High-dose Intraoperative Radiation Research Articles

Is There a Role for Intraoperative Radiation Therapy in Patients with Resected Pancreatic Adenocarcinoma?

Is There a Role for Intraoperative Radiation Therapy in Patients with Resected Pancreatic Adenocarcinoma?

Dosimetry of High Intensity Electron Beams Produced by Dedicated Accelerators in Intra-Operative Radiation Therapy (IORT)

The technique of High Dose Intra-Operative Radiation Therapy (HDR-IORT) consists in the delivery of irradiation immediately following the removal of a cancerous mass, where the same incision is used to direct the radiation to the tumour bed. Given its particular characteristics, IORT requires dose measurements that are different from those requested in external radiotherapy treatments. The main reason lies in the fact that in this case a single high dose must be delivered to a target volume whose extension and depths will be determined directly during the operation. Since the possibility of devising a treatment plan using a TPS (Treatment Planning System) is not available, it is necessary to know the physical and geometric characteristics of the beam. Defining the physical characteristics of the beam entails both measuring the delivered dose and defining (monitoring) procedures. In any case a much higher dose will be released than occurs with conventional external accelerators. The ionization chamber recommended by the standard protocols for radiotherapy cannot be used because of the ion recombination inside the gas. In this work we propose the use of a calorimetric phantom, the Dosiort, to measure the beam properties. We describe the main characteristics and some preliminary results of the Dosiort System, which is proposed within the framework of a research project of the INFN (Italian National Institute of Nuclear Physics). The set-up is a solid phantom of density approaching 1 g/cm3 with sensitive layers of scintillating fibres at fixed a position in a calorimetric configuration for the containment of electrons of energy 4-12 MeV. The prototype will be able to define the physical and geometrical characteristics of the electron beam (energy, isotropy, homogeneity, etc) and to measure the parameters needed to select the energy, the intensity and the Monitor Units (MU) for the exposition: Percentage Depth Dose; Beam profiles; Isodose curves; Values of dose for MU.

Study of quadrant high-dose intraoperative radiation therapy for early-stage breast cancer

Partial breast irradiation has been tested in limited pilot studies and shown to provide acceptable cosmesis, minimal toxicity and adequate local control. The aim of this study was to determine the feasibility of using quadrant high-dose intraoperative radiation therapy (IORT) for the treatment of early-stage breast cancer. Fifty-two women with early-stage breast cancer were treated with breast-conserving therapy and IORT between October 2002 and January 2006. The first 18 women received a radiation dose of 20 Gy. The protocol was then amended and the remaining 34 women were treated with 18 Gy. Each patient was evaluated after surgery, and at 3, 6 and 12 months; complications, toxicity and cosmetic outcomes were recorded by the breast surgeon. Women treated with 18 Gy appeared to have a more favourable cosmetic outcome compared with the earlier treatment group. At last follow-up, none of the women treated on the protocol had a breast recurrence. Experience suggests that this IORT technique is feasible, although further follow-up is necessary to assess its therapeutic value.

Radical surgical resection and high-dose intraoperative radiation therapy (HDR-IORT) in patients with recurrent gynecologic cancers

Objective: To determine the outcome for patients with recurrent gynecologic tumors treated with radical resection and combined high-dose intraoperative radiation therapy (HDR-IORT). Methods and Materials: Between November 1993 and June 1998, 17 patients with recurrent gynecologic malignancies underwent radical surgical resection and high-dose-rate brachytherapy. The mean age of the study group was 49 years (range 28–72 years). The site of the primary tumor was the cervix in 9 (53%) patients, the uterus in 7 (41%) patients, and the vagina in 1 (6%) patient. The treatment for the primary disease was surgery with or without adjuvant radiation in 14 (82%) patients and definitive radiation in 3 (18%) patients. The current surgery consisted of exenterative surgery in 10 (59%) patients and tumor resection in 7 (41%) patients. Complete gross resection was achieved in 13 (76%) patients. The mean HDR-IORT dose was 14 Gy (range 12–15). Additional radiation in the form of permanent Iodine-125 implant was given to 3 of 4 patients with gross residual disease. The median peripheral dose was 140 Gy. Results: With a median follow-up of 20 months (range 3–65 months), the 3-year actuarial local control (LC) rate was 67%. In patients with complete gross resection, the 3-year LC rate was 83%, compared to 25% in patients with gross residual disease, p < 0.01. The 3-year distant metastasis disease-free and overall survival rates were 54% and 54%, respectively. The complications were as follows: gastrointestinal obstruction, 4 (24%); wound complications, 4 (24%); abscesses, 3 (18%); peripheral neuropathy, 3 (18%); rectovaginal fistula, 2 (12%); and ureteral obstruction, 2 (12%). Conclusion: Radical surgical resection and combined IORT for patients with recurrent gynecologic tumors seems to provide a reasonable local-control rate in patients who have failed prior surgery and/or definitive radiation. Patient selection is very important, however, as only those patients with complete gross resection at completion of surgery appear to benefit most from this radical approach in the salvage setting.

165 Radical surgical resection and high dose intra-operative radiation therapy (HDR-IORT) in patients with recurrent gynecologic cancers

165 Radical surgical resection and high dose intra-operative radiation therapy (HDR-IORT) in patients with recurrent gynecologic cancers

Very high-dose intraoperative radiation therapy for osteosarcomas

Very high-dose intraoperative radiation therapy for osteosarcomas

Short- and long-term histopathological changes in the canine liver following single high dose intraoperative radiation therapy (IORT)

Purpose: The histopathological changes in the canine liver following single high-dose intraoperative radiation therapy (IORT) were investigated in order to establish the tolerance of liver tissue to IORT, thus providing a framework for clinical IORT treatment of patients with metastatic disease to the liver. Materials and methods: Following partial resection of the liver, IORT in doses of 10, 20, 25, or 30Gy was applied to the resection plane and a non-surgically manipulated part of the liver of 25 beagles. Results: There were no postoperative complications, and no morbidity or mortality during a maximal follow-up of 5 years. Dogs were killed at 3 months, and 1, 2, 3 and 5 years following IORT. Light microscopic examination revealed capsular thickening, severe parenchymal fibrosis, liver cell atrophy, and bile duct proliferation at the irradiated area 1-2 years following IORT. At 3-5 years, however, only mild parenchymal changes were found that consisted of slight periportal fibrosis, an incidental portal...

Short- and long-term histopathological changes in the canine liver following single high-dose intraoperative radiation therapy (IORT)

Purpose: The histopathological changes in the canine liver following single high-dose intraoperative radiation therapy (IORT) were investigated in order to establish the tolerance of liver tissue to IORT, thus providing a framework for clinical IORT treatment of patients with metastatic disease to the liver. Materials and methods: Following partial resection of the liver, IORT in doses of 10, 20, 25, or 30Gy was applied to the resection plane and a non-surgically manipulated part of the liver of 25 beagles. Results: There were no postoperative complications, and no morbidity or mortality during a maximal follow-up of 5 years. Dogs were killed at 3 months, and 1, 2, 3 and 5 years following IORT. Light microscopic examination revealed capsular thickening, severe parenchymal fibrosis, liver cell atrophy, and bile duct proliferation at the irradiated area 1-2 years following IORT. At 3-5 years, however, only mild parenchymal changes were found that consisted of slight periportal fibrosis, an incidental portal-central fibrous septum and vascular changes with endothelial proliferation and focal arteriolar hyalinosis. Conclusions: This study demonstrated that following partial hepatic resection, IORT to the liver in the canine model can be applied safely, without short- or long-term treatment morbidity. Although doses up to 30Gy resulted in severe local tissue damage 1-2 years following IORT, these changes were largely reversible due to hepatic regeneration.

Intraoperative irradiation delays anastomotic repair in rat colon

There exists a growing interest in intraoperative radiation therapy as a treatment modality for large-bowel cancer. Since such therapy could interfere with wound repair, we investigated its effects on early healing of colonic anastomoses. After resection of 1 cm of colon, rats were irradiated with a single dose of 25 Gy, either to the proximal limb (P group) or to both proximal and distal limbs of the bowel (PD group) before anastomotic construction. Both groups were compared with a sham-irradiated control group. Animals were killed 3, 7, or 14 days after operation, and healing was assessed by mechanical and biochemical (collagen) parameters. Three days after operation, bursting pressure was significantly lowered in the P group, whereas in the PD group both bursting pressure and breaking strength were strongly reduced. At day 7, the breaking strength was still reduced in the PD group, but not significantly so in the P group. The collagen synthetic capacity of the anastomotic segments was significantly lowered in both irradiated groups at day 3, resulting in a diminished collagen concentration in the actual wound area after 7 days. At 14 days after operation, no differences in strength were found between control and irradiated groups, while anastomotic hydroxyproline levels were significantly higher in both the P and PD groups than in the control group. High-dose intraoperative radiation therapy delays the healing of colonic anastomoses; it transiently reduces strength, probably as a result of a diminished accumulation of collagen.