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ABSTRACT: Skin toxicity is a ubiquitous side effect in radiotherapy and can be difficult to predict. Moist desquamation in cancer patients can decrease quality of life and occasionally demand unplanned treatment breaks thus worsening outcome. In breast cancer patients, moist desquamation occurs approximately one-third of the time, and while avenues such as intensity-modulated radiation therapy exist to decrease skin side effects, they may be prohibitively expensive to distribute widely. To selectively target patients who are at risk for high skin toxicity, toxicity prediction beyond heuristics is required. This study presents 3D thermal tomography, a translation technology that employs active thermal imaging to map the thermal effusivity of skin. Irradiated mice were imaged throughout reaction development to establish a correlation between effusivity changes and eventual toxicity severity. Female hairless mice (n = 11) were anesthetized and irradiated to 40 Gy in one fraction using a 1 cm Leipzig brachytherapy applicator with an Ir-192 source. After irradiation, thermal imaging was conducted daily with a flash lamp and infrared camera. Effusivity was calculated using custom software and tracked within irradiated and contralateral control regions. Mice were retrospectively grouped into high-grade (moist desquamation present, n = 6) and low-grade (n = 5). All mice showed an increase in the relative average effusivity difference among the treated and control regions between irradiation and peak reaction between 12 and 15 days after irradiation. The high-grade group showed an earlier increase in relative average effusivity difference (mean 1.7 days after irradiation versus 4.4 days after irradiation) than the low-grade group, and had a significantly greater relative average effusivity difference between 2-5 days after irradiation. We concluded that 3D thermal tomography is quick, non-invasive, non-ionizing and exhibited a correlative difference between mice that eventually developed moist desquamation and those that only presented dry desquamation. With further development, it may prove to be a useful tool in the clinic for differentiating patients who require preventative measures to reduce skin toxicity.
Radiation Research 07/2012; 178(4):295-303. · 2.68 Impact Factor
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ABSTRACT: Static field intensity modulated radiation therapy (IMRT) has demonstrated dosimetric and clinical benefits over 3-dimensional conformal radiation therapy. TomoTherapy is a unique form of IMRT that may offer further improvements.
The study population consisted of 15 patients with low-risk prostate cancer treated at Rush University with TomoTherapy (n = 7) or IMRT (n = 8). For each patient, both a TomoTherapy plan and an IMRT plan were generated using identical planning objectives. The planning target volume (PTV) was defined as the prostate and proximal seminal vesicles plus a margin. The prescription dose was 7740 cGy in 43 fractions. Radiation Therapy Oncology Group (RTOG) normal tissue guidelines were used as constraints, and the PTV coverage was made equivalent for the paired plans by equalizing the PTV V100. RTOG benchmark DVH values for the rectum and bladder and mean dose to the penile bulb were recorded. The volume of PTV receiving ≥ 105% of the prescription dose was measured.
The mean DVH values for each of the RTOG constraints for rectum and bladder were significantly improved using TomoTherapy. The volume of the PTV that received at least 105% of the dose was higher with IMRT (11.7% vs. 0.2%, <0.001). The mean dose to the penile bulb was higher with TomoTherapy (40.4 Gy vs. 27.4 Gy, P = 0.005).
TomoTherapy offers a more favorable dose distribution to the bladder and rectum, as well as improved target homogeneity in comparison with IMRT.
American journal of clinical oncology 07/2009; 32(5):460-6. · 2.21 Impact Factor
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ABSTRACT: This analysis was undertaken to dosimetrically compare iridium-192 high-dose-rate brachytherapy (IB) and Xoft Axxent Electronic Brachytherapy (XB; Xoft Inc., Sunnyvale, CA) in the treatment of endometrial cancer.
The planning CT scans from 11 patients previously treated with IB were used to construct hypothetical treatment plans using the source characteristics of the XB device. The mean V95, V100, and V150 (percent of the planning target volume that received 95%, 100%, and 150% of the prescription dose) were calculated. For both the bladder and rectum, the V35 (percent of the organ that received 35% of the prescription dose) and V50 (percent of the organ that received 50% of the prescription dose) were calculated for each patient using both methods of vaginal brachytherapy.
The mean %V95 was 99.7% vs. 99.6% (p = ns) and the mean %V100 was 99.0% vs. 99.1% (p = ns) for the IB and XB methods, respectively. The mean %V150 was 35.8% vs. 58.9% (p < 0.05) for the IB and XB methods, respectively. The mean bladder %V35 was 47.7% vs. 27.4% (p < 0.05) and the mean bladder %V50 was 26.5% vs. 15.9% (p < 0.05) for the IB and XB methods, respectively. The mean rectal %V35 was 48.3% vs. 28.3% (p < 0.05) and the mean rectal %V50 was 27.8% vs. 17.0% (p < 0.05) for the IB and XB methods, respectively.
The IB and XB methods of vaginal brachytherapy offer equivalent target volume coverage; however, the XB method allows increased sparing of the bladder and rectum.
Brachytherapy 10/2008; 7(4):351-4. · 1.47 Impact Factor
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ABSTRACT: A new form of partial breast irradiation (PBI), ClearPath (CP) breast brachytherapy, has been introduced. We present our results of a dosimetric comparison of MammoSite (MS) and CP PBI.
The dimensions of the CP device were reconstructed onto the MS planning CT scans for 15 previously treated patients. The mean %V(100), %V(150), %V(200) (percent of the PTV that received 100%, 150%, and 200% of the prescription dose, respectively), ipsilateral breast %V(50) (percent of the ipsilateral normal breast that received 50% of the prescription dose), ipsilateral lung %V(30) (percent of the ipsilateral lung that received 30% of the prescription dose), the heart %V(5) (percent of the heart that received 5% of the prescription dose), and the maximum skin point dose per fraction were then determined for each patient using the two methods of balloon-based PBI.
The mean %V(100) was 96.5% vs. 96.5%, the mean %V(150) was 42.1% vs. 42.9% (p=ns), and the mean V(200) was 11.4% vs. 15.2% (p<.05) for the MS and CP methods, respectively. The mean ipsilateral breast %V(50) was 19.8% vs.18.0% (p<.05), the mean ipsilateral lung %V(30) was 3.7% vs. 2.8% (p<.05), the mean heart %V(5) was 57.0% vs. 54.3% (p<.05), and the maximum skin point dose per fraction was 312.2 and 273.6cGy (p<.05) for the MS and CP methods, respectively.
The MS and CP methods of PBI offer comparable target volume coverage; however, the CP device achieves increased normal tissue sparing.
Brachytherapy 10/2008; 8(1):14-8. · 1.47 Impact Factor
