198

THE ROLE OF RADIOTHERAPY FOR BENIGN DISEASES: DEGENERATIVE AND HYPERTROPHIC DISORDERS.

M. Hdnrich Seegemcluuledt, Alfried Krupp-Krankenhaus Essen (Germany); Ludwig Keilholz, Universltlt Erlsngea-Edangen (Germany)

RIfi0n~e: The use of radin0w..rapy (RT) for benign disorders is still regarded wi~ disfavour today. Its use depends on common m~ner~ standards, referral prance, and persozal expertise oftbe r a d i o ~ i s L Possible risks and clinical results are controversially discussed in North Arnica and Europe. Former well-arx:epted indications have been abandoned for fear of ram tn~ancot sequelae and legal consequences, while in conU'ast some accepted clinical indications have been poody analyzed and backed up by ccotmlled clinical Oials in the past.

Methods: At our institution RT has been applied for pare relief in dsgea~e, ratJve joint disease (N = 103), peritcndinitis calearm of the shoulder (N = 89), epi- condylopathia humeri (N = 93) and plantar heel spur (N = 170); RT has been also used for prophyla~s of a~sease progression in hypertrophic disorders, i.e. the early stage Mot'bus Dupuytren (N = 142). For each rarity established subjective and objective scores (e.g. Shouldea': Ccostant-Score; Hip: Harris-Score; Knee: lnsall-Score; Morbtts Duputren : Score of Micho~Tubiana & Thoaune) were used to quantify the treatment outcome ia short and long-term foflow..up.

Results: A reduobon of pain symptoms was achieved in 64 of 103 treated painful joints. A complete and partial pain relief was achieved in 72 of 89 cases of pefitendinids calcatea, in 75 of 93 c~.ses ofepicondylopathia humeri and in 137 of 170 cases with paJnf~ plantar heel spu~. A total of 102 of 142 cases with M. Dupuy~en had an improvement of synkotoms and 126 of 142 eases remained flee of disease progression at last follow.up. All applied scores proved to be useful measures to evaluate the suczess of RT. The parameters most responsible for lack of success were the long dm'afioa of symptoms (> 12 months), the chronic pain type and slow onset of pain relief~ RT was less successful in more advanced stages of Morbus Dupuymm. The results corrmlxmd with many former clinical studies.

Condusion; RT is a very simple and cost-effective tream,,e~ in otherwise refractory degenerative disorders; in addifioo it can also p~vent progression in hypertrophic disorders. The applied sooting systeras should be prospectively applied to analyze the treatment outcome in future conu'olled clinical n-inls.

200

DOSE DETERMINATION FOR EYE MELANOMA TREATMENT

D. Firths, M. Bambynek, M. Heintz, U. Quast, H. Kolanoski Universit~itsklinikum Essen, Universi~t Dortmund, Humboldt- Universit/it zu Berlin - Germany

P u r n o s e . Method and Materials; The successful brachytherapy treatment of intrancular tumors requires an exact knowledge of the spatial dose distribution of the eye plaque relative to the tumor and rarliosensitive structures. To achieve this accuracy we used high precision dosimetry based on plastic scintillators and numerical simulations of the physical particle interactions. Scintillators are suitable for a fast and accurate dosimetry of 1251- and 1°6Ru/~°~da- plaques because of a high spatial resolution, a large dynamic range and an atomic composition close to that of water. We constructed a special phantom with 16 scintillation dosimeters with simultaneous read out. For the numerical simulations of the physical parameters we developed a Monte Carlo program and analyzed the measured results in detail. Furthermore, systematical simulations of plaque design were performed to prepare measurements.

Resu l t s and Conclusion: Eye plaque dosimelry with plastic scintillators has proven its applicability for the clinical routine and research. We found an excellent agreement between the measurements and Monte Carlo calculations. We analyzed the influence of backscatter and penumbra effects and successfully introduced a new type of optimized 12SI-applicator into clinical routine. The effect of fluorescent x rays on the dose distribution is now going to be determined. In future, the scintillation dosimetry in combination with improved methods of localization will set a standard of physical therapy planning and quality control comparable to other fields of radiation therapy.

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199

• D O S E A N D V O L U M E S P E C I F I C A T I O N F O R R E P O R T I N G I N T E R S T I T I A L T H E R A P Y ~ , I C R U R E C O M M E N D A T I O N

A n d r 6 e Dutreix University Hespital, Gasthuisherg, lamven, Belgium

The ICRU Report on Dose and Volume Specification for Reporting Interstitial Therapy, has been finally approved by the ICRU main Commission. The recommendations cover the following items :

- description of the gross tumour and clinical target volnme,

- description of the sources, the implant technique and source pattern

- description of time pattern, and dose rates - Total Reference Air Ke~na (TRAK), - description of dose and dose distribution, including high

and low doseregions, uniformity parameters and alternative methods The dose description includes prescribed dose, mean cenmtl dose and peripheral dose. A clear def'mition of the "mean central dose" is given with the description of three possible methods of evaluation. Definition of time pattern cover the new modalifies like pulsed irradiation. List of items to report with priorities, depending on the one hand on the type of technique used and on the otbea" hand on the level of computation available, are given for the different kinds of applications. Finally the report includes several examples of implants with the quantifies to be reported.

201

NEW RADIONUCLIDES FOR BRACHYTHERAPY APPLICATIONS.

RAVINDER NATH, Yale Univ. School of Medicine, Dept. of Therapeutic Radiology, New Haven, Connecticut, USA.

Brachytherapy is now an integral part of radiation treatment for the management of cancers of several sites, including the head and neck, uterine cervix, endometrium, and prostate. Recently, intravascular brachytherapy is presenting a new treatment option for atherosclerosis in the cardiovascular system by reducing restenosis after angioplasty in both the peripheral and coronary arteries. Physical advantages of brachytherapy result from a superior localization of dose to tumor volume. There are two different forms of brachytherapy: intracavitary irradiation using radioactive sources placed in body cavities in close proximity to the tumor;, and interstitial brachytherapy using radioactive seeds implanted directly into tumor volume. Intracavitary radiation is always temporary and usually takes about one to four days. Interstitial brachytherapy can be temporary or permanent. Radioactive sources emitting higher energy photons have better tissue penetration but are more difficult to shield for radiation protection purposes than sources emitting lower energy photons. Longer-rived radioactive sources can be used several times in different patients, which w.duces their effective cost compared to shorter lived radioisotopes. However, for permanent implants, sborter-lived radionuclides can provide higher initial dose rate, which may have biological advantages in some cases. These characteristics of various forms of brachytberapy dictate the choice of radioactive sources for a specific treatment. Recently, a number of new radionuclide sources have been developed, making a wide variety of half lives and photon energies available to the brachytherapy community. Conventional sources for brachytherapy in the United States are cesium-137, iridium-J92, iodine-125 and gold-198. The physical chara-'teristics of these sources and of the newly developed sources, americium-241, palladium-103, samarium- 145, ytterbium- 169 and intravascular brachytherapy sources ate described.