4 research outputs found
Does intensity-modulated radiation therapy (IMRT) alter prostate size? Magnetic resonance imaging evaluation of patients undergoing IMRT alone
AimTo assess the changes in prostate size in patients with prostate cancer undergoing intensity-modulated radiation therapy (IMRT).BackgroundThe effect of size change produced by IMRT is not well known.Materials and methodsWe enrolled 72 patients who received IMRT alone without androgen-deprivation therapy and underwent magnetic resonance imaging (MRI) examination before and after IMRT. The diameter of the entire prostate in the anterior–posterior (P-AP) and left–right (P-LR) directions was measured. The transitional zone diameter in the anterior–posterior (T-AP) and left–right (T-LR) directions was also measured.ResultsThe average relative P-AP values at 3, 6, 12, 24, and 36 months after IMRT compared to the pre-IMRT value were 0.94, 0.90, 0.89, 0.89, and 0.90, respectively; the average relative P-LR values were 0.93, 0.92, 0.91, 0.91, and 0.90, respectively. The average P-AP and P-LR decreased by approximately 10% during the 12 months post-IMRT, and remained unchanged thereafter. The average relative T-AP values at 3, 6, 12, 24, and 36 months after IMRT compared to the pre-IMRT value were 0.93, 0.88, 0.91, 0.87, and 0.89, respectively; the average relative T-LR values were 0.96, 0.90, 0.91, 0.87, and 0.88, respectively. The average T-AP and T-LR also decreased by approximately 10% during the 12 months post-IMRT, and remained unchanged thereafter. At 12 months after IMRT, the average relative T-AP was significantly lower in patients with recurrence than in those without recurrence.ConclusionsThe average prostate diameter decreased by approximately 10% during the 12 months after IMRT; thereafter remained unchanged
High Tangent Radiation Therapy With Field-in-Field Technique for Breast Cancer
Purpose: We evaluated whether the field-in-field (FIF) technique improves the homogeneity of the target in high tangent radiation therapy (HTRT). Materials and Methods: This study included 30 patients. In total, 3 HTRT plans were created: 1 with conventional opposed fields (Conv-p), 1 with the FIF technique (FIF-p), and 1 with FIF technique using lung-blocked subfields (FIF-LB-p). Results: The maximum dose of the breast and planning target volume (PTV) was significantly lower for FIF-p and FIF-LB-p than Conv-p. Homogeneity index of PTV was also significantly lower for FIF-p and FIF-LB-p than Conv-p. Homogeneity index of the breast or PTV was significantly better for FIF-p than FIF-LB-p. The volumes of the breast or the PTV receiving 95% and 90% of the prescribed dose were also significantly better for FIF-p, indicating the advantages of FIF-p. Conclusions: The FIF technique was useful in HTRT and improved homogeneity in the target
11C-methionine positron emission tomography for target delineation o frecurrent glioblastoma in re-irradiation planning
AimTo define the optimal margin on MRI scans in the re-radiation planning of recurrent glioblastoma using methionine positron emission tomography (MET-PET).BackgroundIt would be very useful if the optimal margin on MRI to cover the uptake area on MET-PET is known.Materials and MethodsCT, MRI, and MET-PET were performed separately over the course of 2 weeks. Among the MRI scans, we used the contrast-enhanced T1-weighted images (Gd-MRI) and T2-weighted images (T2-MRI). The Gd-MRI-based clinical target volume (CTV) (CTV-Gd) and the T2-MRI-based CTV (CTV-T2) were defined as the contrast-enhanced area on Gd-MRI and the high intensity area on T2-MRI, respectively. We defined CTV x mm (x[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]5, 10, 15, 20) as x mm outside the CTV. MET-PET-based CTV (CTV-MPET) was defined as the area of accumulation of MET-PET. We calculated the sensitivity and specificity of CTV-Gd and CTV-T2 following comparison with CTV-MPET, which served as the gold standard in this study.ResultsThe sensitivity of CTV-T2 5[[ce:hsp sp="0.25"/]]mm (98%) was significantly higher than CTV-T2 (87%), and there was no significant difference in the sensitivity between CTV-T2 5[[ce:hsp sp="0.25"/]]mm and CTV T2 10, 15, or 20[[ce:hsp sp="0.25"/]]mm. The sensitivity of CTV-Gd 20[[ce:hsp sp="0.25"/]]mm (97%) was lower than that of CTV-T2 5[[ce:hsp sp="0.25"/]]mm (98%).ConclusionsA margin of at least 5[[ce:hsp sp="0.25"/]]mm around the high intensity area on T2-MRI is necessary in the target volume delineation of recurrent glioblastoma for the coverage of MET-PET findings in re-radiation therapy planning
Treatment outcomes and late toxicities of intensity-modulated radiation therapy for 1091 Japanese patients with localized prostate cancer
AimThis study aimed to evaluate the treatment result of intensity-modulated radiation therapy (IMRT) in a large number of Japanese patients with prostate cancer.BackgroundA total of 1091 patients with localized prostate cancer were recruited between March 2006 and July 2014. The patients were stratified into low- (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]205 [18.8%]), intermediate- (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]450 [41.2%]), high- (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]345 [31.6%]), and very high-risk (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]91 [8.3%]) groups according to the National Comprehensive Cancer Network classification. All patients were irradiated via IMRT at a dose of 74–78[[ce:hsp sp="0.25"/]]Gy with or without androgen-deprivation therapy. The mean follow-up period was 50 months (range, 2–120 months).ResultsThe biochemical failure-free rate (BFFR), the clinical failure-free rate, and the overall survival rate at the 5-year follow-up for all patients was 91.3%, 96.2%, and 99.1%, respectively. In univariate analysis, the prostate-specific antigen (PSA) levels (≤20 vs. >20[[ce:hsp sp="0.25"/]]ng/ml) were significantly correlated with BFFR. A trend toward higher BFFR was noted in patients with a Gleason score (GS) of ≤7 than in patients with GS ≥8. In multivariate analysis, only PSA (≤20 vs. >20[[ce:hsp sp="0.25"/]]ng/ml) was significantly correlated with BFFR. The cumulative incidence rate of gastrointestinal and genitourinary toxicity (≥grade 2) at the 5-year follow-up was 11.4% and 4.3%, respectively.ConclusionsThe findings of this study indicate that IMRT is well tolerated and is associated with both good long-term tumor control and excellent outcomes in patients with localized prostate cancer