- Email: [email protected]
67. Experimental validation of algorithms used to estimate effective dose during interventional radiology procedures
Abstracts / Physica Medica 56 (2018) 59–132
105
67. Experimental validation of algorithms used to estimate effective dose during interventional radiology procedures P. Negri a, F. Campi a, S. De Crescenzo b, L. Garlati a, O. Tambussi a
68. Scatter ambient equivalent dose from a Cone Beam Computed Tomography for radiation protection purpose N. Romeo a, C. Marino b, E. Bonanno b
a
a
b
Dipartimento di energia, Politecnico di Milano, Milano, Italy S.C Fisica Sanitaria, A.S.S.T G.O.M.M Niguarda, Milano, Italy
Purpose. During interventional radiology procedures the medical staff is exposed to X-rays scattered from the patient, so it is fundamental to wear personal protective equipment. In order to evaluate the effective dose, two dosimeters shall be used: one above the protective apron and one under the protective apron. Several algorithm have been developed to combine the readings of the dosimeters, currently there is no international consensus on which is the best one. In this work, typical interventional radiology procedures have been simulated in order to experimentally verify the accuracy of the algorithms. Material and methods. Eight different irradiation conditions have been simulated in an angiographic room at Niguarda Hospital in Milano. The patient has been reproduced with two different RW3 slabs; the effective dose to personnel has been calculated by TLD inside a Rando-Alderson phantom. Personal dose equivalent (Hp(10)) have been measured by 17 dosimeters, placed on the phantom surface. The phantom has been equipped with a thyroid shield and a protective apron during two irradiations; in the other irradiations, corrections have been applied to dosimeters readings to take into account the effect of protective clothes.
Results. The majority of the algorithms tend to be too conservative, only the one proposed by the NCRP tend to underestimate the effective dose: the algorithms suggested in the ICRP draft seems to be the more reliable. However there are many factors which can affect the accuracy of the algorithms, so it is impossible to achieve a great precision in the evaluation of the effective dose. Conclusions. The algorithms proposed by the ICRP draft shall be used to estimate the effective dose in interventional radiology; in case of risk to exceed the dose limit, it is better to further investigate the irradiation conditions.
https://doi.org/10.1016/j.ejmp.2018.04.077
Azienda Sanitaria Provinciale di Messina, UOC di Radioterapia, Ospedale ‘‘San Vincenzo”, Taormina, Italy b Humanitas Centro Catanese di Oncologia, UOC di Radioterapia, Catania, Italy Purpose. Cone Beam Computed Tomography (CBCT) is a growing modality of complementary radiodiagnostic. It is applied in a wide range of clinical applications like dentistry, interventional radiology in an operating room and radiotherapy. When a new CBCT is to be installed, a preventive structural shielding design is needed in order to evaluate and limit the dose in the adjacent rooms under the national regulation thresholds. Scatter dose at a specific point is an essential input for a radiation protection project. Unfortunately we did not find in literature any systematic data set for scatter dose from a CBCT; values ranging from 2 to 40 lSv/scan at 1 m distance from the centre of the scattering media are reported in the European Commission Document ‘‘Radiation Protection N. 172” [1] and relative to dentistry applications. In the report ICRP 129 [2] the dose to the eye of an operator was reported ranging from 28 to 79 lSv for CBCT hepatic arterial embolisation and biliary tube placement procedures. The purpose of this work was to systematic measure the scatter ambient dose equivalent from a CBCT installed on a linac.
Methods. Primary kilovoltage beam was generated by a CBCT mounted on a VARIAN TRUEBEAM linear accelerator. The target is composed by tungsten (95%) and rhodium (5%); the permanent source filtration was 2.7 mm Alluminium with an additional filtration made of 0.89 mm Titanium. The primary beam irradiated an anthropomorphic CIRS Atom 701-D phantom (adult male phantom at thorax level) during a single complete gantry rotation. Scatter ambient equivalent dose was measured for 4 energy levels (80 KVp , 100 KVp , 125 KVp and 140 KVp ) and for 3 collimations (approximately 7 cm, 16 cm and 23 cm corresponding to a small, medium and large collimation) along the longitudinal axis (axis around which the X-ray source was rotating). Measurements were performed at a height from the floor equal to the isocentric level
105
67. Experimental validation of algorithms used to estimate effective dose during interventional radiology procedures P. Negri a, F. Campi a, S. De Crescenzo b, L. Garlati a, O. Tambussi a
68. Scatter ambient equivalent dose from a Cone Beam Computed Tomography for radiation protection purpose N. Romeo a, C. Marino b, E. Bonanno b
a
a
b
Dipartimento di energia, Politecnico di Milano, Milano, Italy S.C Fisica Sanitaria, A.S.S.T G.O.M.M Niguarda, Milano, Italy
Purpose. During interventional radiology procedures the medical staff is exposed to X-rays scattered from the patient, so it is fundamental to wear personal protective equipment. In order to evaluate the effective dose, two dosimeters shall be used: one above the protective apron and one under the protective apron. Several algorithm have been developed to combine the readings of the dosimeters, currently there is no international consensus on which is the best one. In this work, typical interventional radiology procedures have been simulated in order to experimentally verify the accuracy of the algorithms. Material and methods. Eight different irradiation conditions have been simulated in an angiographic room at Niguarda Hospital in Milano. The patient has been reproduced with two different RW3 slabs; the effective dose to personnel has been calculated by TLD inside a Rando-Alderson phantom. Personal dose equivalent (Hp(10)) have been measured by 17 dosimeters, placed on the phantom surface. The phantom has been equipped with a thyroid shield and a protective apron during two irradiations; in the other irradiations, corrections have been applied to dosimeters readings to take into account the effect of protective clothes.
Results. The majority of the algorithms tend to be too conservative, only the one proposed by the NCRP tend to underestimate the effective dose: the algorithms suggested in the ICRP draft seems to be the more reliable. However there are many factors which can affect the accuracy of the algorithms, so it is impossible to achieve a great precision in the evaluation of the effective dose. Conclusions. The algorithms proposed by the ICRP draft shall be used to estimate the effective dose in interventional radiology; in case of risk to exceed the dose limit, it is better to further investigate the irradiation conditions.
https://doi.org/10.1016/j.ejmp.2018.04.077
Azienda Sanitaria Provinciale di Messina, UOC di Radioterapia, Ospedale ‘‘San Vincenzo”, Taormina, Italy b Humanitas Centro Catanese di Oncologia, UOC di Radioterapia, Catania, Italy Purpose. Cone Beam Computed Tomography (CBCT) is a growing modality of complementary radiodiagnostic. It is applied in a wide range of clinical applications like dentistry, interventional radiology in an operating room and radiotherapy. When a new CBCT is to be installed, a preventive structural shielding design is needed in order to evaluate and limit the dose in the adjacent rooms under the national regulation thresholds. Scatter dose at a specific point is an essential input for a radiation protection project. Unfortunately we did not find in literature any systematic data set for scatter dose from a CBCT; values ranging from 2 to 40 lSv/scan at 1 m distance from the centre of the scattering media are reported in the European Commission Document ‘‘Radiation Protection N. 172” [1] and relative to dentistry applications. In the report ICRP 129 [2] the dose to the eye of an operator was reported ranging from 28 to 79 lSv for CBCT hepatic arterial embolisation and biliary tube placement procedures. The purpose of this work was to systematic measure the scatter ambient dose equivalent from a CBCT installed on a linac.
Methods. Primary kilovoltage beam was generated by a CBCT mounted on a VARIAN TRUEBEAM linear accelerator. The target is composed by tungsten (95%) and rhodium (5%); the permanent source filtration was 2.7 mm Alluminium with an additional filtration made of 0.89 mm Titanium. The primary beam irradiated an anthropomorphic CIRS Atom 701-D phantom (adult male phantom at thorax level) during a single complete gantry rotation. Scatter ambient equivalent dose was measured for 4 energy levels (80 KVp , 100 KVp , 125 KVp and 140 KVp ) and for 3 collimations (approximately 7 cm, 16 cm and 23 cm corresponding to a small, medium and large collimation) along the longitudinal axis (axis around which the X-ray source was rotating). Measurements were performed at a height from the floor equal to the isocentric level