After local anesthesia on right wrist area with lidocaine hydrochloride using a 26 gauge needle, the puncture is performed using a 20 gauge needle with the through-and-through puncture technique or a 21 gauge open needle with anterior wall puncture technique. After the successful puncture, 0.025-inch straight wire or 0.018-inch hair wire are inserted, followed by insertion of the 5Fr. radial sheath (Prelude® Radial; Merit medical, UT, USA or Radifocus® Introducer II or Glidesheath Slender®; Terumo Corporation, Tokyo, Japan).

After local anesthesia on left anatomical snuffbox area with lidocaine hydrochloride using a 26 gauge needle, the puncture is performed using a 20 gauge needle with the through-and-through puncture technique or a 21 gauge open needle with anterior wall puncture technique. After the successful puncture, 0.025-inch straight wire or 0.018-inch hair wire are inserted, followed by insertion of the 5Fr. radial sheath (Prelude® Radial; Merit medical, UT, USA or Radifocus® Introducer II or Glidesheath Slender®; Terumo Corporation, Tokyo, Japan).

We will perform coronary angiography through a Judkins 5 French diagnostic catheter and will take a basic view. At the end of the examination, the radial sheath is removed and the right conventional radial approach is performed for about 4 hours and the left snuffbox approach for about 2 hours using the compressive bandage method. The hemostatic device will use ez ClotRadial® (SOYEON medical Co., Ltd., Wonju, Korea).

Radiation dose (µSv) of the operator's head, hand, and body will be compared between right conventional radial artery approach and left snuffbox approach group.

Fluoroscopy time (second) will be compared between two groups during coronary angiography.