348 I . J . Rad ia t ion O n c o l o g y • B io logy • Phys ics V o l u m e 42 , N u m b e r 1 S u p p l e m e n t , 1998

2241 TRANSCATHETER ENDOVASCULAR RADIATION THERAPY WITH LIQUID HOLMIUM-166 BALLOONING

IN PORCINE CORONARY ARTERY INJURY M O D E L

Young-Taek Oh, Han-Soo Kim*, Mison Chun, Jung-Sun Kim *, Seung Hee Kang, Haejin Kang, Chul-Woo Joh*', Young-Mi Kim ~, Kyung Bae Park ~ , Chan Hee Park'+

Department of Radiation Oncology, *Department of Cardiology, *Department of Histopathology and "+Department of Nuclear Medicine,

Ajou University School of Medicine, Suwon 742-449, Korea,

~Korean Atomic Energy Research Institute, Daejun 305-600, Korea

Purpose: Neointimal proliferation is the main process causing restenosis after coronary angioplasty and it is reduced with endovascular radiation

therapy. We tried to evaluate the effectiveness of transcatheter radiation therapy with a radioisotope, Holmium-166 (Ho-166) in porcine coronary

artery injury model.

Materials and Methods: Domestic pigs weighing 25-30kg tmderwent oversize injuries on the proximal portion of left anterior descending and/or

circumflex arteries. A randomly selected artery was irradiated by ballooning the catheter with liquid Ho-166. Ho-166 is a 94% beta-emitting isotope

(maximum energy: 1.84MeV). The balloon of the catheter was filled with Ho-166 for a time to irradiate 9Gy or 18Gy to the lmm depth from the

balloon surface. Four weeks later, pigs were sacrificed and coronary arteries were perfusion fixed. Maximal intimal thickness (MIT), intimal area (IA) and intimal area/fracture length (IA/FL) were measured by histomorphometric analysis.

Results: M1T was 0.48+0.13mm in control (N-13), 0.42+0.10mm in 9Gy group (N-7) and 0.14+0.11mm in 18Gy group (N=8). IA was

1.18+0.55mm" in control, 0.78+0.402 in 9Gy group and 0.29_+0.12mm ~' in 18Gy group. IA/FL was 0.47+0.25mm in control, 0.38_+0.19mm in 9Gy

group and 0.12_+0.16mm in 18Gy group. All parameters of neointimal proliferation (MIT, IA and IA/FL) were reduced in 9Gy and 18Gy group and

the reduction of MlT and IA were significant in 18Gy group compared with control and 9Gy group.

Conclusions: Transcatheter endovascular radiation therapy with liquid Ho-166 ballooning was effective for the prevention of neointimal proliferation in porcine coronary artery injury model. The reduction of neointima was more prominent in 18Gy group compared to 9Gy group.

2242 RADIATION THERAPY FOR WET TYPE AGE-RELATED MACULAR DEGENERATION: LONG TERM FOLLOW-UP RESULTS

Sasai, Keisuke, *Takahashi, Masayo, *Mandai, Michiko, *Ogura, Yuichiro, Hiraoka, Masahiro, and *Honda, Yoshihito Department of Radiology and Ophthalmology *, Kyoto University Hospital, Kyoto 606-8507, Japan.

Pu rpose /Ob jec t i ve : Choroidal neovascularization (CNV) is a major cause of severe loss of visual acuity in some ocular diseases such as age- related maeular degeneration (ARMD). The indication for laser photocoagulation therapy, which is one treatment modality for ARMD, is very limited, especially for occult type CNV. Recently, some investigators reported the effect of low dose irradiation for this abnormality. We also previously reported the early results of our phase I and II studies of radiation therapy for ARMD at the 38th ASTRO Annual Meeting. At that time we concluded that radiation therapy seemed to be useful in the treatment of CNV. The dose of 20 Gy in 10 fractions was more effective in treating neovascular membranes than the dose of 10 Gy in 5 fractions. However, the effectiveness of radiation therapy for this disease is still controversial. We report here, the long term follow-up results of our studies. Materials & Methods: Between April, 1994 and July, 1995, 33 patients with occult type CNV with or without the classical type of the wet type ARMD were treated with radiation therapy. However, 3 eyes were not evaluated in this study because 1 patient died of intercurrent disease, and 2 were lost for the follow-up after 12 months. The macula and optic disc received a dose of 10 Gy/5 fractions/l week or 20 Gy/10 fractions/2 weeks. Records of the 16 eyes with ARMD referred to our hospital in 1993, which satisfied the eligibility criteria for this study, were retrospectively analyzed for comparison. There was no significant difference among these 3 groups of patients in age, visual acuity or size of CNV of the affected eye at the start of the follow-up or the treatment. Fluorescein angiographie evaluation of the CNV and measurement of the best corrected visual acuity were performed 24-36 months after treatment. Results: There was no significant acute morbidity. Cataract formation after 1 year was observed in 1 patient. The visual acuity significantly decreased in all groups 24 months after treatment. However, at the end of the follow-up period, the number of eyes which showed visual acuity better than 0.1 was significantly higher in the 20 Gy irradiated group than in the control group (Table). Ten of 16 eyes in the control group showed a significant increase in size of CNV. Ten of 15 eyes in the 10 Gy irradiated group and I1 of 15 in 20 Gy irradiated group showed improved CNV after treatment. However, at the end of the follow-up period, only 5 and 7 eyes, respectively showed a decrease in the size of CNV (Table). C o n c l u s i o n s : This phase UII study including a dose escalation study sho,,;ced that radiation therapy seems to be useful for CNV during the first 12 months. Some eyes which initially showed good response to irradiation began to lose their visual acuity. However, the dose of 20 Gy in 10 fractions seemed useful to maintain the visual acuity better than 0.1 in this long term follow-up study. We have started a multi- center prospective randomized study to confirm the effectiveness of this treatment modality.

Table

Radiation dose Control 10 Gy 20 Gy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Number of eyes 16 15 15 Visual acuity

Improved 0 3 1 Unchanged 2 1 6 Deteriorated 14 11 8 * Better than 20/200 0 3 8**

Size of CNV Decreased 4 5 7 Unchanged 2 2 1 Increased 10 8 7

* 0.05<P<0.1 ** P<0.05