Dosimetric analysis of Tomotherapy-based intracranial stereotactic radiosurgery of brain metastasis.

PURPOSE: This paper analyzes Tomotherapy-based intracranial stereotactic radiosurgery (HTSRS) of brain metastasis targeting two end-points: 1) evaluation of dose homogeneity, conformity and gradient scores for single and multiple lesions and 2) assay of dosimetric criticality of completion of HTSRS procedures. METHODS: 42 treatment plans of 33 patients (53 brain lesions) treated with HTSRS were analyzed. Dose to healthy brain, homogeneity, conformity and gradient indexes were evaluated for each lesion. Influence of Field Length and multiple lesions cross-talk effect were assessed. Treatment interruption and completion was investigated using radiochromic films in order to examine the delivered dose and its robustness to patient intrafraction movement. RESULTS: The average dose homogeneity index was 1.04 ±â€¯0.02 (SD). Average dose conformity and gradient score indexes were 1.4 ±â€¯0.2 and 50 ±â€¯14 respectively. We found a strong correlation of the dose to healthy brain and conformity and gradient indexes with target(s) volume for which analytical functions were obtained. Field Length and cross-talk effect were significantly correlated with poor gradient scores, but were found not to affect dose conformity. CONCLUSIONS: Homogeneity and conformity of HTSRS plans achieved excellent scores, while dose falloff and dose to healthy brain were slightly larger when compared with non-coplanar SRS techniques. Care should be given if treating large (>3 cc) or multiple near in-plane lesions in order to reduce dose to healthy brain. Analysis of interrupted treatments suggests splitting HTSRS treatments in two consecutive fractions in order to prevent target miss and overdosage due to patient intrafraction movement.

A two-step selection of breast cancer patients candidates for exclusive IORT with electrons: a mono-institutional experience.

AIM: To assess the impact of a two-step multiparameter selection on the actual enrollment of women with breast cancer into a prospective intraoperative radiotherapy (IORT) trial. PATIENTS AND METHODS: From September 2009, a prospective clinical trial was started in order to deliver adjuvant exclusive single -fraction IORT to patients with early breast cancer. To select patients meeting suitable eligibility criteria for the clinical trial, a two-step decision process was developed: at pre-surgical examination (first step) and during surgery (second step). RESULTS: A series of 464 patients with breast cancer was analysed: at the first step, out of 464 patients, 333 (71%) were considered eligible for the IORT protocol; at the second step, out of 333 patients, 199 (60%) met the eligibility criteria and received the IORT fraction according to the criteria of the controlled trial. CONCLUSION: In our experience, the ultimate rate of patients who enrolled in the IORT clinical trial after the two-step decision process was 43%.