbed dose of the pelvis, lower limbs, knees, and ankles. The dose showing the greatest difference was the lower limbs, which was 8.3 mGy (16%) lower than the absorbed dose. Thus, the SSDE (z l.l .) could be estimated from the CTDI 320 vol (z) displayed on the CT scanner console.

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Estimation of Radiation Dose in Ct Venography of the Lower Extremities: Phantom Experiments Using Different Automatic Exposure Control Settings and Scan Ranges

Cited by 4 publications

References 32 publications

Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

Radiation Dose Management in Computed Tomography: Introduction to the Practice at a Single Facility

SIZE-specific dose estimate for lower-limb CT

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