RESUMEN
BACKGROUND: Quantitative biodistribution, venous blood and excretion data have been obtained following the intravenous bolus injection of AH113804 (18F) Injection in six healthy volunteers (HVs), four males and two females, up to approximately 5 h post-injection. For each subject, key organs and tissues were delineated and analytical fits were made to the image data as functions of time to yield the normalised cumulated activities. These were input to an internal radiation dosimetry calculation based upon the Medical Internal Radiation Dose (MIRD) schema for the Cristy-Eckerman adult male or female phantom. The absorbed doses per unit administered activity to the 24 MIRD-specified target organs were evaluated for an assumed 3.5-h urinary bladder voiding interval using the Organ Level INternal Dose Assessment/Exponential Modelling (OLINDA/EXM) code. The sex-specific absorbed doses were then averaged, and the effective dose per unit administered activity was calculated. RESULTS: Excluding the remaining tissue category, the three source regions with the highest mean initial 18F activity uptake were the liver (18.3%), lung (5.1%) and kidney (4.5%) and the highest mean normalised cumulated activities were the urinary bladder contents and voided urine (1.057 MBq h/MBq), liver (0.129 MBq h/MBq) and kidneys (0.065 MBq h/MBq). The three organs/tissues with the highest mean sex-averaged absorbed doses per unit administered activity were the urinary bladder wall (0.351 mGy/MBq), kidneys (0.052 mGy/MBq) and uterus (0.031 mGy/MBq). CONCLUSIONS: AH113804 (18F) Injection was safe and well tolerated. Although the effective dose, 0.0298 mSv/MBq, is slightly greater than for other common 18F PET imaging radiopharmaceuticals, the biodistribution and radiation dosimetry profile remain favourable for clinical PET imaging.
RESUMEN
With the increasing use of positron emission tomography (PET) for disease staging, follow-up and therapy monitoring in a number of oncological indications there is growing interest in the use of PET and PET-CT for radiation treatment planning. In order to create a strong clinical evidence base for this, it is important to ensure that research data are clinically relevant and of a high quality. Therefore the National Cancer Research Institute PET Research Network make these recommendations to assist investigators in the development of radiotherapy clinical trials involving the use of PET and PET-CT. These recommendations provide an overview of the current literature in this rapidly evolving field, including standards for PET in clinical trials, disease staging, volume delineation, intensity modulated radiotherapy and PET-augmented planning techniques, and are targeted at a general audience. We conclude with specific recommendations for the use of PET in radiotherapy planning in research projects.
Asunto(s)
Neoplasias/radioterapia , Tomografía de Emisión de Positrones/normas , Planificación de la Radioterapia Asistida por Computador/normas , Acreditación , Ensayos Clínicos como Asunto/normas , Instituciones de Salud/normas , Humanos , Movimiento , Imagen Multimodal/métodos , Imagen Multimodal/normas , Neoplasias/diagnóstico por imagen , Neoplasias/patología , Tomografía de Emisión de Positrones/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen/normas , Radioterapia de Intensidad Modulada/normas , Estándares de Referencia , Tomografía Computarizada por Rayos X , Carga TumoralRESUMEN
Patients treated with radioiodine present a radiation hazard and precautions are necessary to limit the radiation dose to family members, nursing staff and members of the public. The precautions advised are usually based on instantaneous dose rates or iodine retention and do not take into account the time spent in close proximity with a patient. We have combined whole-body dose rate measurements taken from 86 thyroid cancer patients after radioiodine administration with published data on nursing and social contact times to calculate the cumulative dose that may be received by an individual in contact with a patient. These dose estimates have been used to calculate restrictions to patients behaviour to limit received doses to less than 1 mSv. We have also measured urinary iodide excretion in 19 patients to estimate the potential risk from the discharge of radioiodide into the domestic drainage system. The dose rate decay was biexponential for patients receiving radioiodine to ablate the thyroid after surgery (the ablation group, A) and monoexponential for these receiving subsequent treatments for residual or recurrent disease (the follow-up group, FU). The faster clearance in the follow-up patients generally resulted in less stringent restrictions than those advised for ablation patients. For typical activities of 1850 MBq for the ablation patients and 3700 MBq or 7400 MBq for the follow-up patients, the following restrictions were advised. Patients could travel in a private car for up to 8h on the day of treatment (for an administered activity of 1850 MBq in group A) or 4 and 2h (for activities of 3700 or 7400 MBq in group FU) respectively. Patients should remain off work for 3 days (1850 MBq/group A) or 2 days (up to 7400 MBq/group FU). Partners should avoid close contact and sleep apart for 16 days (1850 MBq/group A) or 4-5 days (3700 or 7400 MBq/group FU). Contact with children should be restricted according to their age, ranging from 16 days (1850 MBq/group A) or 4-5 days (3700 or 7400 MBq in group FU) for younger children, down to 10 days (1850 MBq/group A) or 4 days (up to 7400 MBq/group FU) for older children. The cumulative dose to nursing staff for the week after treatment was dependent on patient mobility and was estimated at 0.08 mSv for a self-caring patient to 6.3 mSv for a totally helpless patient (1840 MBq/group A). Corresponding doses to nurses looking after patients in group FU were 0.18-12.3 mSv (3700 MBq) or 0.36-24.6 mSv (7400 MBq). Sensible guidelines can be derived to limit the dose received by members of the public and staff who may come into contact with cancer patient treated with radioiodine to less than 1 mSv. The rapid clearance of radioiodine in patients treated on one or more than one occasion means that therapy could be administered at home to selected patients with suitable domestic circumstances. In most cases the restriction times, despite the high administered activities, are less than those for patients treated for thyrotoxicosis. The concentration of radioiodide in domestic drainage systems should not pose a significant risk.