USING CVP-2 (CREATIVE VALUABLE
PROTECTOR-2)
RADIATION FİLTER WITH C-ARM
FLUOROSCOPY DEVICE
(Radiologic Assessment Report)
Prepared By
Assoc. Prof. Aydın Parmaksız
SANAEM-SFB Protection Against Radiation Unit Emine Bulur
SANAEM-SFB Protection Against Radiation Unit Miray Başdoğan
SANAEM-SFB Protection Against Radiation Unit Assoc. Prof. Gökçe Kaan Ataç
Ufuk University-School of Medicine Radiology Department Ufuk Turpçu
Ufuk University-School of Medicine Radiology Department Dr. Sema Şen
SANAEM-SFB Dose Monitoring Unit Ankara-2018
R.T. Ministry of Health has requested for the “CVP-2 (Creative Valuable Protector-2) Radiation Filter” called product wished to be launched by the company with the title “Aymed Medical Teknoloji San. ve Tic. Ltd. Şti.” with its letter dated 20/12/2017 no 78704445-000-E.254790 by the Turkey Medicine and Medical Device Institution Presidency, regarding whether it performs the functions declared, and if it does the performance of the dosimetry tests for protection against radiation and our comments on the evaluation its evaluation for its usage in our country, as there is no other clinical data or assessment other than the dosimetry study the manufacturer declared in which the device is defined as a device for protection of the patient and operators from the harmful effects of the radiation when the device is used in the C-arm fluoroscopy devices.
In this report, there are the radiologic assessments regarding usage of the CVP-2 Radiation Filter and the radiation doses the patient and the personnel can receive, as the result of the radiations performed under the operation room conditions for the scenarios where the CVP-2 Radiation Filter is attached without adaptor and not attached to the C-arm fluoroscopy devices used in the Söğütözü Bayundur Hospital and Ufuk University Dr. Rıdvan Ege Hospital operation rooms belonging to the Bayındır Health Group.
Doç. Dr. Aydın PARMAKSIZ Specialist
Doç. Dr. Gökçe KAAN ATAÇ Radiology Specialist fukTURPÇU Radiology Technician Emine BULUR Physicist Miray BAŞDOGAN Physics Engineer Dr. Sema Sen Physicists
Index
1. Introduction………3
1.1 CVP-2 (Creative Valuable Protector-2) Radiation Filter………..…………5
2. Tools and Method………..7
3. Findings………..………12
3.1 Patient Dose ………..……….12
3.2 Personnel Dose………12
3.3 Image Quality……….13
4. Results and Conclusion………..19
ı.
IntroductionsIn medical radiation applications, the most widely used ionizing radiation is the X-rays. The applications with C-arm fluoroscopy devices used as the X-ray source in operation rooms, forms an important part of the radiation doses the patient and the radiation personnel are exposed to. The use of Fluoroscopy for leading interventional radiology operations, started in 1980s, is very widespread today. In fluoroscopy and interventional operations performed in guidance of fluoroscopy, the doctor performing the operation can monitor in motion the internal structure of the body and the organs of the patient with the x-ray imaging technique where the real time images are taken. In the fluoroscopy examinations and interventional operations performed in guidance of fluoroscopy where the distance between the x-ray tube and the patient and the structural armor is not among the options of the doctor, when the radiation is used the close physical contact with the patient should be maintained.
In order for the patient to receive limited amount of radiation, it is required that the minimum possible X-ray field is used and the tube positioning is made accurately. With the total filtration in front of the X-ray bundle the very low energy part of the bundle is stopped before reaching the patient. As X-ray bundle collimation being larger than necessary shall create additional scattered radiation, the image quality will be disrupted. In fluoroscopy examinations the patient dose increases depending on the radiation period. Taking some simple measures the patient dose can be diminished considerably.
An important factor in occupational radiation is the correct orientation of the X-ray tube and the image collector. In the operation rooms, when using C-arm fluoroscopy device, X-Ray tube should be under the table. In this case, the primary and secondary radiation doses, depending on the table level, when the tube is under the table (≈45cm), increases approximately 2-3 folds and when it is over the table level it drops to half. For the approximately vertical (90o) orientations for the X-ray tube under the table, the occupational exposure of the operators is less as the scattering from the patient shall be minimum. Similarly in close side projections, standing on the side of the patient who is against the X-ray tube shall decrease more the occupational exposure due to same reason. The personnel applying such procedures should have received protection against radiation training and should understand well the effects of all related factor. Also, it is important to perform continuously and accurately the monitoring of personal dose. The scattered radiation can be weakened by the lead coats, led equivalent googles and clothing like thyroid protectors worn by the personnel and protective tools placed between the patient and the
the dose the surgeon can be exposed due to scattered radiation 90% and 99% respectively, depending on the X-ray energy [1]. It is expected that the doctor and nurse working closest to the device without wearing a led coat should be exposed to the highest radiation dose. As the eye lens is very sensitive to the radiation [2], the eye doses for the ones working closest to the patient can be intolerably high. For this reason, protective led googles, especially googles with side protectors, shall cut the scattering from the patient and can cause reduction in eye dose up to 80% [3]. The ceiling hanged protective screens providing significant amount of radiation protection is dependent on their correct positioning. These screens provide protection only to a part of the body (typically torso, head and eyes) and using these besides wearing protective clothing can remove the need (requirement) to use additional protective googles. However, due to clinical reasons sometimes protective screens cannot be used. The protective led plates mounted on the table, whereas, provide additional protection to the lower part of the body and legs.
The technician and other operation room personnel working behind the lead screen have very low probability to be exposed to high radiation. It is very important that the operation room personnel working with the C-arm fluoroscopy device absolutely use radiation protection clothing, gonad, thyroid and eye protectors and that the other personnel to work behind the protective screens [4]. The personal protective equipment used in protection against radiation must be used properly.
In the fluoroscopy and interventional operations performed in guidance of fluoroscopy, the hands of the operator can be in the primary X-ray bundle unintentionally. As the exposure of the protective gloves to the primary bundle increases the radiation dose automatically, this can be dangerous. The protective gloves can slow down the operation and create a false security feeling. In this case, the personnel should be trained to keep the hands out of the primary bundle. Having the X-ray tube under the table, as the primary X-ray bundle is weakened by the patient’s body, provides the hands to be protected best when they need to be close to the X-ray field.
In the 2013/59/ Eurotom Directive dated 5 December 2013 determining the basic safety standards for protection against the hazards of exposure to the ionizing radiation, the scientific developments realized since the previous Basic Safety Standards (BSS) Directive and the new suggestions of the International Commission of Radiation Protection, ICRP given in the paper no 103 issued in 2007 [2, 5]. The recent scientific knowledge on tissue reactions indicates that the radiation workers’ eye lens should be protected better. The new Directive no 2013/59 issued after the new suggestions of ICRP changed the dose limit for eye lens from 150mSv/year to 20mSv/year, the modifications on justification, patient information, the importance of dose reporting and the diagnostic reference levels are clarified [6].
1.1 CVP-2 (Creative Valuable Protector-2) Radiation Filter
In the document given as attached to the letter dated 20/12/2017 no 78704445-000-E.254790 by R.T. Ministry of Health, Turkey Medicine and Medical Device Institution Presidency, the product called “CVP-2 radiation filter” [Figure 1] is claimed to;
• Decrease the radiation dose the patient and the personnel are exposed to by 72% when X-ray tube is at 90o over the table,
• Increase the effectiveness of the conventional X-ray protection equipment like protective googles and led vest and to provide a significantly safe working environment,
• Provide protection of hands, feet, head, skin and other areas the X-ray protection equipment cannot protect,
• Give higher contrast images when the CVP-2 filter is on compared to when it is not, i.e. increasing contrast.
In this study, in order to evaluate the claims given above, the radiation doses the personnel and the patient may be exposed to as the result of radiations performed under the real operation room conditions are measured, via placing the CVP-2 Radiation Filter without adaptor to the Fluoroscopy devices at the Söğütözü Bayundur Hospital and Ufuk University Dr. Rıdvan Ege Hospital belonging to the Bayındır Health Group and the assessments on these measurements are reported.
2. Tools and Method
As the result of meeting with the official of the related firm, the list of C-arm fluoroscopy devices to which the CVP-2 filter can be attached with or without an adaptor is determined for Ankara. This study is performed with the GE Innova Brand 2 fluoroscopy devises in use at the operation rooms of Söğütözü Bayundur Hospital and Ufuk University Dr. Rıdvan Ege Hospital operation rooms belonging to the Bayındır Health Group, human equivalent Rando Phantom simulating the patient, via attaching CVP-2 radiation filter without adaptor, using the X-ray tube under the table (90o) [Figure 2]. In the studies made regarding the radiation protection of the personnel in the literature, as the X-ray tube being used under the table decreases the personnel dose, the study is performed in this projection (X-ray tube under the table 90o) [7].
Figure 2. C-arm fluoroscopy device and Rando Phantom
The positions of the patient and the personnel in the operation rooms during the fluoroscopy and interventional operations performed in guidance of fluoroscopy are determined and the measurement equipment are prepared and positioned [Figure 3]. Four mannequins are used for the doctor performing fluoroscopy, the assisting doctor, the anesthetist and nurse/technician [Figure 4].
Figure 3. Preparation of operation room for measurement
Figure 5. Radcal 9015 Ion Chamber
Radiation doses are measured first of all with 66 cc ion chamber Radcal 9015 [Figure 5]. With the ring dosimeters placed at the eye, thyroid, gonad, abdomen and skin entry regions of the Rando Phantom representing the standard patient, the doses the patient is exposed to in the cases where the CVP-2 filter is used and not used. Similarly, in order to calculate the gonad region and whole body dose of the personnel working in the operation room, three Thermoluminescence Dosimeters (TLD) are placed over and under protective coat at chest region and gonad region. At the same time, three ring dosimeters used for each region in dose measurements over and under protective equipment for the eye and thyroid and extremity regions of the mannequins representing the personnel (Figure 6). TL chips provide the accurate measurement of the actual radiation dose at the points they are applied.
In the Panasonic brand TL Dosimeters used in measurements, there are LiB4O7:Cu and
CaSO4:Tm thermosluminescence crystals and proper filters to calculate dose independent of
the energy. With these dosimeters gama (γ), X-rays, beta (β) and neutron doses in the energy range of 0.1 mSv-10Sv and 20 keV-1.25 MeV, and with the ring dosimeters gama (γ), X-rays, beta (β) doses in the energy range of 0.1 mSv-10Sv and 20 keV-1.25 MeV can be measured. The dosimeters used in this study are evaluated in the Panasonic brand UD716 model TL reader.
Sarayköy Nuclear Research and Training Center (SANAEM), Health Physics Department, TL Dosimetry System and the Ring Dosimetry System where the dosimetry measurements are assessed, was accredited by TUBİTAK on 04 May 2009 and 28 August 2013 respectively.
In the created scenario, the measurements are taken while the X-ray tube is under the table and the positions of the personnel are kept stable, for the cases when the CVP-2 filter is mounted and not, and the radiation parameters are taken as 85 kV, 3 mA and 10 minutes. In the measurements made with the fluoroscopy image quality phantom [Figure 7] at 45-110 kV range (5 kV increments), the same radiation parameters are used, and the assessments of the images are made clinically. Also the doses are measured with the 6cc ion chamber used together with the image quality phantom.
In this study, as the measurement of the radiation doses the operation room personnel are exposed to due scattered radiation from the patient when the tube is over table (X-ray tube should be used under the table) and the mapping showing the radiation effect dependent on the angles after the CVP-2 application are not needed according to the clinical researches declared by the firm, no measurements, determinations and assessment are not performed related to these issues in this report.
The assessment and results in this report are valid for the condition in which the CVP-2 radiation filter is attached on C-arm fluoroscopy devices without adaptor. It is recommended that the study is repeated with a new scenario to be created for the condition in which the mentioned filter is attached on C-arm fluoroscopy devices with adaptor.
3. Findings
3.1 Patient Dose
Due to the total filtration in front of the X-ray bundle the very low energy part of the bundle is stopped before reaching the patient. When 600 seconds fluoroscopy is performed using Rando Phantom representing the patient at 85 kV and 8 mA, according to the ring dosimeter results placed at the waist region of the Rando Phantom representing the standard patient exposed to the primary ray bundle; in radiations performed using CVP-2 filter, compared to the condition where the filter is not used, the skin entry doses are found to be 63.7% lower. At same radiation parameters, in the measurements made directly using 66cc ion chamber Radcal 9015, in radiations performed using CVP-2 filter, compared to the condition where the filter is not used, the skin entry doses are found to be 70.8% lower.
3.2 Personnel Dose
During the same operation applied when the X-ray tube is under the table (when 90o)
in cases when CVP-2 filter is attached and not (with Rando Phantom, using 85kV and 8mA at total of 600 seconds), the doses of radiation workers are measured with TL and ring dosimeters. According to the case when the CVP-2 filter is attached, the radiation decreasing rates of the measured results are given in Table 1 as %.
Table 1. CVP-2 filter attached, radiation reduction rates (%) Fluoroscopy performing doctor
(Mannequin-1) Assisting Doctor (Mannequin-2) (Mannequin-3) Anesthetist
D os im et er pl aced Re gi on Eye (r ight -le ft av r.) Thyr oi d H and ( righ t-le ft av r.) Fe et (ri gh t-le ft av r.) G ona d W hol e Body Eye (r ight -le ft av r.) Thyr oi d H and ( righ t-le ft av r.) Fe et (ri gh t-le ft av r.) G ona d W hol e Body Eye (r ight -le ft av r.) Thyr oi d H and ( righ t-le ft av r.) Fe et (ri gh t-le ft av r.) G ona d W hol e Body Ra dia tio n Re duc tio n rat e (% ) 44 .5 85 .2 85 .9 73 .7 69 .5 79 .0 52 .1 36 .4 53 .1 30 .0 86 .2 28 .6 43 .2 30 .0 40 .0 69 .9 40 .0 40 .0
For the extremities the protective equipment are not used, in the case the CVP-2 filter is attached compared to when it is not, the radiation doses at the right and left hands of the fluoroscopy performing doctor (mannequin-1) are determined to be reduced 85.0% and 86.8% respectively. Similarly, when CVP-2 filter is used the right and left feet doses of the fluoroscopy performing doctor are determined to be reduced 85.3% and 62.1% respectively. When CVP-2 filter is used the right and left eyes doses of the fluoroscopy performing doctor are measured to be reduced 45.1% and 43.9% respectively. When CVP-2 filter is used,
compared to when it is not, the radiation doses of the fluoroscopy performing doctor are measured to be reduced at thyroid by 85.2% and at gonad region by 69.5% and the dose of the whole body is determined to be reduced by 79.0%.(40cm from X-ray axis, 90︒)
In cases the CVP-2 filter is used, compared to when it is not, the radiation doses at the right and left eyes of the assisting doctor (mannequin-2) are determined to be reduced 48.3% and 55.8% respectively. When CVP-2 filter is used the hand and feet doses of assisting doctor are determined to be reduced 53.1% and 30.0% respectively. Similarly, when CVP-2 filter is used the radiation doses of the assisting doctor are measured to be reduced at thyroid by 36.4%, at gonad region by 68.2% and at whole body by 28.6%.(100cm from X-ray axis, 170︒)
In cases the CVP-2 filter is used, compared to when it is not, the radiation doses at the right and left eyes of the anesthetist (mannequin-3) are determined to be reduced 46.4% and 40.0% respectively. When CVP-2 filter is used the doses of assisting doctor are determined to be reduced at eye by 40.0% and at right and left feet 68.7% and 71.1% respectively. When CVP-2 filter is used the radiation doses of the anesthetist are measured to be reduced at thyroid by 30.0%, at gonad region by 40.0% and at whole body by 40.0%.(70cm from X-ray axis, 0︒)
According to the assessed dosimeter results, in the case when CVP-2 filter is not present, the radiation dose decreasing rates of the led equivalent googles, thyroid protector and led coat used as personal protective equipment are found to be 84.5%, 78.0% and 93.0% respectively.
In this study as the mannequin 4 representing the nurse/technician is the farthest to the X-ray tube compared to the other personnel in the operation room, the measured radiation doses are found to be relatively low, and as the uncertainties at low radiation doses are high the doses results of the nurse/technician are not given.
3.3 Image Quality
The optimization principle in protection of the patient against radiation requires that the
the patient doses but also to protect the image quality [9].
In order to compare the image quality as with and without CVP-2, images are taken at fixed 8 mA and starting from 45 kV up to 110 kV with 5 kV increments and the patient doses are measured with ion chamber. The acquired images and the comparisons of the measured entry doses are given at Table 2.
In the images acquired at same radiation parameters for the cases where the CVP radiation filters are attached and not, it is seen that the CVP-2 radiation filter visibly increases the contrast resolution at the region the 1st and 2nd images at the quality phantom
scale are present, and does not create a distinct difference at the other regions. Also, when the results of the measurements with ion chamber are compared, determining two images where the image qualities are same, the dose values at the image with CVP-2, compared to the case where CVP-2 is not present, are determined to be reduced in the rate of 71.9% and 68.9% respectively [Table 3]. In this study, conforming with the literature, it is determined that the CVP-2 radiation filter increases the contrast resolution without disrupting image quality [10].
The graph of dose change with and without CVP-2 filter dependent on the Kilovolt is given on the Table 4. As seen on Table 4, different radiation doses with the ion chamber are measured for the case that the CVP-2 filter is not attached between 45-110 kV and for the case that the CVP-2 filter is attached between 70-110 kV. In the measurements made by using CVP-2 radiation filter, compared to the case without filter, lower radiation doses are measured.
45 kV, 0 μGy
Table 2. With and without CVP-2, at same radiation parameter, comparison of the image quality and the measured doses
50 kV, 85.9 μGy 55 kV, 133.3 μGy 60 kV, 185.0 μGy 65 kV, 239.4 μGy
45 kV, 0 μGy 50 kV, 0 μGy 55 kV, 0 μGy
60 kV, 0 μGy 65 kV, 0 μGy
WITH CVP-2
Table 2(cont.) With and without CVP-2, at same radiation parameter, comparison of the image quality and the measured doses
70 kV, 299.7 μGy 75 kV, 364.6 μGy 80 kV, 438.8 μGy 85 kV, 515.0 μGy 90 kV, 597.0 μGy
WITH CVP-2 90 kV, 211.4 μGy 85 kV, 171.4 μGy 80 kV, 136.4 μGy 75 kV, 102.6 μGy 70 kV, 69.6 μGy
Table 2(cont.) With and without CVP-2, at same radiation parameter, comparison of the image quality and the measured dose. 110 kV, 396.0 μGy 100 kV, 299.3 μGy 105 kV, 346.7 μGy 95 kV, 252.6 μGy 110 kV, 963.9 μGy 105 kV, 864.0 μGy 100 kV, 775.0 μGy 95 kV, 684.0 μGy
Table 3. With and without CVP-2, at same radiation parameter, comparison of the image quality and the measured doses
Table 4. With and without CVP-2 filter, Kilovolt dependent dose change [Dose (μGy) /Dose(μGy)(with CVP-2)]
Dose with CVP-2 (μGy) Dose(μGy) With CVP-2 80 kV, 136.4 μGy 75 kV, 102.6 μGy 75 kV, 364.6 μGy 80 kV, 438.8 μGy
4. Results and Conclusion
Knowing the radiation doses exposed during the fluoroscopy examinations and interventional operations performed in guidance of fluoroscopy is very important for the patient and radiation workers to be protected against radiation. According to the Basic Safety Standards-GSR Part 3 issued by the International Atomic Energy Agency and European Commission Euratom Directive no 2013/59 article 58 the radiation risks of the patient should be assessed. In this regard:
In the radiations performed using CVP-2 filter, for the standard patient (Rando Phantom), skin entry doses are found to be 63.7% lower compared to the case when CVP-2 filter is not used. Whereas in the measurements made using ion chamber the doses are determined to be 70.8% lower compared to the case when CVP-2 filter is not used. Thus, when the tube is at 90o position under the table, the patient skin entry doses measured with both TL Dosimeters and ion chamber are determined to be significantly decreased by the use of CVP-2 filter. As the X rays intensify at the desired region when CVP-2 filter is used, its use decreases the patient dose in clinical applications.
When the X-ray tube is under the table and CVP radiation filter is attached:
It is determined that the whole body dose of the fluoroscopy performing doctor with protective led coat at the closest distance to the tube (40 cm) measured with the TL Dosimeters is reduced in the rate of 79.0%. The radiation doses the right and left hands and right and left feet of the fluoroscopy performing doctor are exposed to are determined to be reduced by 85.0%, 86.8%, 58.3%, 62.1% respectively. Also, at right and left eyes 45.1% and 43.9% respectively, at the thyroid 85.2% and at gonad region 69.5% reduced doses are measured. As at closest position to the tube the fluoroscopy performing doctor is the person that is most exposed to the scattered radiation from the patient, the whole body dose is more compared to the other operation room personnel.
Of the assisting doctor the right and left eyes and hands and feet doses are determined to be lowered 48.3%, 55.8%, 53.1% and 30.0% respectively. At thyroid 36.4% and at gonad region 86.2% lower doses are measured.
Of the anesthetist the right and left eyes and hands and right and left feet doses are determined to be lowered 46.4%, 40.0%, 40.0%, 68.7% and 71.1% respectively. At thyroid 30.0% and at gonad region 40.0% and at whole body 40.0% lower doses are measured.
The radiation dose the personnel are exposed to is directly related with the radiation dose the patient is exposed to, so that the biggest contribution to the personnel dose comes from the scattered radiation from the patient [11]. In the created scenarios, it is determined that the measured radiation doses of the other operation room personnel (assisting doctor, anesthetist and nurse/technician) are lower compared to the fluoroscopy performing doctor. As the position of the fluoroscopy performing doctor is closest to the X-ray tube and the patient that is the source of scattered radiation, he/she is exposed to radiation more than the other medical personnel assigned in the operation room. When the CVP-2 radiation filter is mounted, it collimates the primary radiation bundle and decreases the scattered radiation amount from the patient, so that, compared to the case where the filter is not mounted, the doses of the other operation room personnel are decreased.
In the studies within the literature the occupational radiation doses for extremities and eyes of the personnel performing the operation and the assisting personnel in the interventional operations are determined and it is indicated that the left wrist of the fluoroscopy performing doctor is exposed to highest dose [12]. The dose value at left wrist of the fluoroscopy performing doctor obtained in this study is conforming to the literature. In case of using CVP-2 filter the radiation dose the left wrist is exposed to is decreased by 86.8%. Thus in the case the mentioned filter is used, it is determined that the dose of the left wrist of the personnel where he/she is exposed to the highest dose is also decreased.
According to the assessed TL and ring dosimeter results; in the case when the CVP-2 filter is not mounted, the radiation dose decreasing rates of the led equivalent googles, thyroid protector and led coat used as personal protective equipment are found to be 84.5%, 78.0% and 93.0% respectively. Despite that it is determined that the CVP-2 filter decreases the scattered radiation due to the intensification of the X-rays to the desired area when the filter is attached, as the personnel are still exposed to significant amount of X-rays, when the biological effects of the radiation are considered, even if the CVP-2 radiation filter is used, it is assessed that it cannot replace the personal protective equipment, thus in the mentioned applications, together with the CVP-2 filter, in any case the personnel protective equipment should also be used.
In the examination done with CVP-2 using image quality phantom, it is determined that the contrast resolution is visibly increased at the region the 1st and 2nd images at the quality phantom scale are present, and there is no distinct difference at the other
regions. In this study where a Fluoroscopy Quality Control Phantom is used, the image quality is assessed to be sufficient for diagnostic purposes by a clinician. The images with and without CVP-2 at the radiations made using parameters closest to the clinical imaging parameters are compared to each other and it is seen that no distinct difference is present in image quality. When ion chamber measurements are compared for two images with same image quality, the dose value achieved by image with CVP-2 is determined to be reduced compared to the case without CVP-2 by 71.9% and 68.9% respectively. Thus, it is determined that CVP-2 radiation filter increases contrast resolution without damaging the image quality.
Radiation doses are measured for the case that the CVP-2 filter is not attached between 45-110 kV and for the case that the CVP-2 filter is attached between 70-110 kV. According to the dose change graph for with and without CVP-2 filter, when the dose values measured with ion chamber for cases with and without filter are compared, it is determined that the low energy, unwanted X-rays are absorbed by the CVP-2 filter and thus the patient and the personnel are exposed to less radiation. It is determined that CVP-2 radiation filter decreases the patient skin entry dose, prevents the unwanted X-rays that affect image negatively and thus increases contrast resolution without disrupting image quality, decreased the personnel dose sourced from the scattered radiation from the patient. The mentioned filter, due to the reasons given above, when assessed regarding the radiation protection of the patient and the personnel, it is seen that the filter is a beneficial equipment when the personnel also use the personal protective equipment.
