Validation of Adult Relative Radiation Levels Using the ACR Dose Index Registry: Report of the ACR Appropriateness Criteria Radiation Exposure Subcommittee

The ACR Dose Index Registry (DIR) provides a new source of clinical radiation exposure data that has not been used previously to establish or update the relative radiation level (RRL) values in the ACR Appropriateness Criteria (AC). The results of a recent review of DIR data for 10 common CT examinations were compared with current ACR AC RRL values for the same procedures. The AC RRL values were previously determined by consensus of members of the AC Radiation Exposure Subcommittee based on reference radiation dose values from the literature (when available) and anecdotal information from individual members’ clinical practices and experiences. For 7 of the 10 examination types reviewed, DIR data agreed with existing RRL values. For 3 of 10 examination types, DIR data reflected lower dose values than currently rated in the AC. The Radiation Exposure Subcommittee will revise these RRL assignments in a forthcoming update to the AC (in October 2018) and will continue to monitor the DIR and associated reviews and analyses to refine RRL assignments for additional examination types. Given recent attention and efforts to reduce radiation exposure in CT and other imaging modalities, it is likely that other examination types will require revision of RRL assignments once information from the DIR database is considered.     

Needle position during (125)I seed implantation: accurately recognized by sagittal transrectal ultrasonography [corrected

Purpose  The aim of this study was to assess the variation of probe rotation angles for detecting a single needle using sagittal images of transrectal ultrasonography (TRUS). Materials and methods  A phantom study was performed. One needle was inserted through each of 10 holes of the template, and variations in the probe rotation angles for detecting the needle were measured. Results  The mean variation of probe rotation for detecting a single needle was 17.0° (range 4°–25°). Slightly broader variation was seen for the needle in holes farther away from the probe. Conclusion  Probe rotation angles for detecting a single needle displayed considerable variation. Seed locations recognized on sagittal imaging by TRUS are thus indeterminate, and real-time dose calculations using TRUS for ¹²⁵I seed implantation should be used with care.     

The impact of spleen volume on the survival of metastatic pancreatic adenocarcinoma patients receiving nanoliposomal irinotecan

Nanoliposomal irinotecan (nal-IRI) plus 5-fluorouracil and leucovorin (NalFL) comprises the current standard for gemcitabine-failed metastatic pancreatic ductal adenocarcinoma (PDAC). As liposomes generally accumulate in the spleen, we evaluated the impact of spleen volume on prognosis. We enrolled patients with metastatic PDAC who failed gemcitabine-based therapy and were initiated on NalFL between August 2018 and November 2020. The spleen volume before NalFL administration was evaluated. They were stratified into dose subgroups (i.e. low, < 48 mg/m²; intermediate, 48 - < 64 mg/m²; high, ≥ 64 mg/m²) by the average nal-IRI dose during the entire treatment, and multivariate analysis of overall survival (OS) was performed. We included 547 patients with a median age of 63 years (range, 27-89 years) and a median of 1 (range, 0-7) palliative chemotherapy regimen. The median spleen volume was 245 mL (range, 82-817 mL). Among patients with splenomegaly (≥ 245 mL), the low-dose subgroup had the worst median time to treatment failure (TTF, 1.8 months vs. 2.5 months vs. 2.5 months, P = 0.020) and OS (3.3 months vs. 5.9 months vs. 6.6 months, P = 0.018) as against no prognostic impact in patients without splenomegaly. In the multivariate analysis of patients with splenomegaly, performance status (PS) ≥ 2, body surface area (BSA) < 1.6 m², prior fluoropyrimidine use, liver metastasis, and low-dose subgroup were independent poor prognostic factors. A low average nal-IRI dose was significantly associated with poor prognosis, especially among patients with splenomegaly. Further pharmacological studies should validate the relevance of spleen volume on the treatment outcomes of nal-IRI.     

ECG管电流调制技术在大体重前瞻性冠脉CTA序列扫描中的剂量研究

目的大体重患者在冠脉CTA前瞻性序列扫描中运用ECG管电流调制技术评价X线吸收剂量及临床应用。方法40例体重指数(BMI)24的患者在冠脉CTA检查中随机分为两组:A组20例采用ECG管电流调制技术(ATCM),心率70次/分时,扫描范围为20%-80%R-R间期,设60%-80%R-R间期组为全剂量扫描范围;心率70次/分时,扫描范围为20%-80%R-R间期,设35%-55%R-R间期组为全剂量扫描。B组20例均选用20%-80%R-R间期组为全剂量扫描;比较两组病例的图像质量及辐射剂量。结果 A组平均辐射剂量(6.91±2.78),B组为(10.43±3.36),A组比B组减少了33.77%的辐射剂量;辐射剂量有统计学差异(P0.05),而图像质量无明显差别。结论在前瞻性序列扫描中运用ECG管电流调制技术可以明显降低大体重患者的辐射剂量。     

数字化断层融合技术在颌骨病变中的应用研究

目的：探讨数字化断层融合(TOMOS)技术在口腔有固定金属假牙的颌骨病变中的应用价值,并与多层螺旋CT (MSCT)进行对照。方法回顾分析口腔有固定金属假牙患者的TOMOS及MSCT的影像资料,每组各25例,观察曝光时间、患者受辐射剂量及对病灶的显示情况,并进行统计学分析。结果 TOMOS组的曝光时间为(0.700±0.050) s,明显少于CT组的(6.267±0.709) s,两组比较差异具有显著统计学意义(t=7.912,P<0.01);TOMOS组患者受辐射有效剂量为(0.033±0.004) mSv,明显低于CT组的(1.667±0.537) mSv,两组比较差异具有显著统计学意义(t=11.812,P<0.01);对下颌角及升支病变显示,TOMOS明显优于MSCT。结论 TOMOS检查方法实用、便捷,其辐射剂量不到CT的2%,在有金属假牙者的下颌角及升支病变的检查优势明显,可部分代替CT检查。     

多柔比星脂质体注射液与多柔比星注射液大鼠重复给药毒性的比较

目的研究大鼠连续静脉注射给予多柔比星脂质体注射液和多柔比星注射液后对大鼠产生的毒性作用及毒性异同比较。方法 SD大鼠90只,随机分为溶剂对照组、多柔比星脂质体注射液(1 mg/kg)和多柔比星注射液(1 mg/kg)组。各组大鼠每3 d静脉注射1次,连续给药13次,检测其体重、血液生化学、血液学、脏器系数等指标,并进行组织病理学检查。结果多柔比星脂质体注射液1 mg/kg可引起SD大鼠脱毛和溃疡,体重增长明显延缓,PLT、ALT、BUN升高,ALB降低,心脏和肾脏系数增大,胸腺和睾丸系数减小,组织病理学检查结果显示睾丸曲细精管生精上皮脱落,各级生精细胞消失,部分间质水肿;心脏心肌纤维断裂、溶解,横纹及部分细胞核消失;肾脏出现肾小管透明管型等病理组织学病变。与多柔比星脂质体注射液比较,相同剂量下多柔比星注射液亦可引起以上病变,但大鼠脱毛和皮肤溃疡率降低,肾脏毒性和心脏毒性明显增加。结论多柔比星脂质体注射液与普通注射液比较,心脏和肾脏毒性明显减轻,但皮肤毒性明显增加。     

Interaction between the biological effects of high- and low-LET radiation dose components in a mixed field exposure

Abstract

Purpose: The relative biological effectiveness of two epithermal neutron sources, a reactor based source at Studsvik, Sweden, and a proton accelerator-based source in Birmingham, UK, was studied in relation to the proportional absorbed dose distribution as a function of neutron energy. Evidence for any interactions between the effects of biological damage induced by high- and low-linear energy transfer (LET) dose components, in this ‘mixed field’ irradiation, was also examined

Materials and methods: Clonogenic survival in Chinese Hamster-derived V79 cells was used to assess biological effectiveness in this study. Cells were irradiated in suspension at 4°C at depths of 20, 35, 50 and 65 mm in a water phantom. This prevented the repair of sublethal damage, predominantly that produced by both incident and induced γ-rays in the field, over the variable periods of exposure required to irradiate cells with the same total absorbed dose. Cell survival, as a function of the absorbed radiation dose and depth in the phantom, was compared with Monte Carlo N-Particle (MCNP) calculations of the proportional absorbed dose distribution as a function of neutron energy for the two sources.

Results: In terms of the dose-related reduction in clonogenic cell survival, the epithermal neutron source at Studsvik was more biologically effective than the Birmingham source at all depths considered in the phantom. Although the contribution from the high-LET dose component was greater for the Studsvik source at 20 mm depth in the phantom, at greater depths the dose contribution from the high-LET dose component at Studsvik overlap with those for the Birmingham source. However, the most striking difference is in the fast neutron component to the dose of the two sources, neutron energies > 1 MeV were only associated with the Studsvik source. The relative biological effectiveness (RBE) of both sources declined slightly with depth in the phantom, as the total high-LET dose component declined. The maximum source RBE for Studsvik was 2.70 ± 0.50 at 20 mm; reduced to 2.10 ± 0.35 at depths of 50 and 65 mm. The corresponding values for Birmingham were 1.68 ± 0.25 and 1.31 ± 0.19, all values relate only to the surviving fraction of V79 cells at 37%, since RBE values are only applicable to the selected endpoint. Based on a dose reduction factor (DRF) of 1.0 for the total low-LET component to the absorbed dose, the RBE values for the high-LET dose component (fast neutrons and induced protons from the nitrogen capture reaction) was 14.5 and 7.05 for the Studsvik and Birmingham neutron sources, respectively. This is well outside the range of RBE historically reported values for V79 cells for the same level of cell survival for fast neutrons. The calculation of RBE values, based on the proportional absorbed dose distribution as a function of neutron energy, from historical data, and using a RBE of 1.8 for the dose from the nitrogen capture reaction, suggests RBE values for the total high-LET dose component of 3.1–2.8 and 2.5–2.0 for Studsvik and Birmingham, respectively, values again declining with depth in the phantom.

Conclusions: The overall biological effectiveness of the mixed field irradiation from an epithermal neutron sources depends on the composition and quality of the different dose components. The experimentally derived RBE values for the total high-LET dose components in these ‘mixed field’ irradiations are well in excess of historical data for fast neutrons. The difference between the historically expected and the observed RBE values is attributed to the interactions between the damage produced by high- and low-LET radiation.     

A role for p53 in the response of bystander cells to receipt of medium borne signals from irradiated cells

Abstract

Purpose: A number of contradictory studies have reported a role or not for p53 (protein 53) in the production of radiation-induced bystander effects. Most of these studies looked at a range of cell lines with normal or compromised p53 function.

Methods: In this study, Human Colon Tumour line 116 (HCT 116) cells with confirmed wild type p53 function and a corresponding p53 null HCT 116 line were used to test for bystander signal production and response to bystander signals in a mix/match protocol using the medium transfer technique.

Results: The results showed that both the null cells and the wild type cells produced bystander signals. However, only the p53 wild type cells responded to signals from either cell line. The Human Papilloma Virus transfected keratinocyte line G (HPV-G) reporter cell line used routinely in our laboratory was used to confirm that the null cells were producing signals.

Conclusions: We conclude that in this system the p53 pathway is involved in response of cells to bystander signals but that signals can be produced by cells which do not have functional p53. If these results apply in vivo, they could be important in radiotherapy where tumours may have compromised p53 function but surrounding (and distant) normal tissue may have wild type functional p53.     

Chronic exposure by ingestion of environmentally relevant doses of 226Ra leads to transient growth perturbations in fathead minnow (Pimephales promelas,Rafinesque, 1820)

Abstract

Purpose: To assess the impact of environmentally relevant levels of ingested ²²⁶Ra on a common freshwater fish species.

Methods: Fathead minnow (Pimephales promelas, Rafinesque) were obtained at the first feeding stage and established on a commercial fish food diet containing ²²⁶Ra in the activity range 10 mBq/g^?1, –10,000 mBq/g^?1. They remained on this diet for 24 months and were sampled invasively at 1,6,18 and 24 months to assess growth, biochemical indices and accumulated dose and non-invasively also at 12 and 15 months to assess growth.

Results: Fish fed 10 and 100 mBq/g^?1 diet showed a small transitory deregulation of growth at 6 and 12 months. Fish fed higher activities showed less significant or insignificant effects. There was a trend at 18 months which was stronger at 24 months for the population distribution to change in all of the ²²⁶Ra fed groups so that smaller fish were smaller and bigger fish were bigger than the controls. There were also significant differences in the ratios of protein:DNA at 24 months which were seen as a trend but were not significant at earlier time points.

Conclusions: Fish fed a radium diet for 2 years show a small and transitory growth dysregulation at 6 and 12 months. The effects predominate at the lower activities suggesting hormetic or homeostatic adjustments. There was no effect on growth of exposure to the high activities ²²⁶Ra. This suggests that radium does not have a serious impact on the ecology of the system and the level of radium that would be transferred to humans is very low. The results may be important in the assessment of long-term environmental impacts of ²²⁶Ra exposure.     

Estimation of annual effective dose due to ingestion of natural radionuclides in foodstuffs and water at a proposed uranium mining site in India

Abstract

Purpose: To study the distribution of ²¹⁰Po, ²²⁶Ra, ²³⁰Th and U(nat) (naturally occurring radioisotopes of uranium [²³⁴U, ²³⁵U and ²³⁸U]) in food and water around the Bagjata uranium mining area in India.

Materials and methods: Radionuclides were analyzed in food samples of plant and animal origin after acid digestion. Intake and ingestion dose of the radionuclides were estimated.

Results: ²¹⁰Po, ²²⁶Ra, ²³⁰Th and U(nat) in all the dietary components ranged widely from < 0.2–36, < 0.02–1.58, < 0.01–2.8 and < 0.017–0.39 Bqkg^-1, respectively. The range of ²²⁶Ra and U(nat) in water was < 3.5–206 and < 12.6–693 mBql^?1, respectively. The intake of radionuclides considering food and water was calculated to be 760 BqY^?1 while the ingestion dose was 601 μSvY^?1. The estimated doses reflect the natural background dose via route of ingestion, which is below the 1 mSvY^?1 limit set by the International Commission on Radiological Protection (ICRP). However, the doses are more than the dose constraint of 300 μSvY^?1 as suggested by the ICRP for members of the public for planned disposal of long-lived radioactive waste.

Conclusion: The study confirms that current levels of radionuclides do not pose significant radiological risk to the local inhabitants, but they need close investigation in the near future.