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1 Study on accurate dose mapping system with radiophotoluminescence glass dosimeter (RPLD) measuring the direct patient entrance dose in cardiac interventional procedures. Poster No.: C-0687 Congress: ECR 2013 Type: Scientific Exhibit Authors: M. Kato 1, K. Chida 2, T. Moritake 3, Y. Koguchi 4, T. Sato 1, H. Oosaka 1, T. Tosa 1, K. Kadowaki 1 ; 1 Akita/JP, 2 Sendai/JP, 3 Tsukuba/JP, 4 Higashiibarakigun Oaraimachi/JP Keywords: DOI: Education and training, Dosimetric comparison, Radiation safety, Physics, Dosimetry, Percutaneous, Catheter arteriography, Radioprotection / Radiation dose, Radiation physics, Cardiac /ecr2013/C-0687 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not Page 1 of 21

2 available in the pdf version of presentations. Page 2 of 21

3 Purpose Background: Cardiac interventional radiology procedures such as percutaneous coronary intervention (PCI) have been increasing year by year because of their low invasiveness compared to surgical operations such as coronary artery bypass grafts. Although numerous case reports of patient radiation injury resulting from PCI are increasingly being published, these reports likely represent a small fraction of the actual cases. Once, we had examined the prospective study to identify radiation injuries after PCI. Although mild erythema occurred (Fig.1), we observed six cases (1.5%) of radiation skin injury in 400 consecutive PCIs. The occurrence rate of skin injury in our study was higher than previously reported. Learning objectives: Radiation skin injuries have been still reported. There is a necessity to measure the patient entrance skin dose (ESD), but accurate dose measurement method has not been established. We examined to build a direct measurement system to determine accurate ESD and its mapping using multiple radiophotoluminescence glass dosimeters (RPLDs) in cardiac interventional procedure. Page 3 of 21

4 Images for this section: Fig. 1: 62-year-old men: body weight 87.0 kg, height 169cm. (a) Erythema continued for 6 months after PCI. (b and c) Erythema gradually lessened and skin pigmentation became normal. (b: 13 months after PCI. C: 15 months after PCI. ) Page 4 of 21

5 Methods and Materials Direct measurement system: There is a necessity to measure the ESD and its mapping, but accurate dose measurement method has not been established. We devised a accurate measurement system for ESD and maximum patient skin dose (MSD), using many RPLDs in an array. In this study, we examined the fundamental characteristics of an RPLD. Materials: The x-ray device used in this study was a digital cine single-plane x-ray system (Infinix Celeve-i, Toshiba, Japan) with a flat-panel detector (FPD). This equipment includes a fixed additional filter (0.06 mm Tantalum). The total filtration of this equipment is 1.1 mm Al mm Ta. RPLDs made of silver-activated phosphate glass used in this study were 12 mm in length and 1.5 mm in diameter with a plastic capsule (GD-302M, Chiyoda Technol Corporation, Japan), and measurement/readout system of RPLD was Dose Ace FGD-1000 (Chiyoda Technol Corporation). The equipment uses a pulsed UV laser measurement technique. RPLDs: RPLDs can provide highly accurate measurement from low levels of natural radiation to high levels of radiotherapy (10µGy to 10Gy). RPLDs have no fading effect, compared to TLD. RPLDs are usually equipped with energy compensation filters made of tin. Radiopaque materials will be viewed in the display monitor and impeded the PCI procedure. In this study, we chose the GD-302M with no energy compensation filter as the RPLDs. Reference dosimeter: Reference measurements were made using an ionization chamber, model 9015 (Fig.2), manufactured by Radcal Corp. (California, USA), and a calibrated (reference: traceable from the national standard exposure) thimble-type 6 ml ion chamber with ±5% energy dependence in the 40 to 80 kev range. Page 5 of 21

6 GD-302M measurements were compared to measurements obtained with a reference ionization chamber. For each measurement, five GD-302M dosimeters were irradiated in free air (Fig.2). The average ± SD value based on measurements of the elements of the GD-302M dosimeters were determined. Methods: Effective energy dependence: The tube voltage range for PCI in our hospital is 70 to 120 kvp. We measured the effective energy for a tube voltage of 70 to 120kVp (70, 80, 90, 100, 110, and 120 kvp) using the aluminum half-value layer (HVL) measurement method. We also evaluated the calibration factor for the GD-302M in the 70 to 120 kvp range. The factor was calculated as: Calibration factor = reference ion chamber measurement / GD-302M measurement. Dose dependence and the dose-rate dependence: The dose dependence was measured at five different doses (0.1, 0.5, 1.0, 2.0, 3.0Gy) using a tube voltage of 80 kvp. The dose-rate dependence, at a fixed voltage (80kVp) and time (100ms), was measured by varying the tube current from 1 to 1000 ma. Angular dependence: The angular dependence of the GD-302M dosimeter in the short and long axes was measured at a tube voltage of 90 kvp. We assumed at seven points (0, ±30, ±60, and ±90 ) for each of the axes (Fig.3). The angular dependence was evaluated with the 0 measurement used as the reference value. Page 6 of 21

7 Images for this section: Fig. 2: Measurement geometry in this study (energy dependence, dose dependence, and the dose-rate dependence of the GD-302M dosimeter ) Page 7 of 21

8 Fig. 3: Angular dependence in the short and long axes Page 8 of 21

9 Results effective energy (kev) The relationship between effective energy (kev) obtained HVL and tube voltage of 70 to 120 kvp is shown in Figure 4. The effective energies at 70, 80, 90, 100, 110, and 120 kvp were 40.8, 42.2, 44.7, 46.9, 48.1, and 50.5 kev, respectively. energy dependence (kev) The energy dependence (kev) is shown in Figure 5. The GD-302M showed high sensitivity, and the sensitivity tended to decrease a little as effective energy increased. The calibration factor of the GD-302M is shown in Figure 6. dose dependence The dose dependence of the GD-302M is shown in Figure 7. The GD-302M showed excellent linearity, with R 2 > dose rate dependence The dose rate dependence is shown in Figure 8. The GD-302M showed excellent linearity, with R 2 > 0.99 over a range of fold ( ). angular dependence The angular dependence in the short annd long axes is shown in Figure 9. GD-302M showed no angular dependence in the short axis. GD-302M showed reliable dose response at angles between 0 and ± 60 in the long axis. At angles of 90, the dose response varied widely. direct dose measurement method The irradiation fields were confirmed by using the radiochromic dosimetry films in cardiac interventional phantom experiment, and placement of RPLDs was optimized (Figure 10-11). We made a dosimetry gown, which has small pockets to insert the RPLD chips, to measure the accurate ESD and its mapping. Page 9 of 21

10 Images for this section: Fig. 4: Relationship between effective energy (kev) obtained HVL and tube voltage of 70 to 120 kvp. Page 10 of 21

11 Fig. 5: Energy dependence (kev). Page 11 of 21

12 Fig. 6: Calibration factor of the GD-302M. Calibration factor = reference ion chamber measurement / GD-302M measurement. Page 12 of 21

13 Fig. 7: Dose dependence of the GD-302M. Page 13 of 21

14 Fig. 8: Dose rate dependence of the GD-302M. Page 14 of 21

15 Fig. 9: Angular dependence in the short and long axes. Page 15 of 21

16 Fig. 10: Confirmation test of irradiation field with radiochromic dosimetry film. Page 16 of 21

17 Fig. 11: Optimization of placement. Page 17 of 21

18 Conclusion X-ray permeable RPLD (with no thin filter) did not interfere with PCI procedure. The RPLD also had good fundamental performance characteristics. Although the RPLD had little energy dependence, it showed excellent dose and dose-rate linearity, and good angular dependence. Furthermore, the energy dependence can be corrected using calibration factors. We expect that this direct measurement method using RPLDs dosimetry gown can provide accurate ESD and MSD measurements in cardiac IRs. Page 18 of 21

19 References 1. International Commission on Radiological Protection. Avoidance of radiation injuries from medical interventional procedures. ICRP Publication 85. (Ann. ICRP 30)(2000). 2. Tsapaki V, Kottou S, Vano E, Parviainen T, Padovani R, Dowling A, Molfetas M, Neofotistou V. Correlation of patient and staff doses in interventional cardiology. Radiat Prot Dosimetry. 117, (2005). 3. Balter S. Stray radiation in the cardiac catheterisation laboratory. Radiat Prot Dosimetry. 94, (2001). 4. Padovani R, Bernardi G, Quai E, Signor M, Toh HS, Morocutti G, and Spedicato L. Retrospective evaluation of occurrence of skin injuries in interventional cardiac procedures. Radiat Prot Dosimetry.117, (2005). 5. Balter S, Hopewell JW, Miller DL, Wagner LK, and Zelefsky MJ. Fluoroscopically guided interventional procedures: a review of radiation effects on patients' skin and hair. Radiology. 143, (2010). 6. KatoM, Koichi Chida K, Sato T, Oosaka H, Tosa T, Munehisa M, and Kadowaki K. The necessity of follow up for radiation skin injuries in patients after percutaneous coronary interventions: radiation skin injuries will often be overlooked clinically. Acta Radiol. 53, (2012). 7. Hwang E, Gaxiola E, Vlietstra RE, Brenner A, Ebersole D, and Browne K. Real-time measurement of skin radiation during cardiac catheterization. Cathet Cardiovasc Diagn 43, (1998). 8. Stephen Balter. Methods for measuring fluoroscopic skin dose. Pediatr Radiol. 36, (2006). 9. Stephen Balter. Managing Patient Dose in Interventional Cardiology. Catheter Cardiovasc Interv. 70, (2007). 10. Chida K, Saito H, Otani H, Kohzuki M, Takahashi S, Yamada S, Shirato K, and Zuguchi M. Relationship between fluoroscopic time, dose-area product, body weight, and maximum radiation skin dose in cardiac interventional procedures. Am J Roentgenol. 186, (2006). 11. Cusma JT, Bell MR, Wondrow MA, Taubel JP, Holmes DR Jr. Real-time measurement of radiation exposure to patients during diagnostic coronary angiography and percutaneous interventional procedures. J Am Coll Cardiol. 33, (1999). 12. Ying CK, Kandaiya S. Patient skin dose measurements during coronary interventional procedures using Gafchromic film. J Radiol Prot. 30, (2010). 13. Giordano C, D'Ercole L, Gobbi R, Bocchiola M, Passerini F. Coronary angiography and percutaneous transluminal coronary angioplasty procedures: Evaluation of patients' maximum skin dose using Gafchromic films and a comparison of local levels with reference levels proposed in the literature. Phys Med. 26, (2010). Page 19 of 21

20 14. Chida K, Kagaya Y, Saito H, Takai Y, Takahashi S, Yamada S, Kohzuki M, Zuguchi M. Total entrance skin dose: an effective indicator of maximum radiation dose to the skin during percutaneous coronary intervention. Am J Roentgenol. 189, (2007). 15. Chida K, Saito H, Zuguchi M, Shirotori K, Kumagai S. Matsubara K, and Kohzuki M. Does digital acquisition reduce patients' skin dose in cardiac interventional procedures? An experimental study. Am J Roentgeno. 183, (2004). 16. Chida K, Kato M, Saito H, Ishibashi T, Takahashi S, Kohzuki M, and Zuguchi M. Optimizing patient radiation dose in intervention procedures. Acta Radiol. 51, (2010). 17. Nishizawa K, Moritake T, Matsumaru Y, Tsuboi K, Iwai K. Dose measurement for patients and physicians using a glass dosemeter during endovascular treatment for brain disease. Radiat Prot Dosimetry. 107, (2003). 18. Moritake T, Matsumaru Y, Takigawa T, Nishizawa K, Matsumura A, Tsuboi K. Dose measurement on both patients and operators during neurointerventional procedures using photoluminescence glass dosimeters. AJNR Am J Neuroradiol.29, (2008). 19. Manninen AL, Koivula A, Nieminen MT. The applicability of radiophotoluminescence dosemeter (RPLD) for measuring medical radiation (MR) doses. Radiat Prot Dosimetry. 151, 1-9 (2012). 20. Kato M, Chida K, Sato T, Oosaka H, Tosa T, Kadowaki K. Evaluating the maximum patient radiation dose in cardiac interventional procedures. Radiat Prot Dosimetry. 143, (2011). Page 20 of 21

21 Personal Information Mamoru Kato, 1,2# MS, Koichi Chida, 2 PhD, Takashi Moritake, 3 MD, PhD, Yasuhiro Koguchi, 4 MS, Tadaya Sato, 1 MD, Hajime Oosaka, 1 BS, Tetsuo Tosa, 1 MS, and Ken Kadowaki, 1 MD 1 Akita Medical Center, 6-17 Senshukubota, Akita, Akita , Japan. 2 Tohoku University Graduate School of Medicine. 2-1 Seiryo, Aoba, Sendai, Miyagi , Japan. 3 University of Tsukuba, Tennohdai, Tsukuba, Ibaraki , Japan 4 Oarai Research Center, Chiyoda Technol Corporation, 3681 Naritacho, Higashiibarakigun Oaraimachi, Ibaraki , Japan # Correspondence to: Mamoru Kato, Department of Medical Technology, Akita Medical Center, 6-17 Senshukubota, Akita, Akita , Japan Tel , Fax , katou@amc.or.jp Page 21 of 21