Changing radiation dose from diagnostic computed tomography examinations in Saskatchewan

Purpose

Follow-up study to observe if provincial mean effective radiation dose for head, chest, and abdomen-pelvis (AP) computed tomographies (CTs) remained stable or changed since the initial 2006 survey.

Methods

Data were collected in July 2008 from Saskatchewan's 13 diagnostic CT scanners of 3358 CT examinations. These data included the number of scan phases and projected dose length product (DLP). Technologists compared projected DLP with 2006 reference data before scanning. Projected DLP was converted to effective dose (ED) for each head, chest, and AP CT. The total dose that the patients received with scans of multiple body parts at the same visit also was determined.

Results

The mean (± SD) provincial ED was 3.4 ± 1.6 mSv for 1023 head scans (2.7 ± 1.6 mSv in 2006), 9.6 ± 4.8 mSv for 588 chest scans (11.3 ± 8.9 mSv in 2006), and 16.1 ± 9.9 mSv for 983 AP scans (15.5 ± 10.0 mSv in 2006). Single-phase multidetector row CT ED decreased by 31% for chest scans (9.5 ± 3.9 mSv vs 13.7 ± 9.7 mSv in 2006) and 17% for AP scans (13.9 ± 6.0 mSv vs 16.8 ± 10.6 mSv in 2006) and increased by 19% for head scans (3.2 ± 1.2 mSv vs 2.7 ± 1.5 mSv in 2006). The total patient dose was highest (33.8 ± 10.1 mSv) for the 20 patients who received head, neck, chest, and AP scans during a single visit. Because of increased utilisation and the increased CT head dose, Saskatchewan per capital radiation dose from CT increased by 21% between 2006 and 2008 (1.14 vs 1.38 mSv/person per year).

Conclusion

Significant dose and variation reduction was seen for single-phase CT chest and AP examinations between 2006 and 2008, whereas CT head dose increased over the same interval. These changes, combined with increased utilisation, resulted in per capita increase in radiation dose from CT between the 2 studies.     

2014年浙江省台州市适龄儿童扩大国家免疫规划疫苗接种率横断面调查

目的 了解浙江省台州市适龄儿童扩大国家免疫规划(national immunization program, NIP)疫苗接种现状。方法 采用分层整群随机抽样方法,对台州市所辖9个县(市、区)随机抽取45个乡镇、90个村和9个流动人口聚集地,采用入户见人查证方法进行疫苗接种情况调查。结果 本次共调查2202名儿童,其中本地儿童1922名,流动儿童280名。本地儿童22剂次NIP疫苗接种率,除A群C群脑膜炎球菌多糖疫苗(MPV-A+C2)外,其余疫苗接种率均95%,含麻类疫苗首针(MCV1)及时接种率89.64%,乙型病毒性肝炎(乙肝)疫苗首针(HepB1)及时接种率98.60%、五苗全程(BCG、OPV1-3、DTP1-3、 HepB1-3、MCV1)接种率96.63%。除(MPV-A+C1)、(MPV-A+C2)和 OPV4外,本地儿童加强免疫疫苗接种率各年龄组之间差异有统计学意义(P0.001);流动儿童除口服脊髓灰质炎减毒活疫苗(OPV)第4剂(OPV4)90.28%、A群C群脑膜炎球菌多糖疫苗第1剂(MPV-A+C1)89.44%、A群C群脑膜炎球菌多糖疫苗第2剂(MPV-A+C2)90.00%、甲型病毒性肝炎疫苗(HepA)91.89%、白破(DT)疫苗94.12%外,22剂次NIP疫苗其余剂次接种率均95%;含麻类疫苗首针(MCV1)及时接种率84.46%、乙肝疫苗首针(HepB1)及时接种率91.79%、五苗全程(BCG、OPV1-3、DTP1-3、 HepB1-3、MCV1)接种率94.64%。流动儿童各年龄组加强免疫疫苗接种率差异无统计学意义(P0.05)。结论 台州本地儿童和流动儿童NIP疫苗接种率均处于较高水平,且A群C群脑膜炎球菌多糖疫苗和白破疫苗接种率较2013年明显提高。     

CT CARE kV低管电压扫描联合CPR技术术前评估面神经管骨折

目的 探讨智能最佳管电压(CARE kV)低剂量CT扫描及CPR技术在术前评估面神经管骨折中的价值。方法 收集头部外伤伴单侧面瘫患者,采用CARE kV技术进行颞骨HRCT扫描,按就诊先后分4组:A组108例(CARE kV On),管电压120 kVp,B~D组分别为114、105、109例(CARE kV Semi),管电压分别为120 kVp、100 kVp、80 kVp;观察CPR图像面神经管,比较4组患者面神经管骨折发生率、发生部位并与手术结果对照;比较4组间图像质量客观评价指标,包括CT值、噪声(SD)、SNR、CNR及辐射剂量参数[容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效剂量(ED)]。结果 共纳入436例患者,面神经管骨折174例(174/436,39.91%)。A~D组骨折发生率分别为43.52%(47/108)、39.47%(45/114)、37.14%(39/105)、39.45%(43/109);术前HRCT诊断面神经管骨折与手术结果具有较好的一致性(Kappa>0.5);膝状窝骨折发生率最高(100/174,57.47%),迷路段最低(5/174,2.87%)。A~D组SD、SNR、CNR差异有统计学意义(P<0.05),两两比较除A、B组外余各组间比较差异均有统计学意义(P均<0.05);A~D组CTDIvol、DLP、ED、有效电流差异有统计学意义(P<0.05),经两两比较除A、B组外余各组间比较差异均有统计学意义(P均<0.05)。结论 CARE kV联合CPR术前能够准确评估面神经管骨折情况,并可在满足诊断的前提下降低辐射剂量。     

低电压自动管电流调节技术在上腹部增强CT扫描中的应用

目的 探讨低电压自动管电流调节(ATCM)技术在上腹部增强CT扫描中的价值。方法 将腹围<90 cm的100例患者随机分为2组,观察组(n=50):管电压100 kV,ATCM,动、静脉期参考管电流250、230 mAs。对照组:管电压120 kV,ATCM,动、静脉期参考管电流为210、190 mAs。测量并对比两组图像噪声、肝脏和胰腺SNR、肝脏-竖脊肌和胰腺-竖脊肌CNR、腹主动脉CT值、腹主动脉SNR、腹主动脉-竖脊肌CNR、静脉期容积CT剂量指数(CTDlvol)、剂量长度乘积(DLP)及有效剂量(ED)。结果 两组图像噪声、肝脏SNR、胰腺SNR、腹主动脉CT值、CTDIvol、DLP、ED比较,差异均有统计学意义(P均<0.05);腹主动脉SNR、腹主动脉-竖脊肌CNR、肝脏-竖脊肌CNR、胰腺-竖脊肌CNR、腹腔干三维分支评分及血管清晰度评分、轴位图像主观评价比较,差异均无统计学意义(P均>0.05)。结论 低管电压、ATCM上腹部增强CT扫描可降低辐射剂量,提高动脉血管显影程度,可满足诊断要求。     

千伏级锥形束CT计算宫颈癌放疗剂量

目的 探讨宫颈癌放疗中采用加速器机载千伏级锥形束CT(kV-CBCT)影像进行剂量计算的准确性和可行性。方法 分别于CT模拟机和kV-CBCT上扫描CIRS-062电子密度模体,获得电子密度模体影像及计划CT(pCT)和kV-CBCT的CT值-相对电子密度曲线,采用治疗计划系统计算剂量。选取9例宫颈癌患者的调强治疗计划,并将计划移植至模体和患者的pCT和kV-CBCT影像进行剂量计算,比较剂量差异及剂量分布情况。结果 kV-CBCT的CT值经多次重复测量最大变化≤3%;kV-CBCT的CT值-相对电子密度曲线与pCT相比,低密度组织的差异较小,高密度者差异相对较大。在对模体的剂量计算中,pCT和kV-CBCT的剂量差异为0.7%~2.5%,平均(1.23±0.55)%;而在对宫颈癌患者的剂量计算中,剂量差异为0.5%~1.8%,平均(0.84±0.44)%;剂量分布的一致性均较好。结论 宫颈癌放疗中采用kV-CBCT影像进行剂量计算是可行的。     

Flash双源CT智能最佳管电压技术在小儿中耳胆脂瘤面神经管裸露中的应用

目的 评价高分辨率CT(HRCT)智能最佳管电压技术(CARE kV技术)在中耳炎患儿颞骨检查中对降低辐射剂量和显示面神经管裸露的应用价值。方法 收集中耳炎患儿(2~4岁)176例;按就诊先后顺序分为A组88例,采用CARE kV技术行颞骨HRCT扫描,B组88例,常规颞骨HRCT扫描。比较两组中耳胆脂瘤、面神经管裸露、HRCT图像质量及辐射剂量情况,并进行统计学分析。结果 A、B两组中耳胆脂瘤发生率[59.09%(52/88)vs 64.77%(57/88)]差异无统计学意义(χ²=0.020,P=0.887)。术前HRCT诊断中耳胆脂瘤的准确率两组间差异无统计学意义[96.15%(50/52) vs 96.49%(55/57),χ²=0.199,P=0.639]。A、B两组术前HRCT诊断面神经管裸露发生率分别为29.54%(26/88)和31.82%(28/88),术中观察面神经管裸露发生率分别为27.27%(24/88)和28.41%(25/88),两组间术前HRCT诊断及术中观察面神经管裸露发生率差异均无统计学意义(χ²=0.978、χ²=0.440,P均>0.05)。鼓室段面神经管裸露发生率最高(25/49,51.02%),迷路段最低(5/49,10.20%)。两组中,前膝段面神经管裸露长度术前HRCT与术中测量值差异有统计学意义(P均<0.05),其余各段差异均无统计学意义(P均>0.05)。两组间CT平均值、噪声(SD)、SNR、CNR差异无统计学意义(P均>0.05)。两组间剂量长度乘积(DLP)、有效剂量(ED)差异均有统计学意义(P=0.039、0.028)。结论 小儿颞骨HRCT智能最佳管电压技术能准确诊断面神经裸露,同时保证图像质量并有效降低辐射剂量。     

BOLD-fMRI用于邻近大脑初级运动皮层脑胶质瘤术后调强放疗的可行性

目的初步探讨BOLD-fMRI指导邻近大脑初级运动皮层(PMC)脑胶质瘤术后调强放疗(IMRT)的可行性。方法收集30例邻近PMC脑胶质瘤术后拟行放疗患者,行常规MR平扫+增强及BOLD-fMRI检查。获取PMC相关数据并与相应的MRI、CT图像融合,导入放疗计划系统并依此勾画靶区、危及器官及PMC,采用IMRT技术分别制定考虑(IMRT-PMC)与不考虑PMC(IMRT-noPMC)剂量保护的两种放疗计划并进行比较。结果IMRT-PMC与IMRTnoPMC相比较,计划靶区(PTV)的所受最大辐射剂量(Dmax)、平均辐射剂量(Dmean)及适形指数(CI)、剂量均匀性指数(HI)差异均无统计学意义(P均>0.05),常规危及器官的Dmax及Dmean差异均无统计学意义(P均>0.05)。IMRT-PMC计划中患侧、健侧PMC的Dmax及Dmean均明显低于IMRT-noPMC计划(P均<0.05)。结论 BOLD-fMRI能够明确PMC的位置及与脑胶质瘤术后放疗靶区的关系,有助于制定保护性放疗方案,最大程度减低PMC所受辐射剂量,从而降低放疗后发生放射性损伤的可能。     

Provider’s and User’s Perspective about Immunization Coverage among Migratory and Non-migratory Population in Slums and Construction Sites of Chandigarh

Strengthening routine immunization is a corner stone for countries to achieve the United Nations Millennium Development Goal 4 (MDG 4) which aims to reduce under-five mortality by two-thirds and MDG 5 improving maternal health compared to 1990 estimates by 2015. The poor urban newborns are more vulnerable to many health and nutrition problems compared to the non-poor urban counterparts. Therefore there is a need to strengthen health system to cater the needs of urban poor. Standardized WHO30*7 cluster sampling for slums and convenience sampling for construction sites. In depth interviews were conducted for user’s as well as provider’s perspective about immunization coverage. Two hundred ten children and 210 mothers were enrolled in slums and 100 were sampled from construction sites. The slum workers are considered as non-migratory groups whereas construction site workers are considered as migratory population. Among children, 23 % were fully immunized, 73 % were partially immunized and 3 % were unimmunized in non-migratory population whereas 3 % were fully immunized, 91 % were partially immunized and 6 % were unimmunized in migratory population. Among mothers, 43 and 39 % were fully immunized, 13 and 15 % partially immunized and 43 and 46 % were unimmunized in non-migratory and migratory population, respectively. The various reasons attributed for low coverage are (a) dissatisfaction of the users with the service delivery and procedural delays (bureaucracy), (b) lack of faith in health workers, (c) insistence upon ID/vaccination card/aadhar card by the health worker before vaccinating child and (d) ignorance of the need of immunization by the people and migration of the population.     

低辐射剂量在超重和肥胖人群冠状动脉 CTA 中的应用研究

目的：初步探讨通过降低kV降低超重和肥胖人群冠状动脉CTA辐射剂量的可行性。方法连续收集超重患者60例、肥胖患者72例,每组均分成低剂量组和常规剂量组,分别记作A1和A2、B1和B2组, A1组采用100 kV、A2和B1组120 kV、B2组采用140 kV,对比剂选用碘海醇（350 mg／ml）进行增扫描。对冠状动脉9个主要节段图像进行主观评分,对右冠状动脉近段（RCA-p）、左主干LM（LMA）、左前降支近段（LAD-p）、左回旋支近段（LCX-p）4个主要节段管腔增强后CT值及SD和同水平前胸壁肌肉组织的CT值及SD进行记录。对A1和A2、B1和B2以上增强水平、图像评分、图像噪声、信噪比（ SNR）、噪声比（ CNR）、有效辐射剂量（ ED）等进行分析比较。结果所有纳入病例均完成冠脉检查,图像质量满足诊断要求。9个冠脉节段图像评分、4个冠脉节段增强水平、图像噪声、SNR差异无明显统计学意义, CNR、ED差异具有统计学意义。 A1组和A2组ED 分别为（8ó．47±0．76） mSv和（12．22±2．41）mSv,B1和B2组ED分别为（13．69±1．142）mSv和（20．31±1．36） mSv。结论对于超重和肥胖人群进行冠脉检查,可通过降低kV减少检查个体的有效辐射剂量,降低冠脉图像CNR。