Korean J Radiol.  2019 Jan;20(1):166-170. 10.3348/kjr.2017.0772.

Technical Report: A Cost-Effective, Easily Available Tofu Model for Training Residents in Ultrasound-Guided Fine Needle Thyroid Nodule Targeting Punctures

  • 1Department of Ultrasound, The First Hospital of China Medical University, Shenyang, China. wxmcmu@163.com
  • 2Department of Transplantation and General Surgery, The First Hospital of China Medical University, Shenyang, China.


To establish a cost-effective and easily available phantom for training residents in ultrasound-guided fine needle thyroid nodule targeting punctures.
Tofu, drinking straws filled with coupling gel, a urine tube, and 21-gauge needles were used to generate a phantom thyroid with nodules for training. Twelve radiology residents were involved in the study. The puncture success rates were recorded and compared before and after phantom training using the Wilcoxon signed-rank test.
On ultrasonography, tofu mimicked the texture of the thyroid. Drinking straws filled with coupling gel mimicked vessels. The urine tube filled with air mimicked the trachea, and 21-gauge needles mimicked small nodules in the transverse section. The entire phantom was similar to the structure of the thyroid and surrounding tissues. The puncture success rates of radiology residents were significantly increased from 34.4 ± 14.2% to 66.7 ± 19.5% after training (p = 0.003). The phantom was constructed in approximately 10 minutes and materials cost less than CNY 10 (approximately $ 1.5) at a local store.
The tofu model was cost-effective, easily attainable, and effective for training residents in ultrasound-guided fine needle thyroid nodule targeting punctures in vitro.


Ultrasound-guided; Fine needle aspiration biopsy; Thyroid nodules; Phantoms

MeSH Terms

In Vitro Techniques
Soy Foods*
Thyroid Gland*
Thyroid Nodule*


  • Fig. 1 Preparation of thyroid phantom for fine needle puncture. 1, Tofu; 2, drinking straw; 3, urine tube; 4, 21-gauge needle; 5, 25-gauge puncture needle.

  • Fig. 2 Thyroid phantom. 1, Tofu; 2, drinking straw; 3, urine tube; 4, 21-gauge needle; 5, 25-gauge puncture needle; 6, probe.

  • Fig. 3 Designated inserting trace. Arrows, designated inserting traces; dark spots, transverse section of 21-gauge needles mimicking “small nodules”; hollow circle 2, drinking straws mimicking “vessels”; hollow circle 3, urine tube mimicking “trachea.” Dark spots in a, b, e, and f represent superficial targets. Dark spots in c, d, g, and h represent deep targets. Residents were instructed to puncture b, c, f, and g with right-handed needling and a, d, e, and h with left-handed needling.

  • Fig. 4 Ultrasonography of phantom. 1, “thyroid” (tofu); 2, “vessel” (drinking straw); 3, “trachea” (urine tube); 4, “small nodule” (transverse section of 21-gauge needle); 5, 25-gauge needle.

  • Fig. 5 Comparison of success rates between pre- and post-training, superficial and deep targets, and right-handed and left-handed needling. A1, pre-training group; A2, post-training group; B1, superficial target group; B2, deep target group; C1, right-handed needling group; C2, left-handed needling group. Each circle, square, triangle, or rhombus represents success rate of resident in corresponding group. Middle transverse line of symbol “王” represents mean value of success rate in group. Upper and lower lines represent 95% confidence intervals. *Wilcoxon signed-rank test, p < 0.05.


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