Dose-effect relation of interstitial low-dose-rate radiation (Ir192) in an animal tumor model

Journal Article · Mon Jan 01 00:00:00 EST 1990 · International Journal of Radiation Oncology, Biology and Physics; (USA)

DOI:https://doi.org/10.1016/0360-3016(90)90263-J· OSTI ID:7026209

Ruifrok, A C; Levendag, P C; Lakeman, R F; Deurloo, I K; Visser, A G ^[1]

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1. Dr. Daniel den Hoed Cancer Center, Rotterdam (Netherland)

One way to deliver high doses of radiation to deep seated tumors without damaging the surrounding tissue is by interstitial techniques. This is commonly applied clinically; however, biological data of tumor response to interstitial low-dose-rate gamma irradiation are scarce. Therefore, we have studied the response of rhabdomyosarcoma R1 tumors implanted in the flanks of female Wag/Rij rats using an interstitial Ir192 afterloading system. A template was developed by which four catheters can be implanted in a square geometry with a fixed spacing. Subsequently four Ir192 wires of 2 cm length each are inserted. For dose prescription the highest isodose enveloping the tumor volume was chosen. Interstitial irradiation was performed using tumor volumes of 1500-2000 mm3. A range of minimum tumor doses of 20 up to 115 Gy were given at a mean dose-rate of 48 cGy/hr. Dose-effect relations were obtained from tumor growth curves and tumor cure data, and compared to data from external irradiation. The dose required for 50% cures with interstitial irradiation (TCD50) appears to be 95 +/- 9 Gy. The TCD50 for low-dose-rate interstitial gamma irradiation is 1.5 times the TCD50 for single dose external X ray irradiation at high dose rates, but is comparable to the TCD50 found after fractionated X ray irradiation at high dose rate. Sham treatment of the tumors had no effect on the time needed to reach twice the treatment volume. The growth rate of tumors regrowing after interstitial radiotherapy is not markedly different from the growth rate of untreated (control) tumors (volume doubting time 5.6 +/- 1 day), in contrast to the decreased growth rate after external X ray irradiation.

• OSTI ID: 7026209
• Journal Information: International Journal of Radiation Oncology, Biology and Physics; (USA), Vol. 18:1; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
SARCOMAS
RADIOTHERAPY
AFTERLOADING
DOSE-RESPONSE RELATIONSHIPS
EXPERIMENTAL NEOPLASMS
IRIDIUM 192
RADIATION DOSES
RADIATION SOURCE IMPLANTS
RATS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
DISEASES
DOSES
ELECTRON CAPTURE RADIOISOTOPES
HEAVY NUCLEI
IMPLANTS
INTERNAL CONVERSION RADIOISOTOPES
IRIDIUM ISOTOPES
ISOMERIC TRANSITION
ISOTOPES
MAMMALS
MEDICINE
NEOPLASMS
NUCLEAR MEDICINE
NUCLEI
RADIATION SOURCES
RADIOISOTOPES
RADIOLOGY
RODENTS
THERAPY
VERTEBRATES
550603* - Medicine- External Radiation in Therapy- (1980-)