Radiopharmaceutical Activities Administered for Diagnostic and Therapeutic Procedures in Nuclear Medicine in Argentine: Results of a National Survey

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1 Radiopharmaceutical Activities Administered for Diagnostic and Therapeutic Procedures in Nuclear Medicine in Argentine: Results of a National Survey A. M. Bomben, C. A. Chiliutti Autoridad Regulatoria Nuclear, Av. del Libertador 825 (1429) Buenos Aires, Argentina abomben@sede.arn.gov.ar Abstract. Nuclear medicine in Argentine is carried out at 292 centres. With the purpose of knowing the activity levels of radiopharmaceuticals that were to patients for diagnostic and therapeutic procedures, a national survey was conducted, during 21 and 22. Nuclear medicine physicians in 17 centres voluntarily answered this survey. There were 37 nuclear medicine procedures, chosen among those most frequently pered, that were included in the survey. There were included tests for: bone, brain, lung, thyroid, kidney, liver, gastrointestinal tract and cardiovascular system. The nuclear medicine physicians reported the different radiopharmaceutical to typical adult patients. In this paper are presented the average radiopharmaceutical activity for each of the diagnostic and therapeutic procedures included in the survey and the range and distribution of values. In order to place these data in a frame of reference, these average values were compared to the guidance levels for diagnostic procedures in nuclear medicine. From this comparison it was observed that the in the % of the diagnostic procedures included in the survey were between ± % of the reference values. As a result of this study, it is important to point out the need to continue the gathering of data in a wider scale survey to increase the knowledge about national trends. It is also essential to widely spread the results of this type of surveys, with the purpose of creating awareness of the need for procedures optimization that will result in a better radiation protection of patients. 1. Introduction When nuclear medicine procedures are carried out, the radiopharmaceutical to the patients are very important factors to take into account to optimize the radiation protection of the patient. Whit the purpose of knowing the activity levels of radiopharmaceuticals that were to patients for diagnostic and therapeutic procedures in nuclear medicine in Argentina, a national survey was conducted, during 21 and 22. The survey was prepared and carried out by personnel of the Department of Radioactive Installations and Radiation Source of the Nuclear Regulatory Authority of Argentina. Nuclear medicine in Argentina is carried out at 292 centres, distributed all over the country, mainly concentrated in the provinces capital cities. The survey was distributed during the regulatory inspections and was answered voluntarily by nuclear medicine physicians which were responsible for radiation safety in 17 centres, that means the 37 % of all the nuclear medicine centres of the country. The nuclear medicine centres included in the survey were selected to cover all the country. Seven geographical regions were defined and they are shown in FIG 1. The number of nuclear medicine centres for each region that were included in the survey are shown in Table I. Table I: Centres of nuclear medicine included in the survey, by region Region Number of NM centres in Argentina Number of NM centres included in the survey City of Buenos Aires (Capital Federal) Province of Buenos Aires Northeast 1 7 Northwest 2 7 Pampeana Cuyo 16 4 Patagonia

2 FIG 1. Geographical regions of Argentina To gather ination that reflects the general panorama of the nuclear medicine practice, in the survey were not only included centres where all type of diagnostic tests are carried out but also there were included specialized nuclear medicine centres where only cardiovascular, endocrinological or oncological diagnostic procedures are pered. The nuclear medicine centres included in the survey have different type of equipment. The centres that only have single photon emission computerized tomographs are 51 %, those that only have gamma camera are 27%, and those that only have scintiscanner are 6 %. The centres that have SPECT and gamma camera are 11%, with SPECT and scintiscanner 1% and those with gamma camera and scintiscanner are 4 %. The radiopharmaceutical activity to a patient to conduct a diagnostic or therapeutic procedure in nuclear medicine depends on several characteristics of the patient (physical contexture, age, health state, etc.) and also on the type of medical equipment of the centre. In order to try to reduce the variables, it was asked to the nuclear medicine physicians to report the radiopharmaceutical to typical adult patients. 2. Results In the survey were included 37 nuclear medicine procedures chosen among those most frequently pered. The radionuclides included were, 21 Tl, 67 Ga and 131 I, with their different chemical s. In those diagnostic procedures were included tests for: bone, brain, lung, thyroid, kidney, liver, gastrointestinal tract and cardiovascular system. 2

3 In Tables II to X, are shown the results of the survey. The data corresponding to 32 diagnostic procedures are reported. The other 5 nuclear medicine tests included in the survey have been answered by less than the 1 % of the participants and as the data obtained were not considered representative, the results of these procedures are not presented in this paper. These procedures are: salivary gland with as O 4 -, sentinel lymph nodes detection with nano, red cell survival and red cell volume with 51 Cr-labelled normal erythrocytes and breast with -sestamibi. The ination related to the different diagnostic procedures, the radionuclides and their chemical s as well as the number of nuclear medicine centres that have reported data for each test are shown in the Tables II to X. The range of radiopharmaceutical to patients, the average and the reference levels, for each test are also shown. When the data for a diagnostic test was reported as a range of, instead of reporting a single value, the average activity for that nuclear medicine centre was estimated as the mean between the lowest and highest reported, taking into account the lack of ination on the characteristics of the distribution of the to the patients. In addition, for each diagnostic test, the average value of the radiopharmaceutical activity was calculated as the arithmetic mean considering either the single data reported or the mean values estimated for each centre. To place these data in a frame of reference, these average values were compared to the guidance levels for diagnostic procedures in nuclear medicine mentioned at the Safety Series N 115 [1]. For the tests not included in this publication, the data were compared to values published by UNSCEAR [2], corresponding to countries with heath-care level I, or compared to ARSAC recommended values [3]. From the analysis of the collected data, it was observed that in the % of the diagnostic tests included in the survey the average were within ± % of the reference values considered. The average for thyroid, thyroid uptake tests and thyroid metastases after ablation using 131 I as iodide are significantly below the reference level values. Whereas other average are significantly above of the recommended values, so it is the case of liver with -labelled, lung perfusion with -macroaggregated albumin and the myocardial with -MIBI, all of them by gamma camera. In Figures 2 to 7 are shown the frequency distribution of ranges of for some of the diagnostic procedures included in the survey that have been selected as representative of each group of tests. In spite of the fact that reference levels for therapeutic procedures are not appropriate because the radiopharmaceutical activity to administer is a matter of clinical judgment and must be determined case by case by the nuclear medicine physician responsible for the administration, some therapeutic procedures with unsealed sources were included in the survey just to know the national trends. Taking into account this consideration, it was asked to the participants to report the activity of 131 I, as sodium iodide, to patients for two therapeutic practices. In the case of nuclear medicine therapy for hyperthyroidism, 55 nuclear medicine centres reported data, the average activity was 3 MBq with a range of of MBq. For the thyroid carcinoma therapy, the average activity was 5 GBq, considering the 58 nuclear medicine centres that reported data, and the range of values was 1,95-7,4 GBq. 3. Conclusions As a result of this study, it is important to point out the need to continue the gathering of data in a wider scale survey, including all the nuclear medicine centres of Argentina, to increase the knowledge about national trends. In order to identify tendencies, it appears necessary to gather ination about the type of medical equipment, its age, its calibration and other characteristics of the centres. It is also essential to widely spread the results of this type of surveys (i.e. courses, congresses, professional societies meetings, etc.), with the purpose of creating awareness of the need for procedures optimization, that will result in a better radiation protection of patients. 3

4 4. s 1. International Atomic Energy Agency, International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, Safety Standards, Safety Series No. 115, IAEA, Vienna (1996). 2. United Nations Committee on the Effects of Atomic Radiation, Sources and Effects of Ionizing Radiation, UNSCEAR 2 Report to the General Assembly, with Scientific Annexes. Volume I: Sources, United Nations, New York. 3. National Radiological Protection Board. Administration of Radioactive Substances Advisory Committee, Notes for Guidance on the Clinical Administration of Radiopharmaceuticals and Use of Sealed Radioactive Sources. ARSAC, December Bone (GC) Bone Table II. Diagnostic procedures for bone of nuclear medicine centres Phosph. compound ( ) Phosph. compound ( ) [1] [1] Bone marrow [1] ( ) Phosphonate and phosphate compounds Table III. Diagnostic procedures for brain of nuclear medicine centres Brain (GC) O - 4 / DTPA ( ) Brain O - 4 / DTPA ( ) Cerebral HM-PAO blood flow ( ) ( ) Diethylenetriaminepentaacetic acid ( ) Hexamethyl propylene amine oxime Lung ventilation Lung perfusion (GC) Lung ( ) Macroaggregates ( ) Macroaggregated albumin [1] [1] 92, [1] Table IV. Diagnostic procedures for lung of nuclear medicine centres DTPAaerosol [2] Human albumin ( ) [1] MAA ( ) [1] 4

5 Thyroid Thyroid Thyroid uptake Thyroid metastases (after ablation) Parathyroid Parathyroid ( ) Isonitriles Table V. Diagnostic procedures for thyroid of nuclear medicine centres 131 I I - 59,74-18,5 4,7 17 [2] O , [1] 131 I I - 72,17-7,4 1,9 3,1 [2] 131 I I [1] MIBI( )/ - O 4 21 Tl Tl + chloride 53 7, [3] [1] Table VI. Diagnostic procedures for kidney Number of nuclear medicine centres Range of Renal DTPA 94 18, [1] /renography Renal DMSA( ) [1] ( ) Dimercaptosuccinic acid Liver (GC) Liver Table VII. Diagnostic procedures for liver of nuclear medicine centres [1] [1] Gastrointestinal bleeding Oesophageal Transit and reflux Table VIII. Diagnostic procedures for gastrointestinal tract Number of nuclear medicine centres Range of [1] 54 3, [1] 5

6 (GC) (GC) (GC) Cardiac First pass blood flow studies (lower limbs) First pass blood flow studies (upper limbs) Table IX. Diagnostic procedures for cardiovascular system Number of nuclear medicine centres Range of MIBI ( ) [1] MIBI ( ) [1] 21 Tl Tl + chloride 21 Tl Tl + chloride 27 55, [1] [1] Phosph. compound ( ) [1] Phosph [1] compound ( ) [1] RB (+) MAG3 (#) [1] MAG3 (#) [1] ( ) Isonitriles ( ) Phosphonate and phosphate compounds (+) normal red blood cells (#) Macroaggregated globulin 3 Lymph node Tumour or abscess Table X: miscellaneous of nuclear medicine centres 46 18, [1] 67 Ga Citrate [1] 15 [3] 6

7 % of freque n cy Range of FIG. 2. Frequency distribution of ranges of for bone by SPECT, with -MDP. 5 % of freque n cy 2 1 Range of FIG. 3. Frequency distribution of ranges of for brain by SPECT, with -DTPA. 5 % of freque n cy 2 1 Range of < >7 FIG. 4. Frequency distribution of ranges of for lung by SPECT, with -MAA 7

8 % of freque n cy Range of < FIG. 5. Frequency distribution of ranges of for thyroid, with O 4 -. % of freque n cy Range of < FIG. 6. Frequency distribution of ranges of for renal by SPECT, with -DMSA. 5 % of freque n cy 2 1 Range of < FIG. 7. Frequency distribution of ranges of for myocardial by SPECT, with -MIBI. 8