Functional Image-Guided Radiotherapy Planning in Respiratory- Gated Intensity-Modulated Radiation Therapy (IMRT) for Lung Cancer Patients with chronic obstructive pulmonary disease (COPD)

(Purpose) To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). (Materials and Methods) Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values lower than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung. Two respiratory-gated radiotherapy plans (70 Gy/35 fr) were designed and compared in each patient as follows: 1) Plan A: anatomical IMRTor VMAT plan based on the total lung 2) Plan F: functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (V20: the percentage of total lung volume irradiated with ≥ 20 Gy,MLD:mean dose of total lung) of the two plans were compared. (Results) V20 was lower in Plan F than in Plan A (mean 1.5 %, p= 0.025 in IMRT, mean 1.6 %, p= 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p= 0.083 in IMRT, mean 0.5 Gy, p= 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. (Conclusions) Functional image-guided radiotherapy planning based on LAAin respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant no. 22591385), and a Grant-in-Aid for Scientific Research from the Association for Nuclear Technology in Medicine. This work was partly presented at the 52nd Annual Meeting of the American Society of Radiation Oncology, San Diego, CA, Oct 31 - Nov 4, 2010

Nerve tolerance to high-dose-rate brachytherapy in patients with soft tissue sarcoma: a retrospective study

BACKGROUND: Brachytherapy, interstitial tumor bed irradiation, following conservative surgery has been shown to provide excellent local control and limb preservation in patients with soft tissue sarcomas (STS), whereas little is known about the tolerance of peripheral nerves to brachytherapy. In particular, nerve tolerance to high-dose-rate (HDR) brachytherapy has never been properly evaluated. In this study, we examined the efficacy and radiation neurotoxicity of HDR brachytherapy in patients with STS in contact with neurovascular structures. METHODS: Between 1995 and 2000, seven patients with STS involving the neurovascular bundle were treated in our institute with limb-preserving surgery, followed by fractionated HDR brachytherapy. Pathological examination demonstrated that 6 patients had high-grade lesions with five cases of negative margins and one case with positive margins, and one patient had a low-grade lesion with a negative margin. Afterloading catheters placed within the tumor bed directly upon the preserved neurovascular structures were postoperatively loaded with Iridium-192 with a total dose of 50 Gy in 6 patients. One patient received 30 Gy of HDR brachytherapy combined with 20 Gy of adjuvant external beam radiation. RESULTS: With a median follow-up of 4 years, the 5-year actuarial overall survival, disease-free survival, and local control rates were 83.3, 68.6, and 83.3%, respectively. None of the 7 patients developed HDR brachytherapy-induced peripheral neuropathy. Of 5 survivors, 3 evaluable patients had values of motor nerve conduction velocity of the preserved peripheral nerve in the normal range. CONCLUSION: In this study, there were no practical and electrophysiological findings of neurotoxicity of HDR brachytherapy. Despite the small number of patients, our encouraging results are valuable for limb-preserving surgery of unmanageable STS involving critical neurovascular structures

Impact on liver position under breath-hold by computed tomography contrast agents in stereotactic body radiotherapy of liver cancer

Background: We investigated variations in liver position relative to the vertebral bone for liver cancer treated with stereotactic body radiation therapy under expiratory phase breath-hold (BH) for treatment with contrast-enhanced-computed tomography (CECT), non-CECT, and cone-beam computed tomography (CBCT). Materials and methods: Seventeen consecutive patients using a contrast enhancement (CE) agent for the CT simulation session for this retrospective study were selected. The first computed tomography (CT) scan without the use of CE agent in the expiratory phase was used for treatment planning (pCT). The remaining three CT scans without a CE agent under expiratory phase BH were acquired successively without repositioning to evaluate the intra-fraction variation in liver position. Furthermore, a three-phase CT scan (arterial, portal, and late phases) accompanied by a CE agent under expiratory phase BH was acquired for target delineation. CBCT scans without the use of a CE agent under expiratory phase BH were acquired for treatment. Inter-fractional variations (non-CECT or CECT) in liver position were measured using the difference between CBCT and pCT or each 3 phase CECT images, respectively. Results: The average ± standard deviations for intrafractional, non-CECT interfractional variations, and CECT interfractional variations were 1.0 ± 1.3, 2.5 ± 2.6, and 6.4 ± 6.4 mm, respectively, in the craniocaudal (CC) direction. Intra- and inter-fractional variations in liver position were relatively small for non-CECT. However, significant inter-fractional liver position variations in CECT were observed in the expiratory phase BH. The position of the liver should be carefully considered when applying CECT images for image-guided radiotherapy

Secondary anaplastic oligodendroglioma after cranial irradiation: a case report

Secondary brain tumors rarely arise after cranial irradiation; among them, meningiomas and glioblastomas are the most common and secondary oligodendroglial tumors the most rare. We present a 48-year-old man who developed an oligodendroglial tumor 38 years after receiving 50 Gy of cranial irradiation to a pineal tumor. He underwent gross total removal of a calcified, ring-enhanced mass in the right temporal lobe. The tumor was histologically diagnosed as anaplastic oligodendroglioma. Our review of previously reported secondary oligodendroglial tumors that developed after cranial irradiation revealed that these rare tumors arose after low-dose cranial irradiation or at the margin of a field irradiated with a high dose. We suggest that secondary oligodendroglial tumors arising after cranial irradiation are more aggressive than primary oligodendrogliomas

Early clinical outcomes of 3D-conformal radiotherapy using accelerated hyperfractionation without intracavitary brachytherapy for cervical cancer

Purpose/Objective: To evaluate the outcome of cervical cancer patients unable to undergo conventional intracavitary brachytherapy (ICBT) treated with 3D-conformal radiotherapy (3DCRT) alone using accelerated hyperfractionation (AHF). Methods and Materials: We reviewed the records of 7 patients who had received definitive radiotherapy with 3DCRT alone using AHF for cervical cancer between 2002 and 2005. FIGO stage was IB (1), IIB (2), IIIA (1), IIIB (2), and IVA (1). The reason we did not perform ICBT was due to patient refusal. In 1 patient with stage IB, a total dose of 65.4 Gy was delivered by local irradiation (LI) only. In 1 patient with stage IIIA, a total dose of 60 Gy was delivered by LI only. In 5 patients with Stage IIB-IV, a median total dose of 70.8 Gy was delivered by combination of whole pelvic irradiation (median dose of 45 Gy) with LI. Median overall treatment time was 42 days. Results: Median follow-up for survival patients was 17 months. Out of 7 patients, 6 patients had CR and 1 patient had PR. The response rate was 100%.0 The 2-year local control rate was 85.7%.0 Of these patients, 5 are alive without disease and 1 is alive with lung metastasis. Conclusions: Our outcomes suggest that 3DCRT using AHF may be a promising as a definitive treatment for cervical cancer when ICBT is not able to be performed