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

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.

Whole-body biodistribution and radiation dosimetry of [18F]PR04.MZ: a new PET radiotracer for clinical management of patients with movement disorders

Purpose [18F]PR04.MZ is a new PET imaging agent for dopamine transporters, providing excellent image quality and allowing for the evaluation of patients with movement disorders such as Parkinson’s disease. The objective of this study was to evaluate the biodistribution and radiation dosimetry of [18F]PR04.MZ by serial PET imaging. Methods Six healthy subjects (n = 3 males, n = 3 females) were enrolled in this study. A series of 14 whole-body PET/CT scans were acquired until 5.5 h post-injection of 200 ± 11 MBq of [18F]PR04.MZ. After rigid co-registration, volumes of interest were outlined either on CT or PET images. Time-integrated activity coefficients were calculated for selected source organs. Organ absorbed doses, and the effective dose were calculated using IDAC-Dose 2.1. Results Physiological uptake of [18F]PR04.MZ was mainly observed in the striatum, brain, liver, gall bladder, intestine, red marrow and cortical bone. [18F]PR04.MZ was primarily excreted via hepatobiliary clearance and, to a lower extent, via renal clearance. The normalized absorbed doses were highest in gall bladder wall (32.2 ± 6.4 µGy/MBq), urinary bladder wall (27.2 ± 4.5 µGy/MBq), red marrow (26.5 ± 1.4 µGy/MBq), cortical bone surface (26.3 ± 2.5 µGy/MBq), liver (22.5 ± 1.8 µGy/MBq) and kidneys (21.8 ± 1.1 µGy/MBq). The effective dose according to ICRP 60 and 103 was 16.3 ± 1.1 and 16.6 ± 1.5 µSv/MBq, respectively. Conclusion [18F]PR04.MZ has a favourable dosimetry profile, comparable to those of other 18F-labelled PET tracers, and is suitable for larger clinical applications. Trial registration CEC SSM Oriente, Santiago, Chile, permit 20140520.

An algorithm for thoracic re-irradiation using biologically effective dose: a common language on how to treat in a “no-treat zone”

Background Re-irradiation (re-RT) is a technically challenging task for which few standardized approaches exist. This is in part due to the lack of a common platform to assess dose tolerance in relation to toxicity in the re-RT setting. To better address this knowledge gap and provide new tools for studying and developing thresholds for re-RT, we developed a novel algorithm that allows for anatomically accurate three-dimensional mapping of composite biological effective dose (BED) distributions from nominal doses (Gy). Methods The algorithm was designed to automatically convert nominal dose from prior treatment plans to corresponding BED value maps (voxel size 2.5 mm3 and α/β of 3 for normal tissue, BED3). Following the conversion of each plan to a BED3 dose distribution, deformable registration was used to create a summed composite re-irradiation BED3 plan for each patient who received two treatments. A proof-of-principle analysis was performed on 38 re-irradiation cases of initial stereotactic ablative radiotherapy (SABR) followed by either re-SABR or chemoradiation for isolated locoregional recurrence of early-stage non-small cell lung cancer. Results Evaluation of the algorithm-generated maps revealed appropriate conversion of physical dose to BED at each voxel. Of 14 patients receiving repeat SABR, there was one case each of grade 3 chest wall pain (7%), pneumonitis (7%), and dyspnea (7%). Of 24 patients undergoing repeat fractionated radiotherapy, grade 3 events were limited to two cases each of pneumonitis and dyspnea (8%). Composite BED3 dosimetry for each patient who experienced grade 2–3 events is provided and may help guide development of precise cumulative dose thresholds for organs at risk in the re-RT setting. Conclusions This novel algorithm successfully created a voxel-by-voxel composite treatment plan using BED values. This approach may be used to more precisely examine dosimetric predictors of toxicities and to establish more accurate normal tissue constraints for re-irradiation.

Assessment of Naturally Occurring Radionuclides Accumulation in Palm Oil from Soil

Hyper Pure Germanium (HPGe) radiation detector was used to estimate the activity concentration of fifteen soil and palm oil samples collected from the oil palm plantations in the southwestern, southeastern, and south southern states of Nigeria, and the risk assessments was evaluated. The activity concentrations at a soil depth 0 – 15 cm ranged from 187.4 to 514.4, 2.328 to 6.571, and 1.509 to 6.121 Bq/kg for 40K, 238U, and 232Th, respectively. The activity concentrations at a soil depth 15 – 30 cm ranged from 163.4 to 3188.8, 1.345 to 9.410, and 1.476 to 6.275 Bq/kg for 40K, 238U, and 232Th, respectively. The activity concentrations in the palm oil ranged from 122.3 to 968.0, 1.240 to 6.651, and 1.199 to 8.061 Bq/L for 40K, 238U, and 232Th. For the risk assessments of surface soil samples, the absorbed dose rate (D) ranged from 5.09 to 24.54 nGy/h, while the annual effective dose equivalent (E) ranged from 0.612 × 10-2 to 16.49 × 10-2 mSv/y. The radium equivalent, gamma absorbed dose rate, and the annual effective dose rate in the palm oil samples ranged from 9.981 to 88.00 Bq/L, 4.315 to 46.29 nGy/h, and 0.53 × 10-2 to 56.90 x 10-2 mSv/y, respectively. The activity concentrations reported for soil and palm oil samples were lower than the recommended world average values given by UNSCEAR. Hence, the hazard and risk assessments indicated a low radiation risk within the studied areas.

Uji Aktivitas Hepatoprotektor Ekstrak Etanol Daun Rambutan (Nephelium lappaceum L.) pada Mencit Putih Jantan yang Diinduksi Parasetamol

Hepatotoxicity is a drug complication that is often found in long-term drug use because of the role of the liver in metabolizing drugs. Paracetamol is an analgesic and antipyretic drug that is often used by the community and is a safe choice when taken according to the dose. However, if consumed in excess and in the long-term it causes hepatotoxicity (liver damage). Liver damage can be prevented by giving antioxidant compounds. Rambutan’s leaves contain secondary metabolites of alkaloids, tannins and saponins which are known to have antioxidant potential. The aim of the research is to determine the hepatoprotective activity and the effective dose of Rambutan leaves ethanol extract in male mice induced by patacetamol. The research method was The Randomize Posttest-only Control Group Design using 25 white mice which were divided into 5 groups. The results showed that there was a significant difference in the treatment group of rambutans leaf ethanol extract with the negative control group and a non-significant with the positive control group. Giving extract doses of 100 mg/kg BW, 200 mg/kg BW and 400 mg/kg BW because it prevents the increase in levels of SGPT, SGOT, relative liver weight and reduces the percentage of damage to the hepatocytes of mice. The effective dose of rambutan’s leaf ethanol extract as a hepatoprotector is 400 mg/kg BW.

INDOOR RADON-222 CONCENTRATION MEASUREMENTS AT FACULTY OF EDUCATION, YAFEA, ADEN UNIVERSITY, YEMEN, USING CR-39 NUCLEAR TRACK DETECTOR

In this study, the activity concentration of indoor radon-222, annual effective dose, exhalation rate of radon, and relative risk of lung cancer are reported for different indoor buildings (students' dorms, teachers' dorms, offices, laboratories, library, lecture halls, and materials store) in Faculty of Education, Yafea, Aden University, Yemen. Sealed-can technique based on CR-39 nuclear tracks detector was distributed to radon gas survey. Twenty six radon detectors were mounted in seven buildings. The Radon measurements were performed for 90 days between December 2020 and March 2021. The results showed that the radon concentration ranges from 23,18 Bq m-3 to 66.49 Bq m-3 with an average value 35.86 Bq m-3, the annual effective dose ranges from 0.6 mSv y-1 to 1.639 mSv y-1 with an average value 0.979 mSv y-1, the exhalation rate ranges from 10.03 m Bq m-2 h-1 to 28.50 mBq m-2 h-1 with an average value 15.68 mBq m-2 h-1 and relative risk of lung cancer ranges from 1.02 to 1.06 with an average value 1.03. A strong correlation coefficient has been observed between radon concentration and radon exhalation rate. All of the values revealed in the study were of nominal state (that is less than allowed global values) and thus have no risk for the population living in these buildings.

In vivo anti-inflammatory activity of rhizome of Drynaria quercifolia (L.) J. Sm.

Inflammation is found as a common pathogenic process in many of the chronic diseases. To manage them drugs having multiple active principles is needed. Here comes the importance of easily available, potent herbal medicines. Drynaria quercifolia (L.) J. Sm., is a medicinal fern and its rhizome is an ingredient of some Ayurvedic formulations with inflammation. Through present study in vivo analysis of powder (choorna) of the drug were done. Wistar Albino rats were used for the purpose. One group was control (no treatment) and the other three were treated groups given with the suspension of powdered drug in half the calculated effective dose (0.108 gm/200 gm b. Wt.), calculated effective dose (0.216gm/200 gm b. Wt.) and double the calculated effective dose (0.432 gm/200 gm b. Wt.). Repeated measures ANNOVA with Tukey’s post hoc analysis was used as statistical tool to analyse results within the group and one way ANNOVA with Tukey’s post hoc analysis was used for between group analysis. In all the three treated groups significant reduction in paw oedema noted at 2nd hour and maximum reduction at 4th hour after drug administration. But a highly significant reduction in paw oedema at shortest time after drug intake was produced by group administered with double the calculated effective dose of the drug. This showed dose dependent anti-inflammatory action of powder of rhizome of Drynaria quercifolia (L.) J. Sm. This activity can be due to the presence of anti-inflammatory phytoconstituents in the rhizome such as naringin, quercetin, friedelin, betasitosterol, etc.