**5. CT fluoroscopy (CTF)**

The substantial advances in CT technology have led to development in CT fluoroscopy in 1993, which allows fluoroscopic image acquisition with high image quality compared to conventional fluoroscopy [7]. This development in CT technology (slip ring technology in 1980s and X-ray tubes with high anode heat storage capacity up to 30 million heat units (MHU) or 22,000 kJ) and high speed processing units and advances in reconstruction software, enabled acquisition of high image quality in a short time with lower radiation dose) [8]. CT fluoroscopy becomes popular in image-guided intervention despite of the concern regarding radiation risks due to its advantages compared with conventional fluoroscopy and surgery. CT fluoroscopy is very valuable biopsy for deep structures, stent placement, and lesion drainage. CT fluoroscopy is usually performed using the following exposure parameters: 120 kVp, 30–90 mA, scan time range from 0.5 to 1.0 s, and fluoroscopic images displayed in certain time interval range between 3 s−<sup>1</sup> and `12 s−<sup>1</sup> [9].

**6.2. Tissue reaction in image-guided intervention**

\*actual skin dose not entrance surface air kerma

1.5 Nausea, diarrhea

3.0 50% chance of death

**Table 2.** Biological effects of radiation [11, 12].

6.0 Death

**Radiation equivalent** 

**dose (Sv)**

**Table 1.** Tissue reaction effects of acute radiation exposure.

**Subsequent effect**

The dose rate during fluoroscopic-guided intervention ranged between 0.02 and 0.05 Gy/minute [10]. It was estimated that the mean patient dose for cardiac catheterization is 2.5 Gy, and during percutaneous interventions, the dose may reach 6.4Gy per procedures, which is higher than the erythema dose [11]. Erythema occurs due to accumulative patient doses from multiple procedures, each of which is individually insufficient to cause injury. Most of the patients require more than one procedure within a short time such as patients with ischemic heart diseases (IHD). **Table 1** shows the tissue reaction threshold during image-guided intervention procedures using fluoroscopy. **Table 2** illustrates the biological effect on patients after exposure to certain doses.

Medical Imaging and Image-Guided Interventions http://dx.doi.org/10.5772/intechopen.76608 41

**Figures 6**–**11** show radiation-induced skin injuries due to prolonged irradiation.

**Deterministic effect Typical threshold dose (Gy)\* Time of onset\*** Early transient erythema 2 ~2–24 hours Temporary epilation 3 ~3 weeks Main erythema 6 ~10 days Permanent epilation 7 ~3 weeks Invasive fibrosis 10 — Dry desquamation 14 ~4 weeks Late erythema 15 ~8–10 weeks Moist desquamation 18 ~4 weeks Ischemic dermal necrosis 18 >10 weeks Secondary ulceration 24 > 6 weeks Dermal atrophy (1st phase) 10 >52 weeks Telangiectasia 10 > 52 weeks Dermal necrosis (delayed) >12 >52 weeks

0.25 Blood changes (e.g., measurable hematologic depression, decrease in the number of

lymphocytes present in the circulating blood)

2.0 Erythema (diffuse redness over an area of skin after irradiation)

2.5 If dose is administered to gonads, temporary sterility
