Masayuki Zuguchi

Relationship Between Fluoroscopic Time, Dose–Area Product, Body Weight, and Maximum Radiation Skin Dose in Cardiac Interventional Procedures

OBJECTIVE Real-time maximum dose monitoring of the skin is unavailable on many of the X-ray machines that are used for cardiac intervention procedures. Therefore, some reports have recommended that physicians record the fluoroscopic time for patients undergoing fluoroscopically guided intervention procedures. However, the relationship between the fluoroscopic time and the maximum radiation skin dose is not clear. This article describes the correlation between the maximum radiation skin dose and fluoroscopic time for patients undergoing cardiac intervention procedures. In addition, we examined whether the correlations between maximum radiation skin dose and body weight, fluoroscopic time, and dose-area product (DAP) were useful for estimating the maximum skin dose during cardiac intervention procedures. MATERIALS AND METHODS Two hundred consecutive cardiac intervention procedures were studied: 172 percutaneous coronary interventions and 28 cardiac radiofrequency catheter ablation (RFCA) procedures. The patient skin dose and DAP were measured using Caregraph with skin-dose-mapping software. RESULTS For the RFCA procedures, we found a good correlation between the maximum radiation skin dose and fluoroscopic time (r = 0.801, p < 0.0001), whereas we found a poor correlation between the maximum radiation skin dose and fluoroscopic time for the percutaneous coronary intervention procedures (r = 0.628, p < 0.0001). There was a strong correlation between the maximum radiation skin dose and DAP in RFCA procedures (r = 0.942, p < 0.0001). There was also a significant correlation between the maximum radiation skin dose and DAP (r = 0.724, p < 0.0001) and weight-fluoroscopic time product (WFP) (r = 0.709, p < 0.0001) in percutaneous coronary intervention procedures. CONCLUSION The correlation between the maximum radiation skin dose with DAP is more striking than that with fluoroscopic time in both RFCA and percutaneous coronary intervention procedures. We recommend that physicians record the DAP when it can be monitored and that physicians record the fluoroscopic time when DAP cannot be monitored for estimating the maximum patient skin dose in RFCA procedures. For estimating the maximum patient skin dose in percutaneous coronary intervention procedures, we also recommend that physicians record DAP when it can be monitored and that physicians record WFP when DAP cannot be monitored.

Radiation dose to the pediatric cardiac catheterization and intervention patient.

OBJECTIVE The radiation dose from cardiac catheterization is particularly relevant when treating children because of their greater radiosensitivity compared with adults. Moreover, cardiac catheterization is being used increasingly for interventional radiology procedures, possibly resulting in higher patient radiation doses. This article reports the radiation doses and related factors, such as fluoroscopy time, for children who underwent cardiac catheterization and children who underwent other interventional radiology procedures. MATERIALS AND METHODS We evaluated 239 consecutive patients who underwent cardiac catheterization (n = 205) or another interventional radiology procedure (n = 34) for which the dose-area product (DAP) was measured. The number of cine runs and fluoroscopic time for each procedure and the body mass index and body weight of each patient were recorded. We also used the double product combined with body weight, which is the weight- fluoroscopic time product. RESULTS The average DAP ± SD of cardiac catheterization and of an interventional radiology procedure was 1,702.6 ± 2,110.1 cGy × cm² and 2,242.2 ± 2,509.4 cGy × cm², respectively. The average fluoroscopic time ± SD of cardiac catheterization and of an interventional radiology procedure was 24.1 ± 16.8 minutes and 37.2 ± 20.0 minutes. For children who underwent cardiac catheterization and those who underwent an interventional radiology procedure, a strong correlation was seen between the DAP and weight-fluoroscopic time product (cardiac catheterization, r = 0.906; interventional radiology procedure, r = 0.885) and a good correlation was detected between the DAP and weight (r = 0.819 and 0.895, respectively). CONCLUSION There was a good correlation between the DAP and weight and between DAP and weight-fluoroscopic time product for children who underwent cardiac catheterization or an interventional radiology procedure. Therefore, body weight is important for determining radiation dose to children undergoing cardiac catheterization or an interventional radiology procedure. The normalized DAP (i.e., DAP divided by body weight), fluoroscopy time, and number of cine runs were greater in children who underwent an interventional radiology procedure than in those who underwent cardiac catheterization. Therefore, the radiation dose to children from interventional radiology procedures is a more critical issue.

Radiation Dose of Interventional Radiology System Using a Flat-Panel Detector

OBJECTIVE Currently, cardiac interventional radiology equipment has tended toward using flat-panel detectors (FPDs) instead of image intensifiers (IIs) because FPDs offer better imaging performance. However, the radiation dose from an FPD in cardiac interventional radiology is not clear. The purpose of our study was to measure the radiation doses during cineangiography and fluoroscopy of many cardiac radiology systems that use FPDs or IIs, in clinical settings. MATERIALS AND METHODS This study examined 20 radiology systems in 15 cardiac catheterization laboratories (11 used FPD and nine used II). The entrance surface doses with digital cineangiography and fluoroscopy were compared for the 20 systems using acrylic plates (20-cm thick) and a skin dose monitor. RESULTS For fluoroscopy, the average entrance surface doses of the 20-cm-thick acrylic plates were identical for FPD (average +/- SD, 16.63 +/- 7.89 mGy/min; range, 5.7-26.4 mGy/min; maximum/minimum, 4.63) and II (17.81 +/- 12.52 mGy/min; range, 6.5-42.2 mGy/min; maximum/minimum, 6.49) (p = 0.799). For digital cineangiography, the average entrance surface dose of the 20-cm-thick acrylic plate was slightly lower with FPD (29.68 +/- 16.40 mGy/10 s; range, 8.9-58.5 mGy/10 s; maximum/minimum, 6.57) than with II (38.50 +/- 33.71 mGy/10 s; range, 15.2-117.1 mGy/10 s; maximum/minimum, 7.70), although the difference was not significant (p = 0.487). CONCLUSION We found that the average entrance doses of cineangiography and fluoroscopy in FPD systems were not significantly different from those in II systems. Hence, FPDs did not inherently reduce the radiation dose, although FPDs possess good detective quantum efficiency. Therefore, to reduce the radiation dose of cardiac interventional radiology systems, even FPD systems, practical measures are necessary.

Occupational Dose in Interventional Radiology Procedures

OBJECTIVE Interventional radiology tends to involve long procedures (i.e., long fluoroscopic times). Therefore, radiation protection for interventional radiology staff is an important issue. This study describes the occupational radiation dose for interventional radiology staff, especially nurses, to clarify the present annual dose level for interventional radiology nurses. MATERIALS AND METHODS We compared the annual occupational dose (effective dose and dose equivalent) among interventional radiology staff in a hospital where 6606 catheterization procedures are performed annually. The annual occupational doses of 18 physicians, seven nurses, and eight radiologic technologists were recorded using two monitoring badges, one worn over and one under their lead aprons. RESULTS The annual mean ± SD effective dose (range) to the physicians, nurses, and radiologic technologists using two badges was 3.00 ± 1.50 (0.84-6.17), 1.34 ± 0.55 (0.70-2.20), and 0.60 ± 0.48 (0.02-1.43) mSv/y, respectively. Similarly, the annual mean ± SD dose equivalent range was 19.84 ± 12.45 (7.0-48.5), 4.73 ± 0.72 (3.9-6.2), and 1.30 ± 1.00 (0.2-2.7) mSv/y, respectively. The mean ± SD effective dose for the physicians was 1.02 ± 0.74 and 3.00 ± 1.50 mSv/y for the one- and two-badge methods, respectively (p < 0.001). Similarly, the mean ± SD effective dose for the nurses (p = 0.186) and radiologic technologists (p = 0.726) tended to be lower using the one-badge method. CONCLUSION The annual occupational dose for interventional radiology staff was in the order physicians > nurses > radiologic technologists. The occupational dose determined using one badge under the apron was far lower than the dose obtained with two badges in both physicians and nonphysicians. To evaluate the occupational dose correctly, we recommend use of two monitoring badges to evaluate interventional radiology nurses as well as physicians.

Total Entrance Skin Dose: An Effective Indicator of Maximum Radiation Dose to the Skin During Percutaneous Coronary Intervention

OBJECTIVE A number of cases of radiation-associated patient skin injury during percutaneous coronary intervention (PCI) have been reported. To protect against this complication, maximum skin dose to the patient should be monitored in real time. Unfortunately, in most cardiac intervention procedures, real-time monitoring of maximum skin dose is not possible. Angiographic X-ray units, however, display the patients total entrance skin dose in real time. We therefore investigated the relation between maximum skin dose and total entrance skin dose to determine whether total entrance skin dose can be used to estimate maximum skin dose during PCI. MATERIALS AND METHODS The dose-area product was measured, and maximum skin dose and total entrance skin dose were calculated with a skin-dose-mapping software program. The target vessels of 194 PCI procedures were divided into four groups according to the American Heart Association (AHA) segment system. RESULTS The maximum skin dose constituted 48%, 52%, 50%, and 52% of the total entrance skin dose during PCI on AHA segments 1-3, 4, 5-10, and 11-15, respectively. There were significant correlations between maximum skin dose and total entrance skin dose during PCI (r = 0.894, 0.935, 0.859, and 0.898 for segments 1-3, 4, 5-10, and 11-15, respectively; p < 0.001). CONCLUSION Maximum skin dose during PCI is approximately 50% of the total entrance skin dose for each target vessel. Correlation between the two doses was very good. Total entrance skin dose is an effective predictor of maximum skin dose during PCI when the formula used is maximum skin dose = 0.5 x total entrance skin dose. Our results provide useful information for avoiding deterministic radiation skin injury to patients undergoing PCI.

Reduced compression mammography to reduce breast pain

This study evaluated whether reduced compression mammography to relieve breast tenderness is feasible. Women can better tolerate a compression force of approximately 90 N in mammography. The breast thickness increased approximately 3 mm when the compression force was reduced to 90 N, and although the radiation dose increased approximately 20%, the image quality was identical to that with standard compression. Many patients experience breast pain with a compression force of 120 N. Reduced compression force mammography is acceptable in women whose breasts are particularly sensitive.

Evaluation of Patient Radiation Dose during Cardiac Interventional Procedures: What Is the Most Effective Method?

Cardiac interventional radiology has lower risks than surgical procedures. This is despite the fact that radiation doses from cardiac intervention procedures are the highest of any commonly performed general X-ray examination. Maximum radiation skin doses (MSDs) should be determined to avoid radiation-associated skin injuries in patients undergoing cardiac intervention procedures. However, real-time evaluation of MSD is unavailable for many cardiac intervention procedures. This review describes methods of determining MSD during cardiac intervention procedures. Currently, in most cardiac intervention procedures, real-time measuring of MSD is not feasible. Thus, we recommend that physicians record the patients total entrance skin dose, such as the dose at the interventional reference point when it can be monitored, in order to estimate MSD in intervention procedures.

Indicators of the maximum radiation dose to the skin during percutaneous coronary intervention in different target vessels

Objectives: To evaluate whether the maximum radiation dose to the patients skin (MSD) can be estimated during percutaneous coronary intervention (PCI) procedures, we investigated the relationship between the MSD and fluoroscopic time, dose‐area product (DAP), and body weight, separately analyzing the relationships for different target vessels. Background: Many cases of skin injury caused by excessive radiation exposure during cardiac intervention procedures have been reported. However, real‐time maximum‐dose monitoring of the skin is unavailable for many cardiac intervention procedures. Methods: We studied 197 consecutive PCI procedures that involved a single target vessel and were conducted. The DAP was measured, and the MSD was calculated by a skin‐dose mapping software program (Caregraph). The target vessels of the PCI procedures were divided into four groups based on the AHA classification system: AHA 5–10, left anterior descending artery domain (LAD), AHA 11–15, left circumflex artery domain (LCx), AHA 1–3 = R 1–3, and AHA 4 = R 4. Results: The correlation coefficient (r) between the MSD and fluoroscopic time was higher for the right coronary artery (RCA) vessels (R 1–3, 0.852; R 4, 0.715) than for the left coronary artery (LCA) vessels (LAD, 0.527; LCx, 0.646), and the r value between the MSD and DAP was higher for the RCA vessels (R 1–3, 0.871; R 4, 0.898) than for the LCA vessels (LAD, 0.628; LCx, 0.694). Similarly, the correlation coefficient between the MSD and weight × fluoroscopic time (WFP) was higher for the RCA vessels (R 1–3, 0.874; R 4, 0.807) than for the LCA vessels (LAD, 0.551; LCx, 0.735). Conclusions: The DAP and WFP can be used to estimate the MSD during PCI in the RCA but not in the LCA, especially the LAD.

Optimizing patient radiation dose in intervention procedures.

Although numerous patients derive great benefit from interventional procedures, a serious disadvantage associated with interventional procedures is patient radiation dose. Therefore, interventionalists should be aware of how to reduce the radiation dose to their patients. Currently, no conclusive method for reducing radiation dose is available for interventional procedures; hence, it is necessary to combine various methods. In addition, in order to reduce the radiation injury risk in interventional procedures, evaluation of patient radiation dose is essential. Generally, the tradeoff for a decrease in radiation dose is a loss in image performance. Therefore, optimization of radiation dose and image performance is important in interventional procedures.

Clarifying and Visualizing Sources of Staff-Received Scattered Radiation in Interventional Procedures

OBJECTIVE Interventional radiology tends to involve long procedures (i.e., long fluoroscopic times). Therefore, radiation protection for interventional radiology physicians and staff is an important issue. We examine and identify sources of staff-received scattered radiation in an interventional radiology system using a pinhole camera method. CONCLUSION Physicians and staff are exposed primarily to two sources of scattered radiation: radiation scattered from the patient and radiation from the cover of the x-ray beam collimating device. Those who stand close to the patient and the x-ray beam collimating device, where scattered radiation is higher, have higher radiation doses. Thus, radiation protection during interventional radiology procedures is an important problem.