Template-based Intensity-Modulated Radiation Therapy: A Cost-effective Intensity-Modulated Radiation Therapy Planning Procedure for Prostate Cancer.

INTRODUCTION: Intensity-modulated radiation therapy (IMRT) has been widely accepted for the treatment of prostate cancer. In comparison with traditional three-dimensional conformal radiation therapy (3D-CRT), it improves local control while minimizing side effects. However, IMRT comes at a significantly higher cost. In this report, we describe the development of template-based IMRT (TB-IMRT) planning for prostate cancer that does not require additional resources above 3D-CRT. METHODS: Twenty patients previously treated using 3D-CRT were retrospectively planned using the TB-IMRT planning technique. Planning target volume coverage, dose to organs at risk, and resource usage were compared between 3D-CRT and TB-IMRT techniques. RESULTS: All 3D-CRT and TB-IMRT plans met the planning guidelines. TB-IMRT compared better than 3D-CRT in terms of the homogeneity index (0.039 ± 0.007 vs. 0.052 ± 0.008) and conformity index (0.866 ± 0.024 vs. 0.752 ± 0.054). TB-IMRT also provided better sparing of organs at risk. Planning times were significantly less for TB-IMRT (average 13.43 ± 2.18 minutes) compared with conventional plans (45.4 ± 17.0 minutes). Times required for patient-specific quality assurance were similar between TB-IMRT and 3D-CRT. CONCLUSIONS: The TB-IMRT technique for prostate allows for all the potential benefits of IMRT without any additional resources above conventional 3D-CRT.

A three-isocenter jagged-junction IMRT approach for craniospinal irradiation without beam edge matching for field junctions.

PURPOSE: Traditionally craniospinal irradiation treats the central nervous system using two or three adjacent field sets. We propose a technique using a three-isocenter intensity-modulated radiotherapy (IMRT) plan (jagged-junction IMRT) which overcomes problems associated with field junctions and beam edge matching and improves planning and treatment setup efficiencies with homogenous target dose distribution. METHODS AND MATERIALS: Treatments for 3 patients with a prescription of 36 Gy in 20 fractions were retrospectively planned with jagged-junction IMRT and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan used three field sets, each with a unique isocenter. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped, and the optimization process smoothly integrated the dose inside the overlapped junction. RESULTS: For jagged-junction IMRT plans vs. conventional technique, the average homogeneity index equaled 0.08 ± 0.01 vs. 0.12 ± 0.02, respectively, and conformity number equaled 0.79 ± 0.01 vs. 0.47 ± 0.12, respectively. The 95% isodose surface covered (99.5 ± 0.3)% of the PTV vs. (98.1 ± 2.0)%, respectively. Both jagged-junction IMRT plans and the conventional plans had good sparing of organs at risk. CONCLUSIONS: Jagged-junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to organs at risk. Results from jagged-junction IMRT plans were better than or equivalent to those from the conventional technique. Jagged-junction IMRT optimization smoothly distributed dose in the junction between field sets. Because there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction, in contrast to conventional techniques. The planning process is also simplified as only one IMRT plan is required for the entire target volume.

Whole brain radiotherapy with hippocampal avoidance and simultaneous integrated boost for 1-3 brain metastases: a feasibility study using volumetric modulated arc therapy.

PURPOSE: To evaluate the feasibility of using volumetric modulated arc therapy (VMAT) to deliver whole brain radiotherapy (WBRT) with hippocampal avoidance and a simultaneous integrated boost (SIB) for one to three brain metastases. METHODS AND MATERIALS: Ten patients previously treated with stereotactic radiosurgery for one to three brain metastases underwent repeat planning using VMAT. The whole brain prescription dose was 32.25 Gy in 15 fractions, and SIB doses to brain metastases were 63 Gy to lesions >or=2.0 cm and 70.8 Gy to lesions <2.0 cm in diameter. The mean dose to the hippocampus was kept at <6 Gy(2). Plans were optimized for conformity and target coverage while minimizing hippocampal and ocular doses. Plans were evaluated on target coverage, prescription isodose to target volume ratio, conformity number, homogeneity index, and maximum dose to prescription dose ratio. RESULTS: Ten patients had 18 metastases. Mean values for the brain metastases were as follows: conformity number = 0.73 +/- 0.10, target coverage = 0.98 +/- 0.01, prescription isodose to target volume = 1.34 +/- 0.19, maximum dose to prescription dose ratio = 1.09 +/- 0.02, and homogeneity index = 0.07 +/- 0.02. For the whole brain, the mean target coverage and homogeneity index were 0.960 +/- 0.002 and 0.39 +/- 0.06, respectively. The mean hippocampal dose was 5.23 +/- 0.39 Gy(2). The mean treatment delivery time was 3.6 min (range, 3.3-4.1 min). CONCLUSIONS: VMAT was able to achieve adequate whole brain coverage with conformal hippocampal avoidance and radiosurgical quality dose distributions for one to three brain metastases. The mean delivery time was under 4 min.