Comparison of three-dimensional (3D) conformal proton radiotherapy (RT), 3D conformal photon RT, and intensity-modulated RT for retroperitoneal and intra-abdominal sarcomas.

To compare three-dimensional conformal proton radiotherapy (3DCPT), intensity-modulated photon radiotherapy (IMRT), and 3D conformal photon radiotherapy (3DCRT) to predict the optimal RT technique for retroperitoneal sarcomas. 3DCRT, IMRT, and 3DCPT plans were created for treating eight patients with retroperitoneal or intra-abdominal sarcomas. The clinical target volume (CTV) included the gross tumor plus a 2-cm margin, limited by bone and intact fascial planes. For photon plans, the planning target volume (PTV) included a uniform expansion of 5 mm. For the proton plans, the PTV was nonuniform and beam-specific. The prescription dose was 50.4 Gy/Cobalt gray equivalent CGE. Plans were normalized so that >95% of the CTV received 100% of the dose. The CTV was covered adequately by all techniques. The median conformity index was 0.69 for 3DCPT, 0.75 for IMRT, and 0.51 for 3DCRT. The median inhomogeneity coefficient was 0.062 for 3DCPT, 0.066 for IMRT, and 0.073 for 3DCRT. The bowel median volume receiving 15 Gy (V15) was 16.4% for 3DCPT, 52.2% for IMRT, and 66.1% for 3DCRT. The bowel median V45 was 6.3% for 3DCPT, 4.7% for IMRT, and 15.6% for 3DCRT. The median ipsilateral mean kidney dose was 22.5 CGE for 3DCPT, 34.1 Gy for IMRT, and 37.8 Gy for 3DCRT. The median contralateral mean kidney dose was 0 CGE for 3DCPT, 6.4 Gy for IMRT, and 11 Gy for 3DCRT. The median contralateral kidney V5 was 0% for 3DCPT, 49.9% for IMRT, and 99.7% for 3DCRT. Regardless of technique, the median mean liver dose was <30 Gy, and the median cord V50 was 0%. The median integral dose was 126 J for 3DCPT, 400 J for IMRT, and 432 J for 3DCRT. IMRT and 3DCPT result in plans that are more conformal and homogenous than 3DCRT. Based on Quantitative Analysis of Normal Tissue Effects in Clinic benchmarks, the dosimetric advantage of proton therapy may be less gastrointestinal and genitourinary toxicity.

Swanson EL ，Indelicato DJ ，Louis D ，Flampouri S ，Li Z ，Morris CG ，Paryani N ，Slopsema R ... -  《-》

Protons offer reduced normal-tissue exposure for patients receiving postoperative radiotherapy for resected pancreatic head cancer.

To determine the potential role for adjuvant proton-based radiotherapy (PT) for resected pancreatic head cancer. Between June 2008 and November 2008, 8 consecutive patients with resected pancreatic head cancers underwent optimized intensity-modulated radiotherapy (IMRT) treatment planning. IMRT plans used between 10 and 18 fields and delivered 45 Gy to the initial planning target volume (PTV) and a 5.4 Gy boost to a reduced PTV. PTVs were defined according to the Radiation Therapy Oncology Group 9704 radiotherapy guidelines. Ninety-five percent of PTVs received 100% of the target dose and 100% of the PTVs received 95% of the target dose. Normal tissue constraints were as follows: right kidney V18 Gy to <70%; left kidney V18 Gy to <30%; small bowel/stomach V20 Gy to <50%, V45 Gy to <15%, V50 Gy to <10%, and V54 Gy to <5%; liver V30 Gy to <60%; and spinal cord maximum to 46 Gy. Optimized two- to three-field three-dimensional conformal proton plans were retrospectively generated on the same patients. The team generating the proton plans was blinded to the dose distributions achieved by the IMRT plans. The IMRT and proton plans were then compared. A Wilcoxon paired t-test was performed to compare various dosimetric points between the two plans for each patient. All proton plans met all normal tissue constraints and were isoeffective with the corresponding IMRT plans in terms of PTV coverage. The proton plans offered significantly reduced normal-tissue exposure over the IMRT plans with respect to the following: median small bowel V20 Gy, 15.4% with protons versus 47.0% with IMRT (p = 0.0156); median gastric V20 Gy, 2.3% with protons versus 20.0% with IMRT (p = 0.0313); and median right kidney V18 Gy, 27.3% with protons versus 50.5% with IMRT (p = 0.0156). By reducing small bowel and stomach exposure, protons have the potential to reduce the acute and late toxicities of postoperative chemoradiation in this setting.

Nichols RC Jr ，Huh SN ，Prado KL ，Yi BY ，Sharma NK ，Ho MW ，Hoppe BS ，Mendenhall NP ，Li Z ，Regine WF ... -  《-》

Intensity-modulated radiotherapy for soft tissue sarcoma of the thigh.

Hong L ，Alektiar KM ，Hunt M ，Venkatraman E ，Leibel SA ... -  《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》

A treatment planning comparison of intensity modulated photon and proton therapy for paraspinal sarcomas.

Weber DC ，Trofimov AV ，Delaney TF ，Bortfeld T ... -  《INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS》

Consolidative involved-node proton therapy for Stage IA-IIIB mediastinal Hodgkin lymphoma: preliminary dosimetric outcomes from a Phase II study.

To compare the dose reduction to organs at risk (OARs) with proton therapy (PT) versus three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) in patients with mediastinal Hodgkin lymphoma (HL) enrolled on a Phase II study of involved-node radiotherapy (INRT). Between June 2009 and October 2010, 10 patients were enrolled on a University of Florida institutional review board-approved protocol for de novo "classical" Stage IA-IIIB HL with mediastinal (bulky or nonbulky) involvement after chemotherapy. INRT was planned per European Organization for Research and Treatment of Cancer guidelines. Three separate optimized plans were developed for each patient: 3D-CRT, IMRT, and PT. The primary end point was a 50% reduction in the body V4 with PT compared with 3D-CRT or IMRT. The median relative reduction with PT in the primary end point, body V4, was 51% compared with 3D-CRT (p = 0.0098) and 59% compared with IMRT (p = 0.0020), thus all patients were offered treatment with PT. PT provided the lowest mean dose to the heart, lungs, and breasts for all 10 patients compared with either 3D-CRT or IMRT. The median difference in the OAR mean dose reduction with PT compared with 3D-CRT were 10.4 Gy/CGE for heart; 5.5 Gy/CGE for lung; 0.9 Gy/CGE for breast; 8.3 Gy/CGE for esophagus; and 4.1 Gy/CGE for thyroid. The median differences for mean OAR dose reduction for PT compared with IMRT were 4.3 Gy/CGE for heart, 3.1 Gy/CGE for lung, 1.4 Gy/CGE for breast, 2.8 Gy/CGE for esophagus, and 2.7 Gy/CGE for thyroid. All 10 patients benefitted from dose reductions to OARs with PT compared with either 3D-CRT or IMRT. It is anticipated that these reductions in dose to OAR will translate into lower rates of late complications, but long-term follow-up on this Phase II INRT study is needed.

Hoppe BS ，Flampouri S ，Su Z ，Morris CG ，Latif N ，Dang NH ，Lynch J ，Li Z ，Mendenhall NP ... -  《-》