Unusual arteries were usually thinner and more complicated, so it was particularly difficult to superselect the designated artery on the first attempt.
Arteries such as the hepatic, uterine and renal arteries were considered straight highways compared to the next artery Zheng Ren was going to superselect.
The radiculomedullary artery had a very complicated network. Zheng Ren carefully worked out the dosage of the contrast medium and parsimoniously made every injection after precise analysis and calculation.
He was worried about excessive contrast medium administration, which could force the end of the surgery.
Prolonged radiation exposure, which was constantly on Old Chief Physician Pan's mind, did not concern him in the slightest.
