Multi-planner validation of RapidPlan knowledge-based model for volumetric modulated arc therapy in prostate cancer.

PURPOSE: To investigate the performance of a model-based optimization process for volumetric modulated arc therapy (VMAT) applied to prostate cancer patients with the multi-planner. METHODS AND MATERIALS: The 120 prostate plans for VMAT treatment were entered into the database system of the RapidPlan (RP) knowledge-based treatment planning. The treatment planning data for each plan was used to create and train the RP model. Twelve prostate cancer cases were selected and were used for planning by a manual of 12 planners based on the clinical protocol for dose constraints. Then, the treatment plans for each patient were compared with the RP model plans and analyzed with Wilcoxon tests. RESULTS: On average, the RP models can estimate comparable doses among all planner plans and clinical plans for the PTV, which Dmax , D95% , D98% , HI, and CI were used to evaluate. For the normal organ doses of the bladder, rectum, penile bulb, and femoral head, all RP model plans showed comparable or better dose sparing than all planner plans and clinical plans. Moreover, the average planning time of the RP model was faster than manual plans by about two times. The RP model can significantly reduce the variation dose of the normal organs compared with the manual plans among the planners. CONCLUSION: The automated plans of the RP model might benefit from further fine-tuning of the dose constraints of the normal organs, although both procedure plans are acceptable and fulfill the clinical protocol goals so that the RP model can enhance the efficacy and quality of plans.

Validation of RapidPlan Knowledge-Based Model for Volumetric-Modulated Arc Therapy in Prostate Cancer.

Aims and Objectives: This study aims to investigate the viability of using RapidPlan (RP) knowledge-based (KB) treatment plans to initiate the new prostate volumetric-modulated arc therapy (VMAT) plans. Materials and Methods: The planning data for 120 prostate VMAT treatment plans were entered into the RP system's database. The database of previous VMAT plans was divided into four model groups for training in the RP system. The models were based on the numbers of 20, 60, and 120 prostate VMAT plans. The model of 120 plans used automated priority and manual priority for the optimization process. The models of 20 and 60 plans used only manual priority for optimization. Each model was validated on 15 cases of new prostate cancer patients by comparing RP model plans against manual clinical plans optimized according to the clinical dose constraints. Results: The RP models can estimate the dose comparable target volume to the manual clinical plan, which evaluated values of Dmax, D95%, D98%, HI, and CI and showed comparable results. For the normal organ doses of the bladder, rectum, penile bulb, and femoral head, all RP models exhibited a comparable or better dose than the manual clinical plan, except for the RP models using the automated priority for the optimization process, which cannot control the rectum dose below the dose constraints. Conclusions: The Varian RP KB planning can produce comparable doses or better doses with the clinical manual in a single optimization, although the RP model uses a minimum requirement of the planning number for the model training. The RP models can enhance the efficacy and quality of plans, which depend on the number of VMAT plans used in RP model training for prostate cancer.

A two-year experience of implementing 3 dimensional radiation therapy and intensity-modulated radiation therapy for 925 patients in King Chulalongkorn Memorial Hospital.

BACKGROUND AND OBJECTIVE: Three dimensional conformal radiation therapy (3D CRT) and intensity-modulated radiation therapy (IMRT) have been implemented at Department of Therapeutic Radiation and Oncology, King Chulalongkorn Memorial Hospital (KCMH) since July 2005. This is the first study in Thailand to evaluate the pattern of care and utilization of 3D CRT and IMRT for treatment in each individual cancer. MATERIAL AND METHOD: Between July 2005 and July 2007, 925 newly diagnosed cancer patients underwent IMRT or 3D CRT at KCMH. The authors retrospectively reviewed the experience and utilization of 3D CRT and IMRT for each disease site and region. RESULTS: There were 471 males and 454 females. There were 332 patients (35.9%) treated with IMRT. Among the 332 IMRT patients, there were 100, 32 and 27 nasopharyngeal, lung and prostate cancers, respectively. On the contrary, 593 patients (64.1%) were treated with 3D CRT. Among these, breast, cervix and lung cancers were the most common diseases. Except for head and neck as well as genitourinary cancer 3D CRT was still the main technique used in more than 60% of the patients at KCMH. CONCLUSION: 3D CRT and IMRT have been successfully implemented at KCMH for 2 years. Three dimensional conformal radiation therapy was still the main technique used in more than 60% of the patients at KCMH. Prospective studies evaluating tumor control and treatment sequelae are expected.

Intensity-modulated radiation therapy in head-and-neck cancer, first report in Thailand.

OBJECTIVE: This is the first report in Thailand to evaluate the efficacy of using intensity-modulated radiotherapy (IMRT) in the primary treatment of head-and-neck cancer. MATERIAL AND METHOD: From July 2005 to March 2006, eighteen patients with head and neck cancer were treated with IMRT, fourteen of which were nasopharyngeal cancer. The median age at diagnosis was 52 years (range 23-58 years). The treatment plan composed of two sequential plans for PTV-low risk (50Gy in 25 fractions) and PTV-high risk (20Gy in 10 fractions). Chemotherapy was given to 13 patients with locoregionally advanced disease (stage T3/T4 and N2/3) using cisplatin (n = 3) or carboplatin (n = 10) every 3 weeks during the course of radiation therapy. RESULTS: The median overall treatment time was 49 days (range, 43-57 days), and 77.8 percent of the patients completed 35 fractions within 50 days. The clinical complete response and partial response rates at 3 months after complete radiation were 71.4% and 28.6%, respectively. However at the median follow-up of 5.6 months, the complete response rate increased to 89%. Treatment break during RT range from 3 to 7 days, was observed in three patients. All of them received concurrent chemoradiation. No distant metastasis was noted. CONCLUSION: The authors' experience of using concurrent chemotherapy with IMRT for a cohort of patients with head and neck carcinoma showed a very high rate response rate at early follow-up. Long-term clinical outcome is expected.