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Radioiodine Therapy of Hyperthyroidism - Simplified patient-specific absorbed dose planning

Jönsson, Helene LU (2003)
Abstract (Swedish)
Popular Abstract in Swedish

Radiojodbehandling av sköldkörteln är den vanligaste radiofarmakaterapin. För att beräkna aktiviteten 131I som krävs för att ge en viss stråldos till sköldkörteln behöver sköldkörtelns massa och den individuella biokinetiken bestämmas. Biokinetiken består vanligtvis av det individuella upptaget av jodid och den biologiska halveringstiden av jod i sköldkörteln. Den biologiska halveringstiden och därmed den effektiva halveringstiden bestäms utifrån flera upptagsmätningar där den första mätningen vanligtvis görs 24 timmar efter intag av en testaktivitet, d.v.s. undersökningsdos. Många sjukhus anser att det tar för mycket tid eftersom åtminstone tre sjukhusbesök av patienten krävs (administrering av... (More)
Popular Abstract in Swedish

Radiojodbehandling av sköldkörteln är den vanligaste radiofarmakaterapin. För att beräkna aktiviteten 131I som krävs för att ge en viss stråldos till sköldkörteln behöver sköldkörtelns massa och den individuella biokinetiken bestämmas. Biokinetiken består vanligtvis av det individuella upptaget av jodid och den biologiska halveringstiden av jod i sköldkörteln. Den biologiska halveringstiden och därmed den effektiva halveringstiden bestäms utifrån flera upptagsmätningar där den första mätningen vanligtvis görs 24 timmar efter intag av en testaktivitet, d.v.s. undersökningsdos. Många sjukhus anser att det tar för mycket tid eftersom åtminstone tre sjukhusbesök av patienten krävs (administrering av undersökningsaktivitet, första upptagsmätning, andra upptagsmätning plus behandling). Istället använder sjukhus ett fast värde på den effektiva halveringstiden eller administrerar en standardaktivitet där bara två sjukhusbesök krävs av patienten. Ingen av dessa metoder beräknar stråldosen till sköldkörteln för den individuella patienten. I det här arbetet föreslås en förenklad patientspecifik metod för att behandla hypertyroidism, baserat på en enda upptagsmätning. Beräkningen ger samma resultat som om det individuella upptaget och den individuella effektiva halveringstiden använts. Denna förenklade metod kräver precis som metoder med fast värde på den effektiva halveringstiden eller en standardaktivitet också bara två besök till sjukhuset. Beräkningen baseras på en linjär relation mellan en sen upptagsmätning 4-7 dagar efter undersökningsdosen och produkten av det extrapolerade initiala upptaget och den effektiva halveringstiden. Behandlingar som inte tar hänsyn till den individuella biokinetiken i sköldkörteln resulterar i en distribution av stråldosen till sköldkörteln, med ett intervall på -50 % till +160 % jämfört med en metod som beräknar stråldosen till sköldkörteln för varje individuell patient. Behandling med en standardaktivitet på 370 MBq resulterar i genomsnitt i 250 % högre aktivitet till patienten, med ett intervall på -30 % till +770 %, jämfört med om stråldosen till sköldkörteln beräknats. Den absorberade dosen till andra organ än sköldkörteln påverkas också. Dessa doser bör beaktas när riskerna med sena strålskador uppskattas. Detta är viktigt eftersom allt fler yngre patienter behandlas med radiojod. Om alla sjukhus i Sverige tar hänsyn till den individuella biokinetiken vid radiojodbehandling kommer den totala administrerade aktiviteten 131I att minska med 10 % (100 GBq) motsvarande en årlig kollektiv effektiv dos på 17 manSv, sköldkörteln ej medräknad. Sjutton olika metoder för att bestämma den aktiviteten 131I som ska ges till patienten används vid de 23 svenska sjukhus som utför radiojodbehandling. Bara nio sjukhus beräknar administrerad aktivitet 131I genom att använda den individuella biokinetiken. Mer ansträngningar behöver göras för att hänsyn till den individuella biokinetiken ska tas när den administrerade aktiviteten 131I ska beräknas, samtidigt kommer onödig stråldos till den individuella patienten och dennes familj och allmänheten att minska. (Less)
Abstract
Radioiodine therapy of hyperthyroidism is the most frequently performed radiopharmaceutical therapy. To calculate the activity of 131-I to be administered for giving a certain absorbed dose to the thyroid, the mass of the thyroid and the individual biokinetic data, normally in the form of uptake and biologic half-time, have to be determined. The biologic half-time is estimated from several uptake measurements and the first one is usually made 24 hours after the intake of the test activity. However, many hospitals consider it time-consuming since at least three visits of the patient to the hospital are required (administration of test activity, first uptake measurement, second uptake measurement plus treatment). Instead, many hospitals use... (More)
Radioiodine therapy of hyperthyroidism is the most frequently performed radiopharmaceutical therapy. To calculate the activity of 131-I to be administered for giving a certain absorbed dose to the thyroid, the mass of the thyroid and the individual biokinetic data, normally in the form of uptake and biologic half-time, have to be determined. The biologic half-time is estimated from several uptake measurements and the first one is usually made 24 hours after the intake of the test activity. However, many hospitals consider it time-consuming since at least three visits of the patient to the hospital are required (administration of test activity, first uptake measurement, second uptake measurement plus treatment). Instead, many hospitals use a fixed effective half-time or even a fixed administered activity, only requiring two visits. However, none of these methods considers the absorbed dose to the thyroid of the individual patient. In this work a simplified patient-specific method for treating hyperthyroidism is proposed, based on one single uptake measurement, thus requiring only two visits to the hospital. The calculation is as accurate as using the individual biokinetic data. The simplified method is as patient-convenient and time-effective as using a fixed effective half-time or a fixed administered activity. The simplified method is based upon a linear relation between the late uptake measurement 4-7 days after intake of the test activity and the product of the extrapolated initial uptake and the effective half-time. Treatments not considering individual biokinetics in the thyroid result in a distribution of administered absorbed dose to the thyroid, with a range of -50 % to +160 % compared to a protocol calculating the absorbed dose to the thyroid of the individual patient. Treatments with a fixed administered activity of 370 MBq will in general administer 250 % higher activity to the patient, with a range of -30 % to +770 %. The absorbed dose to other organs than the thyroid is also influenced. These doses should also be considered in estimating the risk of late radiation effects in the patients. This is becoming more important as an increasing number of younger patients are treated with radioiodine. If all Swedish hospitals considered the individual biokinetic data the total administrated activity of 131-I would decrease by 10 % (100 GBq) corresponding to a yearly collective effective dose of 17 manSv, thyroid excluded. Seventeen different methods to determine the administered activity of 131-I are in use in 23 Swedish hospitals. Only nine hospitals calculate the administered activity of 131-I using individual biokinetic data. More effort should be done to consider the individual biokinetic data when calculating the administered activity of 131-I and thus decrease unnecessary radiation dose to individual patients, their families and the public. (Less)
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author
opponent
  • Professor Jacobsson, Lars, Department of Radiation Physics, Göteborg University
organization
publishing date
type
Thesis
publication status
published
subject
keywords
radiobiologi, Radiofarmaceutisk teknik, Radiopharmaceutical technology, absorbed dose. optimise, hyperthyroidism, therapy, 131-I, radioiodine, Nukleärmedicin, radiobiology, Nuclear medicine
pages
105 pages
publisher
Helene Jönsson, Swedish Radiation Protection Authority, SE-171 16 Stockholm, Sweden,
defense location
Wallenberglab. föreläsningssal Medelhavet,Universitetssjukhuset MAS, Malmö
defense date
2003-10-30 10:15
ISBN
91-628-5753-3
language
English
LU publication?
yes
id
a463b007-54c4-4edc-a2bd-0d580a951ac2 (old id 466293)
date added to LUP
2007-09-27 10:01:59
date last changed
2016-09-19 08:45:07
@misc{a463b007-54c4-4edc-a2bd-0d580a951ac2,
  abstract     = {Radioiodine therapy of hyperthyroidism is the most frequently performed radiopharmaceutical therapy. To calculate the activity of 131-I to be administered for giving a certain absorbed dose to the thyroid, the mass of the thyroid and the individual biokinetic data, normally in the form of uptake and biologic half-time, have to be determined. The biologic half-time is estimated from several uptake measurements and the first one is usually made 24 hours after the intake of the test activity. However, many hospitals consider it time-consuming since at least three visits of the patient to the hospital are required (administration of test activity, first uptake measurement, second uptake measurement plus treatment). Instead, many hospitals use a fixed effective half-time or even a fixed administered activity, only requiring two visits. However, none of these methods considers the absorbed dose to the thyroid of the individual patient. In this work a simplified patient-specific method for treating hyperthyroidism is proposed, based on one single uptake measurement, thus requiring only two visits to the hospital. The calculation is as accurate as using the individual biokinetic data. The simplified method is as patient-convenient and time-effective as using a fixed effective half-time or a fixed administered activity. The simplified method is based upon a linear relation between the late uptake measurement 4-7 days after intake of the test activity and the product of the extrapolated initial uptake and the effective half-time. Treatments not considering individual biokinetics in the thyroid result in a distribution of administered absorbed dose to the thyroid, with a range of -50 % to +160 % compared to a protocol calculating the absorbed dose to the thyroid of the individual patient. Treatments with a fixed administered activity of 370 MBq will in general administer 250 % higher activity to the patient, with a range of -30 % to +770 %. The absorbed dose to other organs than the thyroid is also influenced. These doses should also be considered in estimating the risk of late radiation effects in the patients. This is becoming more important as an increasing number of younger patients are treated with radioiodine. If all Swedish hospitals considered the individual biokinetic data the total administrated activity of 131-I would decrease by 10 % (100 GBq) corresponding to a yearly collective effective dose of 17 manSv, thyroid excluded. Seventeen different methods to determine the administered activity of 131-I are in use in 23 Swedish hospitals. Only nine hospitals calculate the administered activity of 131-I using individual biokinetic data. More effort should be done to consider the individual biokinetic data when calculating the administered activity of 131-I and thus decrease unnecessary radiation dose to individual patients, their families and the public.},
  author       = {Jönsson, Helene},
  isbn         = {91-628-5753-3},
  keyword      = {radiobiologi,Radiofarmaceutisk teknik,Radiopharmaceutical technology,absorbed dose. optimise,hyperthyroidism,therapy,131-I,radioiodine,Nukleärmedicin,radiobiology,Nuclear medicine},
  language     = {eng},
  pages        = {105},
  publisher    = {ARRAY(0x8a46198)},
  title        = {Radioiodine Therapy of Hyperthyroidism - Simplified patient-specific absorbed dose planning},
  year         = {2003},
}