Construction of a Simple Rectum Model Using Image Guidance in Prostate Patients Treated with 3D Conformal Radiotherapy

Purpose: To evaluate the performance of a rectum model in predicting late rectal toxicity of prostate patients undergoing 3D conformal radiation therapy while following a dietary protocol combined with image guidance. Methods: A linear accelerator equipped with a Cone Beam Computed Tomography (CBCT) system was used to treat 20 patients who were following a dietary protocol. The set-up was verified by co-registering CBCT scans with the planning CT scan (pCT). A mean dose volume histogram () as the arithmetical mean of the rectum DVHs from each CBCT scan was obtained. A suitably defined 3D rectum model (Average Rectum, AR) was defined and its DVH (DVHAR) was calculated. DVHs were also evaluated for the first five CBCT scans using both methods (5 >?and DVHAR5). The Lyman-Kutcher-Burman NTCP model with QUANTEC parameters was used to compare the calculated DVHs. The QUANTEC dose values were used to describe the time behaviour of the relative volumes using the Gamma Distribution for the frequency of the relative rectum volumes at each QUANTEC dose value. Results: No statistically significant differences between NTCPAR5 and NTCPAR and between NTCP and NTCP were found. The best agreement with the observed toxicity rate (0%) was obtained form DVHAR. The Gamma Distributions of the rectum volumes at the QUANTEC dose levels were found to be highly variable among the patients. Conclusions: Both dietary protocol and image guidance were found effective in limiting late rectal toxicity. AR was a better predictor for late rectal toxicity and better described the rectum volume during the treatment course. Finally, from the Gamma distributions, and from our toxicity data, we can suggest V75 as the best predictor of late rectal toxicity.

Hypofractioned Radiation Therapy in the Treatment of Partial Breast: 30 Gy in Five Consecutive Fractions

Background and Purpose: Recent prospective studies have explored the partial breast irradiation (PBI) for patients with early-stage breast cancer using different technical approaches. The purpose of this study is to explore feasibility, tumor control and acute and late toxicity of a specific hypo-fractionated 3D-CRT when treating postmenopausal patients with early breast cancer with partial breast irradiation, using five fractions in five consecutive days. Materials and Methods: Ten patients, aged ≥ 70 underwent breast conservative surgery for invasive breast carcinoma with a complete microscopic resection;no lymphovascular invasion was found and negative axillary node status was assessed. Metal clips were positioned in the surgical bed at the time of surgery. All of the patients provided an informed consent for breast irradiation. Seven patients received Tamoxifen. Of the ten patients, five were treated for left breast disease, and five for right breast disease. The dose fractionation schedule was 3000 cGy delivered to the isocenter in 5 fractions (600 cGy/fr) using 6 MV photons. According to the linear quadratic model and an α/β ratio of 4 Gy this prescription is equivalent to 50 Gy in a standard 2-Gy fractionation schedule. Patients were treated in the supine position. A comercial breast board was used as immobilization device in order to keep the arms of the patient raised. The clinical target volume (CTV) was drawn with a uniform 1-cm three-dimensional margin around the surgical clips. The CTV was limited to 3 mm from the skin surface and 3 mm from the lung-chest wall interface. A three-dimensional margin was added to the CTV to obtain the planning target volume (PTV). The ipsilateral and controlateral breast, the ipsilateral and controlateral lung, heart and spinal cord were contoured as organs at risk (OAR). The treatment was developed using Precise Plan Treatment Planning System and four no-coplanar fields. The constraints used have been: uninvolved breast (ipsilateral breast-PTV): V15 ≤ 50%;heart: V3 ≤ 10%;ipsilateral lung: V10 ≤ 20%;controlateral lung: V5 ≤ 10% and controlateral breast: maximum dose ≤ 1 Gy. We required PTV coverage of ≥ 90%. Patient set-up was verified every day before treatment using portal images. No tumour bed boost was delivered. Clinical assessments of early normal tissue reaction were carried out every day during radiotherapy and 10 days after the end of the treatment. After radiotherapy, we visited all patients every 3 months during the first 2 years and every six month thereafter. Frontal and lateral pictures of the breast were taken on the first day of treatment (baseline), at the end of treatment, 10 days after the end of treatment and at the first follow-up. Any change in breast appearance compared with the baseline picture was scored on a four-point RTOG for acute and late radiation morbidity scoring scale. Results: No local or distant recurrences was observed and then confirmed by mammograms performed every year and breast ultrasound performed every six months. For acute and late toxicity, only 2 patients developed acute effects at the end of the treatment. Conclusion: The clinical outcomes observed in ten patients demonstrate a good feasibility of the schedule adopted both in terms of tumour control and acute and late toxicity, with good cosmetics results. Long term follow-up and a large number of patients will be needed for full evaluation.

Orbital Involvement in Multiple Myeloma: A Case Report

Purpose: To report a retro-orbital localization of Multiple Myeloma (MM) describing its treatment and clinical result. Case report: A 50-years-old male patient with Magnetic Resonance Imaging (MRI) evidence of a retro-orbital mass with exophthalmos, due to the pathological diagnosis of MM, was referred for Radiation Therapy (RT). Discussion: The orbital involvement in Multiple Myeloma is rare and few cases are reported in the literature. The treatment of choice is RT alone with a prescribed dose ranging between 40 Gy and 45 Gy. In our patient the retro-orbital lesion, measuring 26 × 16 mm, was treated with Intensity Modulated Radiotherapy Technique (IMRT) delivering 4400 cGy with conventional fractionation. The treatment was well tolerated, the patient experienced a complete regression of the exophthalmos without any significant side effect.