Use Of Conformal Radiation Therapy Research Articles

Importance of Technique, Target Selection, Contouring, Dose Prescription, and Dose-Planning in External Beam Radiation Therapy for Cervical Cancer: Evolution of Practice From EMBRACE-I to II

To describe the evolution of external beam radiation therapy (EBRT) from EMBRACE-I (general guidelines for EBRT) to the initial phase of the EMBRACE-II study (detailed protocol for EBRT). EMBRACE-I enrolled 1416 locally advanced cervical cancer patients treated with chemoradiation including image-guided adaptive brachytherapy during 2008 to 2015. From March 2016 until March 2018, 153 patients were enrolled in the ongoing EMBRACE-II study, which involves a comprehensive detailed strategy and accreditation procedure for EBRT target contouring, treatment planning, and image guidance. EBRT planning target volumes (PTVs), treated volumes (V43Gy), and conformity index (CI; V43Gy/PTV) were evaluated in both studies and compared. For EMBRACE-I, conformal radiation therapy (60% of patients) or intensity-modulated radiation therapy (IMRT) and volumetric arc therapy (VMAT; 40%) was applied with 45 to 50Gy over 25 to 30 fractions to the elective clinical target volume (CTV). For pelvic CTVs (82%), median PTV and V43 Gy volumes were 1549 and 2390mL, respectively, and CI was 1.54. For pelvic plus paraortic nodal (PAN) CTVs (15%), median PTV and V43Gy volumes were 1921 and 2895mL, and CI was 1.51. For pelvic CTVs treated with 45 to 46Gy, the use of conformal radiation therapy was associated with a median V43Gy volume that was 546mL larger than with IMRT/VMAT. For pelvic CTVs treated with IMRT, the use of a dose prescription ≥48Gy was associated with a median V43 Gy volumes that was 428mL larger than with a dose prescription of 45 to 46Gy. For EMBRACE-II, all patients were treated with: IMRT/VMAT, daily IGRT, 45Gy over 25 fractions for the elective CTV, and simultaneously integrated boost for pathologic lymph nodes. For pelvic CTVs (61%), median PTV and V43Gy volumes were 1388 and 1418mL, and CI was 1.02. For pelvic plus PAN CTVs (32%), median PTV and V43Gy volumes were 1720 and 1765mL, and CI was 1.03. From EMBRACE-I to initial II, median V43Gy was decreased by 972mL (41%) and 1130mL (39%), and median CI decreased from 1.54 to 1.02 and 1.51 to 1.03 for pelvic and pelvic plus PAN irradiation, respectively. Application of IMRT/VMAT, IGRT, and a 45-Gy dose provides the potential of higher conformality inducing significant reduction of treated volume. Adherence to a detailed protocol including comprehensive accreditation, as in EMBRACE-II, reduces considerably V43Gy and V50Gy and improves conformality and interinstitutional consistency.

Nomograms Inserted into NCCN Prostate Cancer Guidelines

Nomograms Inserted into NCCN Prostate Cancer Guidelines

Preliminary results of conformal radiation therapy for medulloblastoma.

Radiation therapy for medulloblastoma consists of postoperative irradiation of the intracranial and spinal subarachnoid volume with an additional boost to the primary site of disease in the posterior fossa. The entire posterior fossa is usually included in the boost volume. Conformal radiation therapy techniques may be used to boost the primary site alone and substantially reduce the dose received by normal tissues, including the supratentorial brain, the middle and inner ear, and the hypothalamus. Using these techniques to irradiate only the tumor bed or residual tumor and not the entire posterior fossa represents a new paradigm in the treatment of medulloblastoma. In this study, we examine the use of conformal radiation therapy in the treatment of 14 patients with medulloblastoma. These patients were treated with multiple static, individually shaped, noncoplanar beams directed at the primary site after craniospinal irradiation. Excluding two patients who had previously received irradiation to the posterior fossa, the mean dose delivered to the primary site was 5715 cGy. Among the medulloblastoma patients (n = 10) who received immediate postoperative radiation therapy, no failures have occurred with a median follow-up of 42 months (range from 30 to 54 months). To demonstrate the differences in the distribution of dose to normal tissues when comparing conventional and conformal techniques, dose-volume histograms of the total brain, middle and inner ear, hypothalamus, and temporal lobe were created and presented for an example case. The neurologic, neuroendocrine, and neurocognitive outcome for patients with medulloblastoma may be influenced with the use of conformal radiation therapy. The use of these techniques should be formally tested in prospective studies of rigorously staged patients with failure rate monitoring.

Volumetric and dosimetric evaluation of radiation treatment plans: radiation conformity index

Purpose: The use of conformal radiation therapy has grown substantially during the last years since three-dimensional (3D) treatment planning systems with beams-eye-view planning has become commercially available. We studied the degree of conformity reached in clinical routines for some common diagnoses treated at our department by calculating a radiation conformity index (RCI).Methods and Materials: The radiation conformity index, determined as the ratio between the target volume (PTV) and the irradiated volume, has been evaluated for 57 patients treated with 3D treatment plans.Results and Conclusion: The RCI was found to vary from 0.3 to 0.6 (average 0.4), a surprisingly low figure. The higher RCI is typical for pelvic treatments (e.g., prostate) and stereotactic treatments. The lower RCI is found for extended tumors, such as mammary carcinomas where the adjacent nodes are included. The latter is also valid for most lung cancer patients studied. The RCI gives a consistent method for quantifying the degree of conformity based on isodose surfaces and volumes. Care during interpretation of RCI must always be taken, since small changes in the minimum dose can dramatically change the treated volume.

The development of conformal radiation therapy.

The development and clinical use of conformal radiation therapy, and the application of modern computer-controlled radiation therapy treatment techniques to the delivery of conformal therapy, has been a major research area in the field of radiation oncology in recent years. The introduction of three-dimensional (3-D) patient imaging, 3-D treatment planning systems, computer-controlled treatment machines equipped with multileaf collimators, and the continuing increase in computer power and software sophistication has finally allowed the clinical implementation of the kinds of conformal treatment planning and delivery that were envisioned decades ago. The use of 3-D treatment planning in conjunction with conformal treatments and the analysis of clinical normal tissue complications has also begun to give the field the clinical complication (and eventually tumor control) probability data which can be used to truly optimize radiation treatments. At this centennial anniversary of the discovery of the x ray, it is appropriate to look back at the contributions which have led to the current developments in conformal therapy. Few if any of the "new developments" associated with modern computer-controlled conformal therapy (CCRT) are actually new. However, modern technology has finally progressed to the point that we can integrate all of the features that are necessary to really make the concepts work in the clinic. This paper traces some of the developments which have led to the current interest and progress in CCRT treatments. A brief summary of the current status of conformal therapy and the work still to be done is also included.