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Journal of Cancer Research and Therapeutics, Vol. 1, No. 2, April-June, 2005, pp. 73-74 Invited Editorial Brachytherapy - Perspectives in evolution: Take it with a bag of salt... Shrivastava Shyam Department of Radiation Oncology, Tata Memorial Hospital,
Parel, Mumbai - 400 012 Code Number: cr05015 Marie and Pierre Curie discovered ′radium′ in their laboratory in Paris in 1898, to which the discipline of brachytherapy owes its existence today. Soon after its discovery, the biological effects of radium were beginning to be observed and understood giving rise to the belief of its potential therapeutic virtues. [1],[2] The first clinical use of radium was reported by Dr. Danlos[3] in 1901, who successfully treated a few cases of lupus with an admixture of radium and barium chloride. Simultaneously several other investigator, on both sides of the Atlantic explored its use in chronic inflammatory skin diseases viz. lichen, eczema, psoriasis, naevus and dermatitis. The first successful brachytherapy application for malignancy was carried out at St. Petersburg in 1903 for basal cell carcinoma of the facial skin, prompting its widespread use for skin cancers in Europe. The advent of endocavitary treatment in 1904 for uterine and cervical cancers truly opened a board field of applications in brachytherapy.[4] The next few decades were witness to the development and continuous refinements in applicator design and dosimetry methods. Although brachytherapy dosimetry was first initiated around 1904, the calculations regarding the amount of radium and the duration of application were largely empirical till the 1930s, until Paterson and Parker [5] published their seminal work on radium dose distributions. In 1934, a didactic system of brachytherapy the ′Manchester System′ was published [6] and has since been used as an indispensable basis of radium therapy. The ′Paris System′ proposed by Pierquin and Dutreix [7] which predicts the constant relationship between dimensions of the implanted volume and isodose lines has been the benchmark for interstitial brachytherapy. The 1950s-60s witnessed rapid developments in external beam radiotherapy. The advent of megavoltage teletherapy equipment computerized treatment planning and dosimetry methods, coupled with the disadvantages of radium - bulk, rigidity, radiation hazards - forced brachytherapy to the backstage temporarily. The introduction of artificially produced radioactive isotopes gave a new dimension leading to the renaissance of brachytherapy. Newer radionuclide such as Co 60 , Cs 137 , Au 198 and I 131 that could be used as radium substitutes were rapidly introduced in the clinic. Others such as Pd 103 , Sm 145 , and Yt 169 were hailed as isotopes of the future.[8] Perhaps the most revolutionary step in brachytherapy was the development of ′stepping source dosimetry system′using a single miniature Ir 192 source.[9] The use of single high activity source dispensed the need for extensive inventories typical of multiple sources. Advanced imaging, 3-dimensional reconstruction algorithms, sophisticated optimization tools and inverse planning modules have all revolutionized modern brachytherapy allowing accurate radiation dose delivery to the target with minimal dose of surrounding normal critical tissues - the highest form of conformality. The evolution of brachytherapy at Tata Memorial Hospital (TMH) has been commensurate with the developed world.[10] In 1941, when the hospital was founded, it had its own Radon plant. The brachytherapy was set-up by Dr. Naidu, an eminent physicist, who was trained by Curies and worked at Memorial Sloan Kettering Cancer Centre, New York. The hospital first procured pre-loaded Co 60 and Cs 137 capsules in the sixties for use in brachytherapy. In 1962, radioactive Gold grains were first used for permanent implants. The afterloading era began in 1972 when Co 60 sources were used to manually afterloading implants. Cs 137 tubes, from BARC in 1976 and Amersham in 1979 were subsequently used for manual afterloading. Manual afterloading Cs 137 sources for gynecological brachytherapy. The Ir 192 sources for interstitial implant were first introduced in India at the TMH in 1981. The first remote afterloading system was procured in 1985. Since 1994, the high-dose rate remote afterloading system has been operational and is responsible for resurged interest in brachytherapy. It is a very versatile tool in the hands of the radiation oncologist with access to virtually any site in the body. Recently, the centre has commissioned an Integrated Brachytherapy Unit (IBU) at its new research facility at ACTREC. The CT/MRI compatible applicators will be useful in image-guided brachytherapy. Further developments in radiation physics, radiobiology and cancer biology have prompted mathematical modeling of radiation effects and iso-effect conversions from low-does rate system to high-dose rate brachytherapy. Despite the technological improvements, the use of imaging in brachytherapy has been limited mostly to kilovoltage x-rays (orthogonal films) and has lagged behind the phenomenal advances in teletherapy imaging, planning, verification and delivery. The 3D-CRT, IMRT, IGRT etc. will force brachytherapy to pass through the acid test of tumor control and normal tissue complications.[11] Certainly the brachytherapy is a quicker mode of treatment compared to competitive procedures and should not be lost in the bewilderedness and market driven technological advances as happened in sixties and seventies. All modalities should be welcomed as a part of large armamentarium from which the patients and clinicians can tailor treatment to the individual′s tumor, physical condition, medical status and psychological well being. The incorporation of better quality imaging such as CT/MRI in the brachytherapy suite may serve as a catalyst to popularize image-guided brachytherapy. Newer applications such as thermo-brachytherapy and brachy-robotics are currently under investigation and may change the face of brachytherapy in the future. This is evident that in the newer advances, computers have played a major role in development and therefore brachytherapy planning and dose control optimization should not be left behind and thus run parallel to external beam radiation development as both are complementary to each other. References
Copyright 2005 - Journal of Cancer Research and Therapeutics |
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