Summary of medicine characteristics - TECHNESCAN DTPA 20.8 MG KIT FOR RADIOPHARMACEUTICAL PREPARATION
1 NAME OF THE MEDICINAL PRODUCT
TechneScan® DTPA 20.8 mg, kit for radiopharmaceutical preparation (Mallinckrodt Medical catalogue number: DRN 4362).
2 QUALITATIVE AND QUANTITATIVE COMPOSITION
Each vial contains 20.8 mg Pentetic acid.
To be reconstituted with sodium pertechnetate (99mTc) for the preparation of the diagnostic agent: Technetium (99mTc) pentetate. The radionuclide is not part of the kit.
For the full list of excipients, see section 6.1.
Kit for radiopharmaceutical preparation.
Off-white to slightly yellow freeze-dried powder for solution for injection.
4.1 Therapeutic indications
This medicinal product is for diagnostic use only.
After reconstitution with sodium pertechnetate (99mTc) solution, the solution of technetium (99mTc) pentetate is indicated for:
a) After intravenous administration for:
Measurement of glomerular filtration rate
Renal perfusion and function and urinary tract studies
Cerebral angioscintigraphy (as an alternative method when computed tomography and/or magnetic resonance imaging are not available).
b) After inhalation of the nebulized technetium (99mTc) pentatate for:
Lung ventilation imaging
c) After oral administration of the technetium (99mTc) pentatate for:
Detection of gastrooesophageal reflux and liquid gastric emptying
study.
4.2 Posology and method of administration
Posology
Adults and the elderly population
The following administered activities are recommended (other activities may be justifiable):
Intravenous route:
– Measurement of glomerular filtration rate from plasma: 7 – 18 MBq.
– Renal scintigraphy: 40 – 400 MBq.
– Cerebral angioscintigraphy: 185 – 740 MBq.
For inhalation:
Lung ventilation imaging:
– 500–1000 MBq deposited in the nebuliser
– 50–100 MBq in the lung.
For oral use:
– Detection of gastrooesophageal reflux and gastric emptying study: 10 – 20 MBq.
– Technetium (99mTc) pentetate is mixed with an appropriate volume (30 to 240
mL) of liquid carrier (e.g. milk).
Renal/ hepatic impairment
Careful consideration of the activity to be administered is required since an increased radiation exposure is possible in these patients (see section 4.4).
Paediatric dose:
The use in children and adolescents has to be considered carefully, based upon clinical needs and assessing the risk/benefit ratio in this patient group. The activities to be administered by intravenous route to children and to adolescents may be calculated according to the recommendations of the European Association of Nuclear Medicine EANM (2016) paediatric dosage card, by using the formula corresponding to the concerned indication and the relevant correction factor corresponding to the body mass of the young patient.
– Administration of technetium (99mTc) pentetate in abnormal renal function:
Administered Activity[MBq] = Baseline Activity x Multiple (with a baseline activity of 14.0)
Table 1
| Body Mass | Multiple | Body Mass | Multiple | Body Mass | Multiple |
| 3 kg | 1 | 22 kg | 5.29 | 42 kg | 9.14 |
| 4 kg | 1.14 | 24 kg | 5.71 | 44 kg | 9.57 |
| 6 kg | 1.71 | 26 kg | 6.14 | 46 kg | 10.00 |
| 8 kg | 2.14 | 28 kg | 6.43 | 48 kg | 10.29 |
| 10 kg | 2.71 | 30 kg | 6.86 | 50 kg | 10.71 |
| 12 kg | 3.14 | 32 kg | 7.29 | 52–54 kg | 11.29 |
| 14 kg | 3.57 | 34 kg | 7.72 | 56–58 kg | 12.00 |
| 16 kg | 4.00 | 36 kg | 8.00 | 60–62 kg | 12.71 |
| 18 kg | 4.43 | 38 kg | 8.43 | 64–66 kg | 13.43 |
| 20 kg | 4.86 | 40 kg | 8.86 | 68 kg | 14.00 |
In very young children (up to 1 year), when technetium (99mTc) pentetate is used for urinary tract examinations, a minimum dose of 20 MBq is necessary to obtain images of sufficient quality.
– Administration of technetium (99mTc) pentetate in normal renal function:
Administered Activity[MBq] = Baseline Activity x Multiple (with a baseline activity of 34.0)
| Table 2 | |||||
| Body Mass | Multiple | Body Mass | Multiple | Body Mass | Multiple |
| 3 kg | 1 | 22 kg | 3.06 | 42 kg | 4.41 |
| 4 kg | 1.12 | 24 kg | 3.18 | 44 kg | 4.53 |
| 6 kg | 1.47 | 26 kg | 3.35 | 46 kg | 4.65 |
| 8 kg | 1.71 | 28 kg | 3.47 | 48 kg | 4.77 |
| 10 kg | 1.94 | 30 kg | 3.65 | 50 kg | 4.88 |
| 12 kg | 2.18 | 32 kg | 3.77 | 52–54 kg | 5.00 |
| 14 kg | 2.35 | 34 kg | 3.88 | 56–58 kg | 5.24 |
| 16 kg | 2.53 | 36 kg | 4.00 | 60–62 kg | 5.47 |
| 18 kg | 2.71 | 38 kg | 4.18 | 64–66 kg | 5.65 |
| 20 kg | 2.88 | 40 kg | 4.29 | 68 kg | 5.77 |
– Lung ventilation imaging: 500 – 1000 MBq deposited in the nebuliser; 10 MBq in the lung.
– Detection of gastroesophageal reflux and liquid gastric emptying study: 10 – 20 MBq. Administered activity of the radiopharmaceutical and the volume to be fed to the patient should be based on patient factors such as age, body weight, and the usual feeding volume. Administered activity for children should be as low as reasonably achievable for diagnostic image quality.
Method of administration
For intravenous, inhalation and oral administration.
For multidose use.
This medicinal product should be reconstituted before administration to the patient.
For instructions on reconstitution and radiolabelling of the medicinal product before administration, see section 12.
For patient preparation, see section 4.4.
Image acquisition
– Renal perfusion imaging is obtained by dynamic acquisitions immediately after injection up to 1 minute. The optimal static imaging time is 1hour post injection. In case of captopril (ACE inhibitor) renography, captopril is given intravenously before technetium (99mTc) pentetate administration. Individual kidney function and urinary outflow imaging are obtained by dynamic acquisitions performed after injection. If one or both kidneys have not emptied satisfactorily during the first 20 minutes, a furosemide challenge is performed, and the dynamic acquisition should continue for a further 15-minute after the diuretic. Static images may be acquired 1 hour after injection.
– For cerebral examinations, dynamic acquisitions should begin immediately after injection. Static images are obtained 1 hour and, if necessary, several hours after injection.
– For lung ventilation imaging: images of the lungs are obtained during 180 min.
Dynamic images of oesophagus are obtained during the first minutes after administration followed by continuous imaging for 60 minutes for evaluation of gastroesophageal reflux. Gastric emptying at 60 minutes and at 2 or 3 hours after completion of feeding is calculated.
4.3 Contraindications
Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.
4.4 Special warnings and precautions for use
Potential for hypersensitivity or anaphylactic reactions:
If hypersensitivity or anaphylactic reactions occur, the administration of the medicinal product must be discontinued immediately and intravenous treatment initiated, if necessary. To enable immediate action in emergencies, the necessary medicinal products and equipment such as endotracheal tube and ventilator must be immediately available.
Individual benefit/risk justification
For each patient, the radiation exposure must be justifiable by the likely benefit. The activity administrated should in every case be as low as reasonably achievable to obtain the required diagnostic information.
Renal/ hepatic impairment
Careful consideration of the benefit risk ratio in these patients is required since an increased radiation exposure is possible.
Paediatric population
For information on use in the paediatric population, see section 4.2.
Careful consideration of the indication is required since the effective dose per MBq is higher than in adults (see section 11).
Patient preparation
The patient should be well-hydrated before the start of the examination and urged to void as often as possible during the first hours after the examination in order to reduce radiation.
Special warnings
TechneScan DTPA injection solution should not be administered in the subarachnoid space and should never be used for scintigraphy of the cerebrospinal flow.
Precautions with respect to environmental hazard see section 6.6.
Depending on the time when you administer the injection, the content of sodium given to the patient may in some cases be greater than 1mmol. This should be taken into account in patients on low sodium diet.
4.5 Interaction with other medicinal products and other forms of interaction
Many drugs may affect the function of tested organ and modify the uptake of technetium (99mTc) pentetate:
Diagnostic use of captopril
Dynamic renal scanning performed under control conditions and again one hour after oral administration of captopril (25–50 mg) may reveal haemodynamic changes in a kidney affected by renal artery stenosis. The blood pressure should be carefully monitored as patients with vascular disease are at risk of significant hypotension and renal impairment.
Diagnostic use of furosemide
The administration of intravenous frusemide during dynamic renal scanning increase elimination of technetium (99mTc) pentetate (DTPA) which may help to distinguish whether true obstruction exists in a dilated renal tract.
Cerebral angioscintigraphy
Psychotropic drugs increase blood flow in the territory of the external carotid artery. This may lead to the rapid uptake of tracer in the nasopharyngeal area during the arterial and capillary phases (hot nose phenomenon).
4.6 Fertility, pregnancy and lactation
Woman of childbearing potential
When it is necessary to administer radioactive medicinal products to women of childbearing potential, information should always be sought about pregnancy. Any woman who has missed a period should be assumed to be pregnant until proven otherwise. If in doubt about her potential pregnancy (if the woman has missed a period, if the period is very irregular, etc.), alternative techniques not using ionising radiation (if there are any) should be offered to the patient.
Pregnancy
Radionuclide procedures carried out on pregnant women also involve radiation doses to the foetus. Only imperative investigations should be carried out during pregnancy, when the likely benefit exceeds the risk incurred by mother and foetus.
Breast-feeding
Before administering a radioactive medicinal product to a mother who is breast-feeding consideration should be given as to whether the investigation could be reasonably delayed until the mother has ceased breast-feeding and as to whether the most appropriate choice of radiopharmaceutical has been made, bearing in mind the secretion of activity in breast milk. If the administration is considered necessary, the breast-feeding should be interrupted for 12 hours and the expressed feeds discarded.
Fertility
No study on fertility has been performed.
4.7 Effects on ability to drive and use machines
Technetium (99mTc) pentetate has no or negligible influence on the ability to drive and use machines.
4.8 Undesirable effects
The adverse events are presented in the table below by system organ classes and with a not known frequency (cannot be estimated from the available data).
| System Organ Class | Symptom | Frequency |
| Nervous system disorders | Dizziness | Not known |
| Respiratory, thoracic and mediastinal disorders | Dyspnoea | Not known |
| Skin and subcutaneous tissue disorders | Urticaria, pruritus | Not known |
| Vascular disorders | Hypotension, Flushing | Not known |
Exposure to ionising radiation is linked with cancer induction and a potential for development of hereditary defects. As the effective dose is 3.6 mSv when the maximal recommended activity of 740 MBq is administered these adverse events are expected to occur with a low probability.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme
Website: https://yellowcard.mhra.gov.uk/ or search for MHRA Yellow Card in the Google Play or Apple App Store.
4.9 Overdose
4.9 OverdoseIn the event of the administration of a radiation overdose with technetium (99mTc) pentetate the absorbed dose to the patient should be reduced where possible by increasing the elimination of the radionuclide from the body by forced diuresis and frequent bladder voiding. It might be helpful to estimate the effective dose that was applied.
5 PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Diagnostic radiopharmaceuticals for the renal and respiratory systems, Technetium (99mTc) compounds.
ATC code: V09C A01; V09E A01
Mechanism of action:
Technetium(99mTc) pentetate, like inulin, circulates in blood with negligible binding to plasma proteins. It is filtered through the glomerular membrane and undergoes no tubular secretion or reabsorption It does not cross the normal blood-brain barrier (BBB).
Technetium (99mTc) pentetate is aerosolised from a water solution with a particle size of 1.2 – 2 micrometer. After inhalation aerosol droplets are distributed and deposited within airways and alveoli depending on their aerodynamic properties, particularly their mass median aerodynamic diameter.
Following oral administration, technetium (99mTc) pentetate does not pass through the digestive barrier (non-absorbable). Mixed with the meal, technetium (99mTc) pentetate follows digestive transit.
Pharmacodynamic effects:
At the concentrations and activities such as those used for diagnosis, 99mTc pentetate does not appear to have any pharmacodynamic activity.
5.2 Pharmacokinetic properties
Distribution
Following intravenous injection, technetium (99mTc) pentetate rapidly distributes throughout the extracellular fluid. Less than 5% of the injected dose is bound to the plasma proteins. There is also a negligible binding of technetium (99mTc) pentetate to red blood cells. Technetium (99mTc) pentetate does not cross the normal blood-brain barrier but diffuse weakly in breast milk.
In patients exhibiting oedema or ascites, distribution of the radioisotope in the extracellular spay may be modified.
In lung ventilation studies, after inhalation, technetium (99mTc) pentetate diffuses rapidly from the pulmonary alveoles towards the vascular space where it is diluted. Many factors are likely to modify the permeability of the pulmonary epithelium like cigarette smoking.
Following oral administration, technetium (99mTc) pentetate does not pass through the digestive barrier.
Elimination
Plasma clearance is multi-exponential with an extremely fast component. The complex remains stable in vivo, more than 98% of urine radioactivity is in the form of a chelate.
Approximately 90% of the injected dose is eliminated in the urine within the first 24 hours mainly by glomerular filtration. No retention of the compound has been demonstrated in the kidneys.
Half-life
The physical half-life of technetium (99mTc) is 6.01 hours.
The half-life of technetium (99mTc) pentetate in the lungs is slightly less than 1 hour.
Renal/Hepatic impairment
Plasma clearance may be delayed in patients with renal disease.
The pharmacokinetics in patients with hepatic impairment has not been characterised.
5.3 Preclinical safety data
5.3 Preclinical safety dataThis agent is not intended for regular or continuous administration. Repeated intravenous administration of CaNa3DTPA to rabbits and dogs for 14 days of doses that were 100 and 1000 times (respectively) the normal dose for human, produced no evidence of toxicity. The minimum dose of CaDTPA causing abortion and fetal death in mice was approximately 3600 times the dose of CaNa3DTPA that is proposed for diagnosis in women. Mutagenicity studies and long-term carcinogenicity studies have not been carried out.
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Gentisic acid
Stannous chloride dihydrate
Calcium chloride dihydrate
Sodium hydroxide
Hydrochloric acid (for pH adjustment)
6.2 Incompatibilities
This medicinal product must not be mixed with other medicinal products apart from those mentioned in section 12.
6.3 Shelf life
1 year when stored below 25°C.
The expiry date is stated on the label of each vial and on the carton box.
After radiolabelling: 8 hours when stored below 25°C.
6.4 Special Precautions for Storage
Keep the vials in the outer carton.
For storage conditions after radiolabelling of the medicinal product, see section 6.3.
Storage of radiopharmaceuticals should be in accordance with the national regulations on radioactive materials.
6.5 Nature and contents of container
Carton box containing 5 glass vials of 10 mL (Type 1 Ph Eur) closed with a bromobutyl rubber lyophilisation stopper sealed with an aluminium cap.
6.6 Special precautions for disposal and other handling
6.6 Special precautions for disposal and other handlingGeneral warning
Radiopharmaceuticals should be received, used and administered only by authorised persons in designated clinical settings. Their receipt, storage, use, transfer and disposal are subject to the regulations and/or appropriate licences of the competent official organisation.
Radiopharmaceuticals should be prepared in a manner which satisfies both radiation safety and pharmaceutical quality requirements. Appropriate aseptic precautions should be taken.
Contents of the kit are intended only for use in the preparation of technetium (99mTc) pentetate and are not to be administered directly to the patient without first undergoing the preparative procedure.
For instructions on reconstitution of the medicinal product before administration, see section 12.
If at any time in the preparation of this product the integrity of this vial is compromised it should not be used.
Administration procedures should be carried out in a way to minimise risk of contamination of the medicinal product and irradiation of the operators. Adequate shielding is mandatory.
The content of the kit before reconstitution is not radioactive. However, after sodium pertechnetate (99mTc) is added, adequate shielding of the final preparation must be maintained.
The administration of radiopharmaceuticals creates risks for other persons from external radiation or contamination from spills of urine, vomiting, etc. Radiation protection precautions in accordance with national regulations must therefore be taken.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
7 MARKETING AUTHORISATION HOLDER
Mallinckrodt Medical B.V.
Westerduinweg 3
1755 LE Petten
Netherlands
8 MARKETING AUTHORISATION NUMBER(S)
PL 12288/0011
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THEAUTHORISATION
30/01/2007
10 DATE OF REVISION OF THE TEXT
07/11/2021
11 DOSIMETRY
Technetium (99mTc) is produced by means of a (99Mo/99mTc) generator and decays with the emission of gamma radiation with a mean energy of 140 keV and a half-life of 6.02 hours to (99Tc) technetium, which, in view of its long half-life of 2.13 × 105 years, can be considered as quasi stable.
The data listed below are from ICRP 128 and are calculated according to the following assumptions:
Intravenous administration of technetium (99mTc) pentetate gives rise to an initial distribution in the extracellular fluid. Following this initial distribution phase, the substance is excreted exclusively by the renal system. In case of normal renal function, total body retention is described by a bi-exponential function with component half-times of 100 min (0.99) and 7 days (0.01). The fraction excreted by the kidneys is 1.0 (1.0), and the renal transit time is 5 min. In case of abnormal renal function, it is assumed that the retention half-time of the major component is 1000 min, and the renal transit time is increased to 20 min.
According to the provisions of the International Commission of Radiological Protection (ICRP 128), the radiation doses absorbed by the patient after intravenous injection are the following:
| Absorbed dose per unit activity administered (mGy/MBq) | |||||
| Normal renal function | |||||
| Organ | Adult | 15 years | 10 years | 5 years | 1 year |
| Adrenals | 0.0014 | 0.0018 | 0.0027 | 0.004 | 0.0072 |
| Bone surfaces | 0.0024 | 0.0029 | 0.0043 | 0.0061 | 0.010 |
| Brain | 0.00086 | 0.0011 | 0.0017 | 0.0028 | 0.0049 |
| Breast | 0.00072 | 0.00092 | 0.0013 | 0.0022 | 0.0041 |
| Gallbladder | 0.0015 | 0.0021 | 0.0038 | 0.005 | 0.0061 |
| Gastrointestinal tract | |||||
| Stomach wall | 0.0013 | 0.0017 | 0.0028 | 0.0040 | 0.0068 |
| Small intestine wall | 0.0025 | 0.0031 | 0.0049 | 0.0070 | 0.010 |
| Colon wall | 0.0031 | 0.0039 | 0.0060 | 0.0081 | 0.011 |
| Upper large intestine wall | 0.0021 | 0.0028 | 0.0043 | 0.0065 | 0.0092 |
| Lower large intestine wall | 0.0043 | 0.0054 | 0.0082 | 0.010 | 0.013 |
| Heart wall | 0.0012 | 0.0015 | 0.0022 | 0.0033 | 0.0059 |
| Kidneys | 0.0044 | 0.0053 | 0.0075 | 0.011 | 0.018 |
| Liver | 0.0012 | 0.0016 | 0.0025 | 0.0038 | 0.0064 |
| Lungs | 0.001 | 0.0013 | 0.002 | 0.003 | 0.0055 |
| Muscles | 0.0016 | 0.002 | 0.003 | 0.0043 | 0.0068 |
| Ovaries | 0.0042 | 0.0053 | 0.0077 | 0.01 | 0.013 |
| Pancreas | 0.0014 | 0.0018 | 0.0028 | 0.0043 | 0.0074 |
| Red marrow | 0.0015 | 0.0018 | 0.0027 | 0.0037 | 0.0057 |
| Skin | 0.00087 | 0.001 | 0.0017 | 0.0026 | 0.0044 |
| Spleen | 0.0013 | 0.0016 | 0.0026 | 0.0039 | 0.0068 |
| Testes | 0.0029 | 0.004 | 0.0068 | 0.0094 | 0.013 |
| Thymus | 0.001 | 0.0013 | 0.0019 | 0.0030 | 0.0054 |
| Thyroid | 0.001 | 0.0013 | 0.0021 | 0.0033 | 0.006 |
| Urinary bladder wall | 0.062 | 0.078 | 0.11 | 0.15 | 0.17 |
| Uterus | 0.0079 | 0.0096 | 0.015 | 0.018 | 0.022 |
| Remaining organs | 0.0017 | 0.0021 | 0.0030 | 0.0042 | 0.0066 |
| Effective dose (mSv/MBq) | |||||
| 0.0049 | 0.0063 | 0.0094 | 0.012 | 0.016 | |
The effective dose resulting from the administration of a maximal recommended activity of 740 MBq for an adult weighing 70 kg is about 3.6 mSv.
For an administered activity of 740 MBq the typical radiation dose to the target organ (kidneys) is
3.3 mGy and the typical radiation dose to the critical organ (urinary bladder wall) is 46 mGy.
| Absorbed dose per unit activity administered (mGy/MBq) | |||||
| Abnormal renal function | |||||
| Organ | Adult | 15 years | 10 years | 5 years | 1 year |
| Adrenals | 0.0041 | 0.0051 | 0.0076 | 0.011 | 0.021 |
| Bone surfaces | 0.006 | 0.0071 | 0.011 | 0.015 | 0.028 |
| Brain | 0.0028 | 0.0035 | 0.0057 | 0.0091 | 0.016 |
| Breast | 0.0023 | 0.003 | 0.0042 | 0.0068 | 0.013 |
| Gallbladder wall | 0.0042 | 0.0057 | 0.0092 | 0.013 | 0.016 |
| Gastrointestinal tract | |||||
| Stomach wall | 0.0038 | 0.005 | 0.0079 | 0.011 | 0.019 |
| Small intestine wall | 0.0045 | 0.0056 | 0.0085 | 0.013 | 0.022 |
| Colon wall | 0.0045 | 0.0058 | 0.0087 | 0.013 | 0.022 |
| Upper large intestine wall | 0.0043 | 0.0056 | 0.0081 | 0.013 | 0.021 |
| Lower large intestine wall | 0.0049 | 0.0061 | 0.0095 | 0.013 | 0.023 |
| Heart wall | 0.0037 | 0.0047 | 0.007 | 0.01 | 0.018 |
| Kidneys | 0.0077 | 0.0092 | 0.013 | 0.019 | 0.032 |
| Liver | 0.0037 | 0.0046 | 0.0071 | 0.011 | 0.019 |
| Lungs | 0.0033 | 0.0042 | 0.0062 | 0.0095 | 0.017 |
| Muscles | 0.0032 | 0.004 | 0.0061 | 0.0091 | 0.017 |
| Ovaries | 0.005 | 0.0062 | 0.0092 | 0.014 | 0.023 |
| Pancreas | 0.0043 | 0.0053 | 0.008 | 0.012 | 0.021 |
| Red marrow | 0.0034 | 0.0042 | 0.0064 | 0.0093 | 0.016 |
| Skin | 0.0022 | 0.0026 | 0.0042 | 0.0067 | 0.012 |
| Spleen | 0.0038 | 0.0047 | 0.0073 | 0.011 | 0.019 |
| Testes | 0.0035 | 0.0045 | 0.0069 | 0.01 | 0.018 |
| Thymus | 0.0033 | 0.0042 | 0.0062 | 0.0096 | 0.017 |
| Thyroid | 0.0034 | 0.0042 | 0.0067 | 0.011 | 0.019 |
| Urinary bladder wall | 0.021 | 0.027 | 0.039 | 0.05 | 0.066 |
| Uterus | 0.0061 | 0.0074 | 0.011 | 0.016 | 0.025 |
| Remaining organs | 0.0033 | 0.0041 | 0.0063 | 0.0097 | 0.017 |
| Effective dose (mSv/MBq) | |||||
| 0.0046 | 0.0058 | 0.0087 | 0.013 | 0.021 | |
The physical half-life of 99mTc is 6.01 h.
The urinary bladder wall contributes up to 57% of the effective dose.
The data listed below are from ICRP 53 and are calculated according to the following assumptions:
Inhalation of technetium (99mTc) pentetate
Inhalation of aerosol consisting of particles smaller than 2–3 micrometer in diameter results in deposition mainly in the alveoli. Particles are rapidly cleared from the lungs via the blood stream. The biological half-life of technetium (99mTc) pentetate in the lungs is 60–80 minutes in normal non-smokers; it is shortened in smokers and in most patients with lung disease. A value of 60 min is adopted below. Substance reaching the blood is eliminated according to the model for intravenously administered technetium (99mTc) pentetate.
According to ICRP 53 the radiation doses given to a man on administration by aerosol technetium (99mTc) pentetate are:
| Absorbed dose per unit activity administered (mGy/MBq | ) | ||||
| Organ | Adult | 15 years | 10 years | 5 years | 1 year |
| Adrenals | 0.0021 | 0.0029 | 0.0044 | 0.0067 | 0.012 |
| Bladder wall | 0.047 | 0.058 | 0.084 | 0.12 | 0.23 |
| Bone surfaces | 0.0019 | 0.0024 | 0.0035 | 0.0053 | 0.0098 |
| Breast | 0.0019 | 0.0019 | 0.0033 | 0.0048 | 0.0078 |
| Gastrointestinal tract | |||||
| Stomach wall | 0.0017 | 0.0022 | 0.0035 | 0.0051 | 0.0089 |
| Small intestine wall | 0.0021 | 0.0026 | 0.0041 | 0.0063 | 0.011 |
| Upper large intestine wall | 0.0019 | 0.0024 | 0.0038 | 0.0061 | 0.01 |
| Lower large intestine wall | 0.0032 | 0.0042 | 0.0063 | 0.0088 | 0.015 |
| Kidneys | 0.0041 | 0.0051 | 0.0072 | 0.011 | 0.019 |
| Liver | 0.0019 | 0.0025 | 0.0037 | 0.0055 | 0.0097 |
| Lungs | 0.017 | 0.026 | 0.036 | 0.054 | 0.1 |
| Ovaries | 0.0033 | 0.0041 | 0.0061 | 0.0089 | 0.015 |
| Pancreas | 0.0021 | 0.0026 | 0.004 | 0.0061 | 0.011 |
| Red marrow | 0.0027 | 0.0034 | 0.0047 | 0.0062 | 0.0096 |
| Spleen | 0.0019 | 0.0024 | 0.0036 | 0.0056 | 0.0099 |
| Testes | 0.0021 | 0.0031 | 0.0052 | 0.0079 | 0.015 |
| Thyroid | 0.00099 | 0.0017 | 0.0027 | 0.0044 | 0.0078 |
| Uterus | 0.0059 | 0.0072 | 0.011 | 0.016 | 0.027 |
| Other tissues | 0.0018 | 0.0022 | 0.0032 | 0.0049 | 0.0086 |
| Effective dose equivalent (mSv/MBq) | |||||
| 0.007 | 0.0091 | 0.013 | 0.02 | 0.036 | |
The effective dose equivalent resulting from the inhalation of a maximal recommended activity of
100 MBq for an adult weighing 70 kg is about 0.7 mSv.
For an inhalated activity of 100 MBq the typical radiation dose to the target organ (lungs) is 1.7 mGy and the typical radiation dose to the critical organ (urinary bladder wall) is 4.7 mGy.
The data listed below are from ICRP 53 and are calculated according to the following assumptions:
Oral administration of technetium (99mTc) pentetate
Technetium (99mTc) pentetate is considered as non-absorbable marker in studies of the gastrointestinal tract. The gastric residence time is fixed to 33 min for fluids.
The radiation doses given to a man on oral administration of technetium(99mTc) pentetate are the following:
| Absorbed dose per unit activity administered (mGy/MBq | 1) | ||||
| Organ | Adult | 15 years | 10 years | 5 years | 1 year |
| Adrenals | 0.0021 | 0.0033 | 0.0054 | 0.0089 | 0.015 |
| Bladder wall | 0.007 | 0.009 | 0.014 | 0.022 | 0.035 |
| Bone surfaces | 0.0028 | 0.0035 | 0.005 | 0.0074 | 0.014 |
| Breast | 0.00042 | 0.00042 | 0.00092 | 0.0019 | 0.0038 |
| Gastrointestinal tract | |||||
| Stomach wall | 0.024 | 0.03 | 0.042 | 0.068 | 0.13 |
| Small intestine wall | 0.072 | 0.091 | 0.15 | 0.23 | 0.40 |
| Upper large intestine wall | 0.13 | 0.16 | 0.26 | 0.41 | 0.77 |
| Lower large intestine wall | 0.088 | 0.11 | 0.18 | 0.29 | 0.55 |
| Kidneys | 0.0057 | 0.0067 | 0.01 | 0.015 | 0.023 |
| Liver | 0.004 | 0.0049 | 0.0093 | 0.016 | 0.027 |
| Lungs | 0.00067 | 0.00091 | 0.0016 | 0.0029 | 0.0057 |
| Ovaries | 0.026 | 0.032 | 0.047 | 0.069 | 0.11 |
| Pancreas | 0.0065 | 0.0079 | 0.012 | 0.018 | 0.031 |
| Red marrow | 0.0089 | 0.01 | 0.013 | 0.015 | 0.018 |
| Spleen | 0.0042 | 0.005 | 0.0078 | 0.012 | 0.02 |
| Testes | 0.0013 | 0.0020 | 0.0038 | 0.0064 | 0.012 |
| Thyroid | 0.00004 | 0.000048 | 0.00015 | 0.00038 | 0.0011 |
| Uterus | 0.015 | 0.020 | 0.031 | 0.048 | 0.077 |
| Other tissues | 0.0034 | 0.004 | 0.0059 | 0.0089 | 0.015 |
| Effective dose equivalent (mSv/MBq) | |||||
| 0.024 | 0.029 | 0.047 | 0.073 | 0.13 | |
The effective dose equivalent resulting from the oral administration of a maximal recommended activity of 20 MBq for an adult weighing 70 kg is about 0.38 mSv.
For an administered activity of 20 MBq the typical radiation dose to the target organ (stomach) is 0.44 mGy and the typical radiation doses to the critical organs (upper large intestine and lower large intestine) are 2.4 and 1.66 mGy, respectively.