Table 4. Technical factors related to the DAP (Gy cm−2) at each fluoroscopy sequence delivered during 100 percutaneous transluminal coronary angioplasties performed by 3 practitioners.
| Factors | n | Estimations on log(dose) scalea |
Back-transformed coefficients | p-value | |
| Coefficients | 95% CI | ||||
| Constant | 1550 | 1.35 | (0.15, 2.56)b | 3.86 | – |
| Cinematography settings | <0.0001 | ||||
| “Low dose” mode at 12.5 fr s–1 | 1004 | 0 | reference | ||
| “Low dose” mode at 25 fr s–1 | 154 | 0.69 | (0.40, 1.00)b | 1.99 | |
| “High dose” mode at 12.5 fr s–1 | 305 | 0.38 | (0.19, 0.57)b | 1.46 | |
| “High dose” mode at 25 fr s–1 | 87 | 0.77 | (0.46, 1.08)b | 2.16 | |
| Focus–intensifier distance (cm) | 1550 | −0.00 | (−0.01, 0.01) | −1.00 | 0.30 |
| Intensifier field size (cm) | <0.0001 | ||||
| 14 | 131 | 0 | reference | ||
| 17 | 1401 | 0.43 | (0.23, 0.62)b | 1.53 | |
| 23 | 18 | 0.45 | (−0.01, 0.91) | 1.57 | |
| Collimation | <0.0001 | ||||
| No | 545 | 0 | reference | ||
| Yes | 1005 | −0.70 | (−0.82, −0.58)b | −2.01 | |
| X-ray tube orientation (vs mean effect of beam orientation) | <0.0001 | ||||
| CAUD/RAO (25–55)°C | 84 | 0.29 | (0.07, 0.51)b | 1.34 | |
| CAUD/RAO (15-25)°C | 80 | −0.15 | (−0.37, 0.06) | −1.17 | |
| CAUD/RAO (5-15)°C | 81 | −0.07 | (−0.30, 0.15) | −1.07 | |
| CAUD/PA | 112 | 0.11 | (−0.09, 0.32) | 1.12 | |
| CAUD/LAO (5-25)°C | 62 | −0.00 | (−0.33, 0.33) | −1.00 | |
| CAUD/LAO (25–35)°C | 49 | 0.21 | (−0.08, 0.50) | 1.64 | |
| CAUD/LAO (35–100)°C | 115 | 0.31 | (0.13, 0.49)b | 1.18 | |
| PA/RAO (5–55)°C | 34 | −0.53 | (−0.85, −0.22)b | −1.70 | |
| PA/PA | 30 | −0.12 | (−0.53, 0.29) | −1.13 | |
| PA/LAO (5-25)°C | 47 | −0.18 | (−0.54, 0.18) | −1.20 | |
| PA/LAO (25–35)°C | 108 | −0.09 | (−0.31, 0.14) | −1.09 | |
| PA/LAO (35–55)°C | 45 | −0.05 | (−0.34, 0.25) | −1.05 | |
| PA/LAO (55–100)°C | 117 | −0.17 | (−0.37, 0.02) | −1.20 | |
| CRAN/RAO (35–55)°C | 60 | −0.21 | (−0.47, 0.05) | −1.24 | |
| CRAN/RAO (25–35)°C | 70 | 0.06 | (−0.20, 0.33) | 1.07 | |
| CRAN/RAO (15-25)°C | 104 | 0.05 | (−0.16, 0.26) | 1.05 | |
| CRAN (35–45)°C/RAO (5-15)°C | 72 | 0.16 | (−0.09, 0.42) | 1.18 | |
| CRAN (5–35)°C/RAO (5-15)°C | 65 | −0.18 | (−0.48, 0.12) | −1.20 | |
| CRAN/PA | 72 | 0.01 | (−0.22, 0.24) | 1.01 | |
| CRAN/LAO (5-25)°C | 68 | −0.16 | (−0.43, 0.12) | −1.17 | |
| CRAN/LAO (25–35)°C | 37 | 0.50 | (0.16, 0.83)b | 1.64 | |
| CRAN/LAO (35–100)°C | 38 | 0.17 | (−0.14, 0.48) | 1.18 | |
| Sequence | 1550 | −0.01 | (−0.01, 0.00) | −1.01 | 0.08 |
95% CI, confidence interval; CAUD, caudal; CRAN, cranial; fr, frames; LAO, left anterior oblique; PA, posters-anterior; RAO, right anterior oblique.
aBoxox transformed coefficients (λ=0).
bConfidence interval that does not include 0. Maximum likelihood estimation criterion; standard errors in the random part are 0.59 for the practitioners intercept, 0.41 for the patients intercept and 0.83 for the residual error. Residual error variance of a previous null model was 0.79. The residual variance proportion explained by the covariates is 13.2%; the practitioners' random intercept variance decreased by 36.9% while introducing the covariates.