Chaudhry Rajeev, Dangle Pankaj P, Cannon Glenn M, Schneck Francis X, Stephany Heidi A
Department of Urology, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.
Department of Urology, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA; Department of Urology, University of Alabama School of Medicine, 1600 7th Ave South, Suite 318 Lowder Bldg., Birmingham, AL, 35233, USA.
J Pediatr Urol. 2021 Dec;17(6):790.e1-790.e5. doi: 10.1016/j.jpurol.2021.09.010. Epub 2021 Sep 14.
Skin entrance doses for voiding cystourethrogram (VCUG) have not been well characterized in the literature. Radiation exposure is measured as either dose area product (DAP) or air kerma, which estimates the effective dose, but does not accurately reflect absorbed dose at skin level.
The objective of this study was to measure the skin entrance dose during fluoroscopic VCUG study in pediatric patients using single point dosimeters.
Pediatric patients undergoing fluoroscopic VCUG were prospectively enrolled in our study. Landauer NanoDot™OSLD dosimeters were affixed to the skin overlying the sacrum to measure skin entrance dose. The fluoroscopic unit was set to the following parameters: low dose setting, skin-to-source distance of 54 cm, pulsed fluoroscopy at 3 frames/sec.
Forty-four patients with a median age of 13.6 months (IQR 3.7-42.3) were enrolled. Median fluoroscopic time was 54 s (IQR 36-72). The median values absorbed dose by dosimeter and air kerma were 0.32 mGy (IQR 0.13-0.56, range 0.01-2.9) and 0.24 mGy (IQR 0.14-0.37), respectively. There was a positive correlation between the air kerma and absorbed dose (r = 0.69, p < 0.001) and fluoroscopy time and absorbed dose mGy (r = 0.60, p < 0.001). Absorbed dose was independent of age, body mass index and body surface area (p = 0.19, p = 0.57 and p = 0.16, respectively). Median whole body effective dose was 0.04 mSv (IQR 0.02-0.7).
Overall, the absorbed dose received by the dosimeter remained low at a median of 0.32 mGy (range 0.01-2.91). These values are remarkably low and well within the accepted radiation exposure norms. Our radiologists follow a strict protocol to reduce the overall radiation emitted during a VCUG. These measures include setting the x-ray source at a low dose mode, collimating to the smallest area possible, and using pulsed fluoroscopy at 3 frames/sec. Limitations to this study include a slight variability in technique of VCUG between different technicians and providers, for which we cannot control.
The radiation dose absorbed at the skin entrance and uniform whole body effective dose is low for a single VCUG when utilizing strict parameters. While newer non-ionizing technologies continue to emerge, our data is encouraging and will serve as a valuable tool when educating parents regarding radiation doses associated with a VCUG.
排尿性膀胱尿道造影（VCUG）的皮肤入射剂量在文献中尚未得到充分描述。辐射暴露通过剂量面积乘积（DAP）或空气比释动能来测量，后者可估算有效剂量，但不能准确反映皮肤层面的吸收剂量。
本研究的目的是使用单点剂量仪测量儿科患者在荧光透视VCUG检查期间的皮肤入射剂量。
前瞻性纳入接受荧光透视VCUG检查的儿科患者。将Landauer NanoDot™OSLD剂量仪贴于骶骨上方的皮肤，以测量皮肤入射剂量。荧光透视设备设置为以下参数：低剂量设置、皮肤至源距离54厘米、每秒3帧的脉冲荧光透视。
纳入44例患者，中位年龄13.6个月（四分位间距3.7 - 42.3）。中位荧光透视时间为54秒（四分位间距36 - 72）。剂量仪吸收剂量和空气比释动能的中位值分别为0.32毫戈瑞（四分位间距0.13 - 0.56，范围0.01 - 2.9）和0.24毫戈瑞（四分位间距0.14 - 0.37）。空气比释动能与吸收剂量之间存在正相关（r = 0.69，p < 0.001），荧光透视时间与吸收剂量毫戈瑞之间也存在正相关（r = 0.60，p < 0.001）。吸收剂量与年龄、体重指数和体表面积无关（p分别为0.19、0.57和0.16）。中位全身有效剂量为0.04毫希沃特（四分位间距0.02 - 0.7）。
总体而言，剂量仪接收的吸收剂量中位数为0.32毫戈瑞（范围0.01 - 2.91），仍处于较低水平。这些值非常低，完全在可接受的辐射暴露规范范围内。我们的放射科医生遵循严格方案以减少VCUG期间发出的总体辐射。这些措施包括将X射线源设置为低剂量模式、尽可能准直至最小面积以及使用每秒3帧的脉冲荧光透视。本研究的局限性包括不同技术人员和提供者之间VCUG技术存在轻微差异，对此我们无法控制。
在采用严格参数时，单次VCUG的皮肤入射吸收剂量和全身均匀有效剂量较低。虽然更新的非电离技术不断涌现，但我们的数据令人鼓舞，在向家长介绍与VCUG相关的辐射剂量时将成为有价值的工具。
