ABSTRACT
Intensity-modulated radiation therapy (IMRT) is gaining acceptance as a standard treatment technique for advanced squamous cell carcinoma (SCC) of the oropharynx. Dose to the uninvolved larynx and surrounding structures can pose a problem in patients with significant neck disease, potentially compromising laryngeal function and quality of life. Tomotherapy may allow greater laryngeal sparing. Seven patients with stage IV SCC of the oropharynx were replanned using Tomotherapy version 3.1. All contours/planning target volumes (PTVs) from the original plans were preserved, with the exception of the larynx, which was drawn to include all soft tissue encompassed by the thyroid/cricoid cartilage. A simultaneous integrated boost technique was used with PTV 1, 2, and 3 receiving 69.96, 59.40, and 54.00 Gy, respectively in 33 fractions. Dosimetry was evaluated via the Pinnacle treatment planning system (TPS). Equivalent uniform dose (EUD) was calculated from the dose volume histogram (DVH) using the general method with "a" = 5.0. Mean larynx dose for all patients was 24.4 Gy. Mean EUD to the larynx was 34.2 Gy. Homogeneity was adequate; average maximum dose was 109.7% of the highest prescription. All other organs at risk (OAR) were adequately spared. Tomotherapy can spare the uninvolved larynx in the setting of advanced SCC of the oropharynx to levels that are similar to or better than those reported with other techniques. Sparing is achieved without compromising target coverage or other OAR sparing. The clinical benefit of this sparing remains to be determined in a prospective study.
Subject(s)
Carcinoma/radiotherapy , Larynx , Oropharyngeal Neoplasms/radiotherapy , Radiotherapy, Intensity-Modulated , Humans , Radiation Protection/methods , Radiotherapy Dosage , Retrospective StudiesABSTRACT
OBJECTIVES: Static field intensity modulated radiation therapy (IMRT) has demonstrated dosimetric and clinical benefits over 3-dimensional conformal radiation therapy. TomoTherapy is a unique form of IMRT that may offer further improvements. METHODS: The study population consisted of 15 patients with low-risk prostate cancer treated at Rush University with TomoTherapy (n = 7) or IMRT (n = 8). For each patient, both a TomoTherapy plan and an IMRT plan were generated using identical planning objectives. The planning target volume (PTV) was defined as the prostate and proximal seminal vesicles plus a margin. The prescription dose was 7740 cGy in 43 fractions. Radiation Therapy Oncology Group (RTOG) normal tissue guidelines were used as constraints, and the PTV coverage was made equivalent for the paired plans by equalizing the PTV V100. RTOG benchmark DVH values for the rectum and bladder and mean dose to the penile bulb were recorded. The volume of PTV receiving ≥ 105% of the prescription dose was measured. RESULTS: The mean DVH values for each of the RTOG constraints for rectum and bladder were significantly improved using TomoTherapy. The volume of the PTV that received at least 105% of the dose was higher with IMRT (11.7% vs. 0.2%, <0.001). The mean dose to the penile bulb was higher with TomoTherapy (40.4 Gy vs. 27.4 Gy, P = 0.005). CONCLUSIONS: TomoTherapy offers a more favorable dose distribution to the bladder and rectum, as well as improved target homogeneity in comparison with IMRT.
Subject(s)
Prostatic Neoplasms/radiotherapy , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Intensity-Modulated/methods , Humans , Male , Prostate/diagnostic imaging , Prostatic Neoplasms/diagnostic imaging , Radiation Injuries/prevention & control , Radiometry , Radiotherapy Dosage , Rectum/radiation effects , Risk , Tomography, X-Ray Computed , Urinary Bladder/radiation effectsABSTRACT
Tumors of the thymus are an uncommon entity, constituting 30% and 15% of anterior mediastinal masses in adults and children, respectively. The majority of these tumors are thymomas, with thymic carcinomas less common, and thymic carcinoids exceedingly rare. Recognition of the distinct clinicopathologic behavior of various thymic neoplasms is crucial to providing optimal treatment. Evidence guiding the treatment of early stage thymic tumors is limited secondary to the low incidence and resulting lack of randomized data. Proper management requires a careful analysis of the available literature with particular attention paid to limitations of the existing studies. This article provides a discussion of the presentation, evaluation, diagnosis, surgical techniques, and treatment outcomes relevant to early stage thymomas, thymic carcinomas, and thymic carcinoid tumors. The role of radiation therapy in the management of early stage thymic tumors remains controversial and is discussed in detail.
