Temporal CT changes after hepatic and renal interstitial radiotherapy in acanine model

Purpose: The purpose of this work was to define the temporal CT characteris tics of hepatic and renal ablation following point-source radioablation uti lizing a low energy, photon X-ray source emitted from a miniature probe. Method: Twelve mongrel dogs underwent each of three hepatic and two renal p oint-source radiation ablations. Animals underwent serial, dual phase, spir al CT scans and were killed at 1, 3, and 6 months after treatment. Results: Ablative lesions were clearly visible at 1 month following therapy and consistently diminished in size over the 6 months of follow-up. Lesion size tended to be proportional to dose delivered. Both hepatic and renal l esions were low in attenuation with frequent rim enhancement that diminishe d over time. Hepatic lesions frequently showed transient hepatic attenuatio n differences (THADs). Lesion size appeared independent of proximity to ves sels. Conclusion: Following hepatic or renal interstitial radiotherapy, lesions a re generated that are similar in CT appearance to those produced by other a blative techniques. The presence of rim or THAD enhancement can be seen ear ly on as part of the normal tissue-healing response.