Obermedizinalrat Dr. med. univ. Ferdinand SILBERBAUER

Radiosensitizing by heavy atoms –

Approach to a new more efficient radiation therapy


keywords: Radiosensitizing by heavy atoms; enhancement of focal dose by heavy atoms


 In this report the beginning of a new, more effective kind of high voltage therapy is shown, while as much heavy atoms as possible are selectively brought into a malignoma, which liberate much more energy in the tumour, as it otherwise may be the case. A great part of the radiation energy, what would simply penetrate the tumor without damaging it, is forced by the heavy atoms to get free selectively in the tumor. As more electrons, according to the ordinal number of the heavy atoms, are existing in the coat of an atom, and as more of these heavy atoms are included in a tumor, as more additional energy is liberated in the tumor in the high voltage therapy. This circumstance leads to healings, where they wouldn't be possible in other case, and promises for the future to need only half of the now usual radiation dose and to achieve healings with an on certainty bordering probability.


 In this report will be explained, why heavy atoms, which are incorporated in a tumour, induce an enhanced focal dose in the radiation therapy: by the enrichment of heavy atoms in a tumor (iodine, gold, gadolinium or platinum) is caused here during a high voltage irradiation an enhanced formation of positrons and electrons. Conditioned through that, by the mutual deletion of positron and electron the so-called extermination - radiation with the energy of 0,511 MeV is created. This extermination - radiation causes now in the tumor the Compton - photo - complex - reactions, which take place in a very small area (within millimeters) closely related to the heavy atoms,  i.e., at an high - energy – Compton - effect with an heavy atom a shower of  electrons, which damages the tumour, is released, and the resulting low energetic Compton - scattered - radiation is absorbed by a light atom ( f.i. oxygen, carbon, nitrogen) within a mean distance of 2mm off the heavy atom by means of a photo- effect, what also damages the tumour. In addition the middle energetic Compton - scattered - radiation (around 100 KeV) from the surrounding tissue is absorbed by photo- effects with high incidence proportional to the fourth potency of the effective ordinal number of the tumour in the heavy - atom - loaded tumour tissue. Moderately heavy atoms, like iron or zinc, if they are accumulated in the tumour, they induce an increased photo - absorption of the middle and low energetic Compton - scattered - radiation from the tissue surrounding the tumour.  

Now in the high voltage therapy the effects of the heavy atoms in a tumour are first theoretically and then by concrete instances discussed. Already some tens of years ago in the radiation physics [1, 2] the basis of this new start of radiation therapy has been explored, what has the aim to incorporate as much as possible heavy atoms selectively into a malignoma. Heavy atoms have the ability to take much more energy out of high voltage photons by high energetic Compton effects [1, 2], as what it is possible by light atoms. In this case many electrons are released all at once out of a heavy atom, by what a considerable part of energy of a high voltage photon is consumed [1, 2]. These released electrons release yet secondary and tertiary electrons [2] and disturb and change the biochemical bindings of the chromosomes, by what the death of the cells is caused. The remaining Compton - scattered - photons are mainly absorbed by means of photo - absorption [1, 2], by what also electrons are released, which operate destroying in the tumour. Worthy readers, please save me from quoting mathematical formulas for the expected effects! I found 1989 [6] mathematical nearings, which showed, that the probability of electron - pair - formation [1, 2], Compton effects and photoelectric effects in the case of incorporation of heavy atoms into a tumour is increased and that the enhancement, which is achieved in the CT, can be employed for the calculation of the expected focal dose [6].But it is difficult to introduce energetic levels from 1 MeV up to 25 MeV stepwise into a mathematical formula. Just so difficult is the introduction of secondary and tertiary electrons into this formula. Also the ordinal number of the employed heavy atoms plays a bigger role as expected [3,4,10,11,12,13]. In the future we should let us guide by empiricism. In the reality the effects seem to be much stronger than these by me at that time calculated [ 3,4,5,8,10,11,12,13].

 When during high energetic Compton - effects low energetic Compton - scattered - photons are released and within a mean radius of two millimetres are absorbed again, so it is possible to call these proceedings as a Compton - photo - complex - reaction [6].

 By these Compton - photo - complex - reactions in the low voltage range 25 years ago a nine year old boy, who was suffering from an inoperable astrocytoma IV in the brain stem, was cured. By erosion haemorrhages an accumulation of iron pigment had occurred in the 20 millimetres measuring tumour, what was visible in the CT. The radiation therapy with cobalt 60, caused by me, leaded with a focal dose of only 50Gy to a complete deletion of the tumour. Ten years after the radiation therapy the young man was completely rehabilitated. Similar effects every time could be obtained by contrast medium assisted radiation therapy, contrast medium, as it is used at the CCT, to cure patients with an astrocytoma, meningeoma or neurinoma or metastases of malignomas in the brain [10,11,12,13]. These tumours namely show at the CCT an enhancement till 20 Hounsfield - units, what is caused by the iodine atoms.  

Imagine, from astrocytoma IV suffering absolute death - candidates could be cured already tomorrow by administering the contrast medium 30 to 60 minutes before the irradiation with a contrast medium - dose like at the CCT and in that time - window, in which the enhancement is already weakly visible [10,11,12,13]. Focal dose: 20 to 30 Gy in 4 to 6 fractions, each 5 Gy [10].

 This assertion is confirmed by tasks from USA [3, 4] with a great number of patients, which tell about radiosensitizing by bromodeoxyuridine (BDU) and jododeoxyuridine (JDU). Iodine in the JDU is distinct heavier than bromine in the BDU. Iodine has in its atom - coat 53 electrons, bromine only 35 [1]. Iodine therefore can deliver more electrons, when a high - voltage – photon "strikes" [1]. Although JDU and BDU biochemically behave identically, it comes in the astrocytoma IV with JDU as a radiosensitizer to a two - year - surviving - quota of 68%, with BDU only of 28%. But it must be considered, that with these substances an enhancement at the CT not yet is discernable. Therefore a focal dose of 60Gy is needed still for these effects. In the Nose - Ear and Throat - field there was Cisplatinum used as a radiosensitizer for advanced head and neck - cancers [5] and a two year - surviving - quota of 53% and a five - year - surviving - quota of 32% achieved. Platinum has 78 electrons in its atom - coat and leads therefore to these astonishing results.



But with an iodine - caused just yet visible enhancement (time window!) of an astrocytoma IV you will come out with a distinct smaller focal dose, while a complete deletion of the tumour is obtained [10, 11, 12, 13]. Professor Pfab in Marburg on the Lahn in Germany achieved at a cavernous gigantic haemangioma [8] in the head - and - neck - field by a focal dose of only 18 Gy with hard photons of 10 MeV a complete disappearance of the tumour. In Lissabon were cavernous haemangiomas of the liver stopped with telecobalt by a focal dose of only 20 to 30 Gy [9]. These results were achieved by iron, which exists as middle - heavy atom with the ordinal number 26 abundant in the red blood cells of the streaming blood by high energetic Compton - effects. The electrons damage the vascular wall, before they are captured again by the iron - atoms, what guides to disappearance of the haemangioma or at least to a stop of its growth.

You see, a higher energy level of the photons leads earlier to a disappearance of the tumour, when heavy atoms are used as a radiosensitizer, as heavier the atoms, as better the results. In the last two years were by Gadolinium - Tex, a new magnetic contrast medium and radiosensitizer [11,12,13], numerous various cancers by MRI explored and then by a focal dose of only 30 Gy insolated. In the occurred excellent results has gadolinium with the ordinal number 64 decisive participated.

The radiation therapy is here performed in a time - window between two and four hours after the intravenous injection, because the malignoma is here selectively enriched with gadolinium. In this case the tumour is deleted without considerable damage of the normal tissue [12, 13]. The results could be considerable improved, if a linear accelerator of 6 to 10 MeV would be used [8, 9].It would be possible to come out with a focal dose of 15 Gy, only the fourth part of the now usual focal dose, which deletes yet the tumour. 

At the radiation therapy in the head - and - neck - field the following problem occurs:  when the focal dose of the high voltage therapy becomes bigger than 30Gy, so arises with increasing dose a painful mucositis [7] and gradual also an atrophy of the salivary glands. Similar results you find in other fields, where radiation therapy is used.

 C o n c l u s i o n

 In the future it will be necessary to use such a successful radiosensitizer, which obtains with a focal dose of only 30 Gy the secure deletion of the tumour cells. This demand I want to extend on all tumours, which are treated by radiation therapy.

I think that it will come to progresses in this direction by this report.


I thank Mrs. Dr. Brigitte Kaik for helps in English language.

Also Mrs. Webernig Sabine, Webernig Alexander - Ingo and Mr. Waldbauer Guenther for helps in manuscript preparation.

Many thanks to Mr. Schlögl Reinhold and all friends, who send me very good literature.

R e f e r e n c e s

 1. Gerthsen-Kneser-Vogel, PHYSIK, Springer Verlag

 2. Theodor Laubenberger, Leitfaden der medizinischen Röntgentechnik, Diagnostik, Dosimetrie, Strahlenschutz, Strahlentherapie; Deutscher Ärzteverlag

 3. C. Urtasun, D. Cosmatos, J. DelRowe, T.J Kinsella, S. Lester, T. Wasserman, and D.S. Fulton; Jododeoxyuridine (IUdR) combined with radiation in the treatment of malignant glioma: a comparison of short versus long intravenous dose schedules (RTOG 86-12)

 4. H.S. Greenberg, W.F. Chandler, W.D. Emsminger, H. Sandler, L.Junck, M.A. Page, D.Crane, P. Mc Keever, R.Tankanow and J. Bromberg; Radiosensitisation with carotid intra-arterial bromodeoxyuridine + 5-fluoruracil biomodulation for malignant gliomas; NEUROLOGY, September 1994 441715

 5. Prakash B. Chougule, Steve Suk, Quyen D. Chu, Louis Leone, Peter T. Nigri, Robert McRea, Mary Lekas, Anthony Barone, Dinesh Bhat and Josef Bellino; Cisplatin as a Radiation Sensitizer in the Treartment of Advanced Head and Neck Cancers.; CANCER, Vol. 74, No 7, October 1, 1994

 6. F. Silberbauer; Strahlentherapie mit erhöhter Wirksamkeit, RADIOLOGE (1989) 29:48-49

 7. Doz. Dr. M. Grasl, Univ.Klinik f. HNO-Krankheiten Wien; Schleimhaut-Irritationen bei Bestrahlung und Chemotherapie im HNO-Bereich; Published only, 1995, Vienna

 8. H. Proske, R.Pfab; Indikationsstellung zur Hochvoltbestrahlung kavernöser Riesenhämangiome, eine eindrucksvolle Kasuistik; DIE MEDIZINISCHE WELT 1993; 44:276-8 

 9. L.Gaspar, F. Mascarenhas, M. Sa da Costa, J. Schaller Dias, J. Gamma Alfonso, M.E. Silvestre; Radiation therapy in the unresectable cavernous hemangioma of the liver; RADIOTHERAPY AND ONCOLOGY 29 (1993) 45-50 

10. K.S. Iwamoto, A. Norman, D.B. Freshwater, M. Ingram and R.G. Skillan; Diagnosis and treatment of spontaneous canine brain tumours with a CT scanner; RADIOTHERAPY AND ONCOLOGY 26 (1993) 76-78 

11. Stuart W. Young, Fan Qing, Anthony Harryman, Jonathan L. Sessler, William C. Dow, Tarak D. Mody, Gregory W. Hemmy, Yunpeng Hao, and Richard H. Miller,; Gadolinium (III) Texaphyrin: A tumour selective radiation sensitizer that is detectable by MRI; Proc.Natl.Acad. Sci. USA, Vol. 93, PP. 6610-6615, June 1996, Medical Sciences 

12. DI Rosenthal, C. Becerra, E. Frenkel, P. Nurenberg, D. Carbone, S. Young, R. Miller, J. Engel, M. Holm, M.F. Renschler; Phase I single dose trial of the radiation sensitizer Gadolinium-Texaphyrin confirms tumour selectivity; Published Only, AACR/ASCO Meeting 1997 

13. P. Carde, DI Rosenthal, C. Koprowsky, R. Schea, J. Ruckle, R. Tishler, S. Qoung, R. Miller, M. Holm, M.F. Renschler; A Phase IB/II multi-dose trial of gadoliniumtexaphyrin as a radiosensitizer in patients with brain metastases: preliminary results.; Tuesday May 20, 1997, Poster discussion Session: Head and Neck and Central Nervous System Tumours ( A 108-112) AACR/ASCO Meeting 1997