Biomedical subjects

David Gaffney

Publications and source records attributed to David Gaffney.

4 recordsLinked to original sources

PubMed2004

Local-regional radiation therapy after breast reconstruction: what is the appropriate target volume? A case-control study of patients treated with electron arc radiotherapy and review of the literature.

The oncologic safety and cosmetic outcome of immediate breast reconstruction in breast cancer patients requiring radiation therapy remains ill-defined. Between 1980 and 1998, 18 patients were treated at the University of Utah Medical Center with mastectomy, immediate breast reconstruction, and adjuvant radiation therapy delivered via an electron arc technique. A case-control study was performed matching reconstructed patients in a 1:2 ratio with patients undergoing mastectomy without reconstruction, using number of lymph nodes and tumor size. Median follow-up was 61 months for the reconstructed group. Five-year local-regional control, disease-free survival, and overall survival rates were 87%, 58%, and 74% respectively in the reconstructed group, versus 88%, 57%, and 67% respectively in the matched control group. Cosmesis was good/excellent in 11 of 13 living patients (85%). Significant capsular contraction occurred in 18% of prosthetic reconstruction patients, and revisional surgery was required in 24% of prosthetic reconstruction patients. Utilizing the electron arc technique, the median radiation dose to the chest wall at the midlevel of the ribs was 20% of the prescribed dose, and no patient failed deep to the implant. These results suggest that in appropriately selected patients, structures deep to the reconstruction are not at high risk for local-regional recurrence, and immediate breast reconstruction yields comparable local-regional control, disease-free survival, and overall survival rates to nonreconstructed patients, with acceptable cosmetic results.

Adult↗

PubMed2002

Long-term follow-up of RTOG 88-05: twice-daily external irradiation with brachytherapy for carcinoma of the cervix.

PURPOSE: To evaluate the efficacy and toxicity of twice-daily external irradiation to the pelvis with brachytherapy for carcinoma of the cervix in a long-term follow-up study. METHODS AND MATERIALS: This study was designed to administer twice-daily irradiation doses of 1.2 Gy to the pelvis, 5 d/wk. Radiotherapy also included one or two low-dose-rate intracavitary implants, to deliver a total minimal dose of 85 Gy to point A and 65 Gy to the lateral pelvic lymph nodes. RESULTS: Eighty-one patients with clinical Stage IB-IVA carcinoma of the cervix were enrolled in this prospective, single arm, Phase I/II study. Hyperfractionated irradiation was completed in 88%. Brachytherapy was given in two implants in 46% and in one implant in 54%. Six patients had acute Grade 3 toxicities. The cumulative rate of Grade 3 and 4 late effects for patients with Stage IB2, IIA, and IIB disease was 7% at 3 years, 7% at 5 years, and 10% at 8 years. For patients with Stage III and IVA disease, the rate of late toxicities (Grades 3 and 4) was 7% at 3 years and 12% at 5 years. The site of first failure was in the pelvis in 41%, para-aortic or supraclavicular lymph nodes in 6%, and other distant metastatic sites in 14%. The absolute survival rate was 61% at 3 years, 48% at 5 years, and 45% at 8 years. The disease-free survival rate was 43% at 3 years, 38% at 5 years, and 33% at 8 years. CONCLUSION: The results suggest that, combined with brachytherapy, hyperfractionated irradiation to total parametrial doses about 10% greater than doses administered with standard fractionation pelvic irradiation was tolerated and at least appears to be as effective as standard fractionation pelvic irradiation.

Adolescent↗

PubMed2002

Forward planning using multileaf collimation as a replacement for patient tissue compensation.

In treatment planning, a dosimetrist may encounter a technique that would best be treated by including some type of compensation to correct for tissue or depth variations throughout the field, allowing for a more homogeneous dose distribution. Recent innovations, such as intensity-modulated radiotherapy (IMRT), have been introduced in an effort to address these issues. In many institutions, however, the treatment planning capabilities available may not accommodate consideration of such new technologies. The treatment planner is therefore left to determine how to incorporate these concepts with the current technologies available. While compensation may be an option, this may not always be possible due to the position of the beam or to actual mechanical restraints. Some institutions may also lack the ability and equipment to consider compensation at all. The answer is forward planning IMRT. This concept combines current forward planning techniques with multiple asymmetrically blocked treatment fields, varying the intensity of the beam from a given orientation to produce the desired treatment plan.

Humans↗

PubMed2002

Dose calculation errors due to inaccurate representation of heterogeneity correction obtained from computerized tomography.

Computerized tomography (CT) is used routinely in evaluating radiation therapy isodose plans. With the introduction of 3D algorithms such as the voxel raytrace, which determines inhomogeneity corrections from actual CT Hounsfield numbers, caution must be used when evaluating isodose calculations. Artifacts from contrast media and dental work, radiopaque markers placed by the treatment planner, and changing bowel and rectal air patterns all have the potential to introduce error into the calculation due to inaccurate assessment of high or low density. Radiopaque makers such as x-spot BB's or solder wire are placed externally on the patient. Barium contrast media introduced at the time of simulation may be necessary to visualize specific anatomical structures on the CT images. While these localization and visualization tools may be necessary, it is important to understand the effects they may introduce in the planning process. Other problems encountered are patient specific and out of the control of the treatment planner. These include high- and low-density streaking caused by dental work, which produce computational errors due to overestimation, and small bowel and rectal air, the patterns of which change on a daily basis and may result in underestimation of structure density. It is important for each treatment planner to have an understanding of how this potentially tainted CT information may be applied in dose calculations and the possible effects they may have. At our institution, the voxel raytrace calculation is automatically forced any time couch angle is introduced. Errors in the calculation from the above mentioned situations may be introduced if a heterogeneity correction is applied. Examples of potential calculation errors and the magnitude of each will be discussed. The methods used to minimize these errors and the possible solutions will also be evaluated.

Artifacts↗