Influence of Prostatic Edema on {sup 131}CS Permanent Prostate Seed Implants: A Dosimetric and Radiobiological Study

Journal Article · Wed Jun 01 04:00:00 EDT 2011 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2010.07.001· OSTI ID:21491777

Jones, Heather A; Huq, M Saiful; Smith, Ryan P ^[1]

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1. Department of Radiation Oncology, University of Pittsburgh Cancer Institute, UPMC Cancer Centers, Pittsburgh, Pennsylvania (United States)

Purpose: To study the influence of prostatic edema on postimplant physical and radiobiological parameters using {sup 131}Cs permanent prostate seed implants. Methods and Materials: Thirty-one patients with early prostate cancer who underwent {sup 131}Cs permanent seed implantation were evaluated. Dose-volume histograms were generated for each set of prostate volumes obtained at preimplantation and postimplantion days 0, 14, and 28 to compute quality indices (QIs) and fractional doses at level x (FD{sub x}). A set of equations for QI, FD{sub x}, and biologically effective doses at dose level D{sub x} (BED{sub x}) were defined to account for edema changes with time after implant. Results: There were statistically significant differences found between QIs of pre- and postimplant plans at day 0, except for the overdose index (ODI). QIs correlated with postimplant time, and FD{sub x} was found to increase with increasing postimplant time. With the effect of edema, BED at different dose levels showed less improvement due to the short half-life of {sup 131}Cs, which delivers about 85% of the prescribed dose before the prostate reaches its original volume due to dissipation of edema. Conclusions: Results of the study show that QIs, FD{sub x}, and BEDs at the level of D{sub x} changed from preneedle plans to postimplant plans and have statistically significant differences (p < 0.05), except for the ODI (p = 0.106), which suggests that at the time of {sup 131}C seed implantation, the effect of edema must be accounted for when defining the seed positions, to avoid the possibility of poor dosimetric and radiobiologic results for {sup 131}Cs seed implants.

• OSTI ID: 21491777
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 80; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BETA DECAY RADIOISOTOPES
BODY
CESIUM 131
CESIUM ISOTOPES
DAYS LIVING RADIOISOTOPES
DISEASES
DOSES
EDEMA
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
IMPLANTS
INTERMEDIATE MASS NUCLEI
ISOTOPES
MALE GENITALS
NEOPLASMS
NUCLEI
ODD-EVEN NUCLEI
ORGANS
PATHOLOGICAL CHANGES
PROSTATE
RADIATION DOSES
RADIOISOTOPES
SYMPTOMS