Subungual squamous cell carcinoma: A case study.

The purpose of this case study is to describe a dosimetric delivery of radiation to a superficial disease process involving the skin and bone of the distal finger. A 76-year-old male patient presented with a subungual squamous cell carcinoma (SCC) of the left distal index finger with bony involvement. The patient refused conventional surgical treatment but agreed to external beam radiation therapy (EBRT). There is a gap in the current literature describing how to successfully immobilize fingers and which EBRT modality is dosimetrically advantageous in treating them. The construction of a simple immobilization method with the patient in a reproducible position is described. The use of photons and electrons were compared ultimately showing photons to be dosimetrically advantageous. Long-term efficacy of the treatment was not evaluated because of patient noncompliance.

Dosimetric comparison of intensity-modulated solutions for intact prostate cancer.

The purpose of this study is intended to investigate the implementation of a modified class solution for intact prostate intensity-modulated radiation therapy (IMRT). The class solution uses 2 additional optimization structures intended to increase target conformity and decrease unnecessary dose to healthy tissue. A total of 10 randomly selected intact prostate IMRT patients were chosen for this retrospective study. Each of the original IMRT plans was compared with a modified class solution. The class solution implemented 2 additional optimization structures. The 95_OPT was intended to increase target conformity, and the Avoidance_3780 was intended to reduce normal tissue. Each plan was evaluated for minimum, maximum, and mean doses to the target. Additionally, mean normal tissue dose, total monitor units (MUs), and segments were investigated. Conformity index and normal healthy index were also compared. All comparisons were evaluated using a paired t-test using GraphPad software. Evaluations of MUs; segments; minimum, maximum, mean target doses; mean normal tissue dose; and conformity index did not demonstrate a significant difference between the modified class solution and the original plans. However, evaluation of healthy tissue conformity index indicated a significant difference. Overall, 70% of the original plans failed to demonstrate a satisfactory score (< 0.6) of properly sparing normal healthy tissue, whereas 70% of the modified plans exhibited a satisfactory score (> 0.6). Most (90%) of the modified plans demonstrated a greater number of segments than the compared original plan. A modified class solution provides a good starting point for planning intact prostate cancer. The addition of the Avoidance_3780 structure increases the healthy tissue conformity index score.

A comprehensive clinical 3-dimensional dosimetric analysis of forward planned IMRT and conventional wedge planned techniques for intact breast radiotherapy.

A forward planned intensity modulated technique was initiated for intact breasts radiotherapy (FPIMRT). Forty-three patients were selected to compare dose distributions achieved by FPIMRT to dose distributions produced by conventional wedge techniques (CW). For the simulation process, the treatment field margins were clinically defined by a physician, and a set of fiducial reference markers was placed on the patient. A computed tomography (CT) scan was then performed and the images were transferred to a 3-dimensional (3D) treatment planning system (TPS). The breast tissue was then contoured to allow for a quantitative dose volume analysis. The treatment plan was initially generated with conventional tangential beam arrangements and open fields. Multiple multileaf collimator (MLC) shaped segments were created for each tangential beam in an effort to produce dose homogeneity throughout the breast. 6-MV photon beams were used for treatment unless acceptable dose homogeneity could not be achieved due to large breast size. In this case, the beam energies of selected segments were modified to 15-MV. Once the FPIMRT plan was created, additional plans were generated using the same beam geometry and 2 tangential open fields with CW techniques and 15 degrees wedges (15DW), 30 degrees wedges (30DW), 45 degrees wedges (45 DW), and 60 degrees wedges (60DW). The dose distributions generated by the CW plans were then compared to the FPIMRT plan. This process was repeated for each patient, and the patient group was divided into 3 categories based on breast volume (small, medium, and large). Both point dose relationships, which compared global hot spot (GHS) magnitude and location and dose volume relationships, which compared breast volume coverage of the 105% and 110% isodose lines (IDL) relative to the prescribed dose (PD), were explored. For the patient group in our study, FPIMRT produced the smallest average GHS and the most evenly distributed location of GHS for all breast size categories when compared to all CW techniques. FPIMRT also produced the smallest average breast volume receiving greater than 105% of the PD (V(a105)) for the small- and medium-size breast patients and the smallest average breast volume receiving greater than 110% of the PD (V(a110)) for all breast size categories when compared to all CW techniques.