Effect of geometric errors in the reconstruction of /sup 192/Ir seed implants

Journal Article · · Med. Phys.; (United States)

OSTI ID:6707087

Rosen, I I; Khan, K M; Lane, R G; Kelsey, C A

In the treatment of tumors using interstitial implants of radioactive seeds, the accuracy of computed dose distributions depends upon the accuracy with which the three-dimensional source geometries are reconstructed from radiographs of the implants. The effect of geometric reconstruction errors in /sup 192/Ir seed implants were studied, using tumor dose as the measure. Tumor dose was defined as the average dose around the periphery of the treatment volume. Three ideal mathematical implants and five actual patient implants were used. The implants were distorted by randomly moving a specified number of seeds a specified distance. Tumor doses were directly calculated for the ideal implants. For the actual implants, isodose distributions were plotted and were read by a radiotherapist. For both types of implants, percentage errors in the tumor doses were calculated for the distorted reconstructions relative to the correct reconstructions. It was found that the tumor dose was accurate to within 5% if all the seeds were reconstructed to within 0.5 cm of their actual positions. Furthermore, up to 5% of the seeds could be mismatched between films, or otherwise incorrectly reconstructed, with position errors as large as 20 cm, and not change the tumor dose by more than 5%.

• Research Organization: University of New Mexico, Cancer Research and Treatment Center, Albuquerque
• OSTI ID: 6707087
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 9:2; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

550604* -- Medicine-- Unsealed Radionuclides in Therapy-- (1980-)
560151 -- Radiation Effects on Animals-- Man
62 RADIOLOGY AND NUCLEAR MEDICINE
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
DISEASES
DOSES
ELECTRON CAPTURE RADIOISOTOPES
GEOMETRY
HEAVY NUCLEI
IMPLANTS
INTERNAL CONVERSION RADIOISOTOPES
INTERNAL IRRADIATION
IRIDIUM 192
IRIDIUM ISOTOPES
IRRADIATION
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MATHEMATICS
MINUTES LIVING RADIOISOTOPES
NEOPLASMS
NUCLEI
ODD-ODD NUCLEI
PATIENTS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIATION SOURCE IMPLANTS
RADIATION SOURCES
RADIOISOTOPES
SPATIAL DOSE DISTRIBUTIONS
YEARS LIVING RADIOISOTOPES