- Email: [email protected]
Peaking Into the Future With Proton Therapy
Peaking Into the Future With Proton Therapy j Beverly Riley, CMD ABSTRACT: This article serves to provide a basic overview into proton radiotherapy. This shall give a brief description of proton therapy history, its uses, and differences compared to traditional photon radiation therapy in addition to some specific aspects of M. D. Anderson Proton Therapy Center. (J Radiol Nurs 2007;26:115-120.)
SO, WHAT ARE PROTONS ANYWAY AND HOW ARE THEY USED FOR CANCER TREATMENTS? The center of every atom has protons and neutrons that compose the nucleus. The nucleus of the atom is surrounded by electrons (Figure 1). The protons must be made into a form that is useful for cancer treatments. Only accelerators can produce protons with a sufficient enough intensity for therapeutic use (Breuer & Smit, 2000). There are two different types of accelerators that are used for clinical treatment, a cyclotron or a synchrotron. Cyclotrons are linear accelerators that produce a fixed energy, typically a higher energy of about 250 MeV. A synchrotron is a similar machine but has the ability to produce varied energies, usually in the range of 70e250 MeV. Protons are positively charged particles obtained by a hydrogen atom being injected into an electrical field where it is separated into protons and electrons. The protons are sent through a vacuum tube into the linear accelerator and the proton’s energy is boosted to about 7 MV. When the proton beam enters the synchrotron (this is what we have at M. D. Anderson Proton Therapy Center), it is accelerated to reach energies ranging from 70 to 250 MeV, and this is enough energy to place the protons at any depth within the patient’s body. The beam is then passed through a series of magnets which shape, focus, and direct the beam to the individual
Beverly Riley, CMD, is with M. D. Anderson Proton Therapy Center, Houston, TX 77054, USA. Address reprint requests to Beverly Riley, M. D. Anderson Proton Therapy Center, 1840 Old Spanish Trail, Houston, TX 77054, USA. E-mail: [email protected] 1546-0843/$32.00 Copyright Ó 2007 by the American Radiological Nurses Association. doi: 10.1016/j.jradnu.2007.09.001
VOLUME 26 ISSUE 4
treatment rooms. The individual Bragg peaks generated are too narrow to use for treatment, therefore the Bragg peaks are summed up and spread out (SOBP) to a useful plateau (Figure 3). PROTON THERAPY: HISTORICAL BACKGROUND Proton therapy has been used for cancer treatment since 1940s. In 1946, Robert Wilson, ‘‘The Father of Proton Therapy’’ suggested that protons might have a role in cancer treatment because of their advantageous dose distributions. Proton beam range is characterized by dose that rises sharply to a peak and then falls to zero at the end of the range; the shallow region, entrance area displays a relatively low dose (Figure 2). Wilson also proposed the use of range modulator wheels. This allows for the pristine Bragg peaks to be spread out (SOBP) to a more useful width to cover larger tumors (Figure 3). E. O. Lawrence won the Nobel Prize in 1939 for his contributions to the development of the cyclotron at the University of California Lawrence Berkeley Laboratory (LBL). C. A. Tobias, J. H. Lawrence and others were the first to actually use proton beams for treatment on human patients. These treatments were carried out at LBL in the 1950s on the 184-inch cyclotron. Proton therapy treatments continued on this cyclotron until 1992. Much work in proton therapy across the world continued to develop from the 1960s throughout the 1990s. Uppsala, Sweden developed radiosurgery techniques for the treatment of brain tumors and they became the first to use range modulation to achieve an SOBP to conform the dose along the beam path. Dr. Ray Kjellberg of Massachusetts General Hospital began treating small intracranial lesions in 1961 at the
www.radiologynursing.org
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Riley
Proton Therapy
JOURNAL OF RADIOLOGY NURSING 1.2
Relative Dose
1 0.8 0.6 0.4 0.2 0
6
7
8
9
10
11
12
13
14
15
Depth
Figure 3. Expanded Bragg peak.
Figure 1. Structure of an otom with its subatomic particles. (Courtesy of M. D. Anderson Cancer Center).
Harvard Cyclotron Laboratory in Cambridge, MA and many of the techniques developed there are still used today at The Frances H. Burr Proton Therapy Center in Boston, MA. Between 1968 and 1975, Russia was extremely active with proton therapy at The Joint Institute for Nuclear Research in Dubna and the Moscow Institute for Theoretical and Experimental Physics. Chiba, in Japan, later in the 1970s started treatment at the National Institute for Radiological Sciences. Clatterbridge, England, and Nice and Orsay, France both started programs as well as iThemba Labs in Cape Town, Africa, National Cancer Center in Kashiwa, Japan, and Dubna, Russia. Loma Linda University Medical Center was the first hospital-based proton therapy center located in Loma Linda, CA and began treating patients in 1990. This
was the first facility to have rotating gantries which enable treating from any angle much like a modern linear accelerator. Their facility has treated the most number of patients of all proton therapy centers to date. In the most recent years, three more proton centers have been opened in the United States, The Midwest Proton Center in Bloomington, IN, M. D. Anderson Proton Therapy Center in Houston, TX (PTCH), and The Florida Proton Therapy Institute in Jacksonville, FL. Most proton facilities have a fixed beam room which means that only the table moves in addition to having several rotating gantries. M. D. Anderson’s Proton Therapy Center is currently the largest in the nation. There is great desire for these centers to collaborate on patient protocols. A challenge to this lies in the fact that there are no ‘‘set standards’’ or class solutions for proton therapy treatment planning just yet as there is with traditional photon therapy. What this means is that not all plans are designed in the same fashion. There are various ways to achieve treatment plans. But for the protocol to have consistency, it is necessary for facilities to follow more stringent guidelines to aid in more measurable results. However, at M. D. Anderson Proton Therapy Center, every patient is on an in-house protocol. These data will be reviewed retrospectively in the future once a sufficient number of patients have been treated to collect enough data. WHAT MAKES PROTON THERAPY DIFFERENT?
Figure 2. Examples of a depth dose distribution for photons and protons.
116
Proton therapy differs from traditional radiation therapy in that protons have the unique ability to stop at a defined distance, or range. Proton beams enter the body and deposit most of their energy in the tumor region and then stop. The X-ray beams, used in traditional radiation therapy, traverse healthy tissue as well as the tumor and have what is known as exit dose (Figure 4). Although the doses that are given to the normal healthy tissues are within the acceptable dose limits, proton therapy has the ability to decrease
www.radiologynursing.org
DECEMBER 2007
Proton Therapy
JOURNAL OF RADIOLOGY NURSING
Riley
that for traditional photon radiation treatments, the dependence of the materials being traversed by the beam is much less sensitive to the various changes in material composition compared to protons. Proton beams are very sensitive to density changes, and the treatment delivery may be compromised if day-to-day setup is not precise. Therefore, daily imaging is required. IMAGE-GUIDED RADIATION THERAPY
Figure 4. Photon beam displaying exit dose. Proton beam displaying how dose stops.
the dose to these areas. Having the ability to decrease the dose to normal healthy tissue while focusing the dose on the tumor lends itself to the opportunity of increasing dose to the target area. Many types of cancers may have better local control if we have the ability to increase the total dose delivered to the tumor and spare the surrounding normal structures that have historically limited the dose that may be given to the tumor (Webb, 1993). For the most part, proton therapy is basically no different for the patients except for just a few things. All patients must first receive a simulation to receive any type of radiation therapy; this means the patient is to have a treatment planning CT scan. The patients are immobilized based on the area of treatment. Immobilization varies by the body part being treated in that more restrictive devices may be used for areas that tend to move more easily such as the head region. It is of utmost importance that the patients be set up each day in the exact same position with respect to the simulation using the same devices. This allows for the most accurate treatment delivery because the treatment plans generated are done so by using the CT data obtained during simulation. The main difference here is VOLUME 26 ISSUE 4
Image guidance to assist in daily setup for radiation therapy treatments is of great interest at this time. Historically, this has been used in proton therapy because of the precision required for particle therapy. Proper alignment of the target area could only be achieved this way. Today, 2 kV X-ray images are obtained before the treatment delivery to aid in setup. For example, to treat a prostate patient, each day the radiation therapist will take an image from the anterior-posterior projection (AP) and one from the left or right lateral position. These images are then aligned to the treatment planning images created from the simulation data using a sophisticated imaging alignment system. These images are coregistered to one another using identifiable anatomical landmarks. The AP image provides data needed to move the patient in the superior-inferior direction as well as the left to right direction. The lateral film obtained gives us the anterior-posterior shift information. By using the image-guided technique for daily setup, the most accurate reproducibility of the patient positioning in reference to the simulation is possible. In addition to daily imaging, the standard immobilization may be complimented with some other immobilization devices. Some treatment sites may require more rigid devices to immobilize the patient further such as a bite-block to keep the tongue out of the treatment field for head and neck patients along with an aquaplast mask or a rectal balloon marker to immobilize the prostate from day to day. For targets in areas such as the lung where the target motion is greater, special imaging during simulation is used to provide data that captures the motion. Sometimes implanted fiducials are also used to aid in daily alignment. ADVANTAGES OF PROTON THERAPY As previously mentioned in the differences of proton therapy, this particular particle therapy offers a much lower exit dose as traditional therapy. Although the doses received by the surrounding critical structures from photon treatments are entirely acceptable, we have the ability to decrease the dose to normal structure doses further. Patients who have had previous irradiation and pediatric patients can
www.radiologynursing.org
117
Riley
JOURNAL OF RADIOLOGY NURSING
especially benefit from proton therapy. This unique characteristic of being able to stop the beam allows the medical dosimetrist (person who makes the treatment plan) to place the beam angles at locations that spare the adjacent normal tissue. Sometimes when a patient has recurrent disease, the amount of dose that has already been delivered to the surrounding structures is at their maximum dose tolerance. By having the ability to re-treat using proton beams, staff can re-treat the area that has recurred and not give any more doses or very minimal doses to the structure that has already received a high dose. This is truly amazing for the patients because there are situations when a patient has recurrent disease, some surrounding critical structures have received the maximum allowable dose and they just have not had options for further radiation therapy. For pediatric patients, this treatment technique is even more amazing. Again, while treating the target region, for example, medulloblastoma, it is impossible to not get dose into other areas of the body. Medulloblastoma is a pediatric brain tumor that requires treating of the entire brain and spinal canal. When treating the spinal canal in small children, low dose is often deposited into the abdominal region. Radiation in the abdominal area usually causes side effects such as nausea, vomiting, and diarrhea. By using proton therapy, now we can stop
Proton Therapy
the dose before it gets into the abdomen thereby giving the patients a better quality of life during their treatments. Furthermore, it has been shown that radiation in children may cause secondary malignancies. Miralbell et al. (2002) have reported a decrease in chances of developing a secondary malignancy when using proton therapy for medulloblastoma by a factor of 10. In the neck region, for example, we are able to spare the thyroid with proton radiotherapy in craniospinal treatments for medulloblastoma (Figure 5). It is also of merit to mention the effects of bone growth deformation in children that have received radiation therapy. In long-term follow-up of children who have survived medulloblastoma, it has been noted that their heads and vertebra are reduced in size relative to their limbs that continued to grow normally. Although it is rewarding to know we have cured the patient, we leave a less than desirable wake of lifelong challenges that the patient must contend with. Often children will have stunted or malformed bones in the area of radiation; retinoblastoma, although unusual, is the most common eye cancer in children. This disease is often treated by radiation therapy and leaves the child with bone deformation around the orbital area. These are just a couple of examples of how advantageous proton therapy can be in certain diseases (Figures 6e8).
Figure 5. Seven-year-old patient with medulloblastoma.
118
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JOURNAL OF RADIOLOGY NURSING
Riley
Figure 6. Fourteen-year-old patient with a chordoma cancer.
WORKING IN A PROTON THERAPY CENTER Just like any other medical facility, it takes an entire team of highly skilled and committed employees to make it successful. Many aspects of working in such a facility are much like working in any other center that provides radiation therapy. One of the newest tasks that M. D. Anderson is embarking on at their Proton Therapy Center is the concept of hybrid nursing. What this means for our nurses is that if they were strictly clinical or strictly research before coming to the proton center, they now have to learn and apply both of these competencies together for our patients. All patients treated at PTCH are treated on a therapeutic protocol. There are theoretical reports regarding the outcomes of patients having been treated with protons; however, there has not been a significant amount of clinical data reported to substantiate these theories. It
is necessary and almost mandatory for new proton centers to have all patients on a protocol to clarify any ambiguous findings. It is of enormous value to have all patients on a theoretical protocol to diligently gather, document, and analyze the patient’s short-term and long-term side effects. To analyze data collected on patients, it is necessary that facilities have permission from the Institutional Review Board. This is applicable to prospective studies and retrospective data collection. Although it is indeed challenging in all staff positions to decide to take on this challenge of participating in new technology, it is both rewarding and testing at times. The way the treatments are delivered is a bit different from traditional radiation so the radiation therapists have had to learn new techniques and the medical dosimetrists learning new treatment planning aspects. M. D. Anderson is a leader in cancer care
Figure 7. Seven-year-old patient with Rhabdomyosarcoma.
VOLUME 26 ISSUE 4
www.radiologynursing.org
119
Riley
JOURNAL OF RADIOLOGY NURSING
Proton Therapy
Figure 8. Prostate plans comparing photon intensity-modulated radiation therapy and protons.
and research and we aim to continue to provide leadership and guidance in this newly evolving modality.
References Breuer, H., & Smit, B.J. (2000). Proton therapy and radiosurgery. New York: Springer.
120
Miralbell, R., Lomax, A., Cella, L., & Schneider, U. (2002). Potential reduction of the incidence of radiation-induced second cancers by using proton beams in the treatment of pediatric tumors. International Journal of Radiation Oncology, Biology, Physics, 54(3), 824-829. Webb, S. (1993). The physics of proton radiotherapy. The physics of three-dimensional radiation therapy. London: Institute of Physics Publishing.
www.radiologynursing.org
DECEMBER 2007
SO, WHAT ARE PROTONS ANYWAY AND HOW ARE THEY USED FOR CANCER TREATMENTS? The center of every atom has protons and neutrons that compose the nucleus. The nucleus of the atom is surrounded by electrons (Figure 1). The protons must be made into a form that is useful for cancer treatments. Only accelerators can produce protons with a sufficient enough intensity for therapeutic use (Breuer & Smit, 2000). There are two different types of accelerators that are used for clinical treatment, a cyclotron or a synchrotron. Cyclotrons are linear accelerators that produce a fixed energy, typically a higher energy of about 250 MeV. A synchrotron is a similar machine but has the ability to produce varied energies, usually in the range of 70e250 MeV. Protons are positively charged particles obtained by a hydrogen atom being injected into an electrical field where it is separated into protons and electrons. The protons are sent through a vacuum tube into the linear accelerator and the proton’s energy is boosted to about 7 MV. When the proton beam enters the synchrotron (this is what we have at M. D. Anderson Proton Therapy Center), it is accelerated to reach energies ranging from 70 to 250 MeV, and this is enough energy to place the protons at any depth within the patient’s body. The beam is then passed through a series of magnets which shape, focus, and direct the beam to the individual
Beverly Riley, CMD, is with M. D. Anderson Proton Therapy Center, Houston, TX 77054, USA. Address reprint requests to Beverly Riley, M. D. Anderson Proton Therapy Center, 1840 Old Spanish Trail, Houston, TX 77054, USA. E-mail: [email protected] 1546-0843/$32.00 Copyright Ó 2007 by the American Radiological Nurses Association. doi: 10.1016/j.jradnu.2007.09.001
VOLUME 26 ISSUE 4
treatment rooms. The individual Bragg peaks generated are too narrow to use for treatment, therefore the Bragg peaks are summed up and spread out (SOBP) to a useful plateau (Figure 3). PROTON THERAPY: HISTORICAL BACKGROUND Proton therapy has been used for cancer treatment since 1940s. In 1946, Robert Wilson, ‘‘The Father of Proton Therapy’’ suggested that protons might have a role in cancer treatment because of their advantageous dose distributions. Proton beam range is characterized by dose that rises sharply to a peak and then falls to zero at the end of the range; the shallow region, entrance area displays a relatively low dose (Figure 2). Wilson also proposed the use of range modulator wheels. This allows for the pristine Bragg peaks to be spread out (SOBP) to a more useful width to cover larger tumors (Figure 3). E. O. Lawrence won the Nobel Prize in 1939 for his contributions to the development of the cyclotron at the University of California Lawrence Berkeley Laboratory (LBL). C. A. Tobias, J. H. Lawrence and others were the first to actually use proton beams for treatment on human patients. These treatments were carried out at LBL in the 1950s on the 184-inch cyclotron. Proton therapy treatments continued on this cyclotron until 1992. Much work in proton therapy across the world continued to develop from the 1960s throughout the 1990s. Uppsala, Sweden developed radiosurgery techniques for the treatment of brain tumors and they became the first to use range modulation to achieve an SOBP to conform the dose along the beam path. Dr. Ray Kjellberg of Massachusetts General Hospital began treating small intracranial lesions in 1961 at the
www.radiologynursing.org
115
Riley
Proton Therapy
JOURNAL OF RADIOLOGY NURSING 1.2
Relative Dose
1 0.8 0.6 0.4 0.2 0
6
7
8
9
10
11
12
13
14
15
Depth
Figure 3. Expanded Bragg peak.
Figure 1. Structure of an otom with its subatomic particles. (Courtesy of M. D. Anderson Cancer Center).
Harvard Cyclotron Laboratory in Cambridge, MA and many of the techniques developed there are still used today at The Frances H. Burr Proton Therapy Center in Boston, MA. Between 1968 and 1975, Russia was extremely active with proton therapy at The Joint Institute for Nuclear Research in Dubna and the Moscow Institute for Theoretical and Experimental Physics. Chiba, in Japan, later in the 1970s started treatment at the National Institute for Radiological Sciences. Clatterbridge, England, and Nice and Orsay, France both started programs as well as iThemba Labs in Cape Town, Africa, National Cancer Center in Kashiwa, Japan, and Dubna, Russia. Loma Linda University Medical Center was the first hospital-based proton therapy center located in Loma Linda, CA and began treating patients in 1990. This
was the first facility to have rotating gantries which enable treating from any angle much like a modern linear accelerator. Their facility has treated the most number of patients of all proton therapy centers to date. In the most recent years, three more proton centers have been opened in the United States, The Midwest Proton Center in Bloomington, IN, M. D. Anderson Proton Therapy Center in Houston, TX (PTCH), and The Florida Proton Therapy Institute in Jacksonville, FL. Most proton facilities have a fixed beam room which means that only the table moves in addition to having several rotating gantries. M. D. Anderson’s Proton Therapy Center is currently the largest in the nation. There is great desire for these centers to collaborate on patient protocols. A challenge to this lies in the fact that there are no ‘‘set standards’’ or class solutions for proton therapy treatment planning just yet as there is with traditional photon therapy. What this means is that not all plans are designed in the same fashion. There are various ways to achieve treatment plans. But for the protocol to have consistency, it is necessary for facilities to follow more stringent guidelines to aid in more measurable results. However, at M. D. Anderson Proton Therapy Center, every patient is on an in-house protocol. These data will be reviewed retrospectively in the future once a sufficient number of patients have been treated to collect enough data. WHAT MAKES PROTON THERAPY DIFFERENT?
Figure 2. Examples of a depth dose distribution for photons and protons.
116
Proton therapy differs from traditional radiation therapy in that protons have the unique ability to stop at a defined distance, or range. Proton beams enter the body and deposit most of their energy in the tumor region and then stop. The X-ray beams, used in traditional radiation therapy, traverse healthy tissue as well as the tumor and have what is known as exit dose (Figure 4). Although the doses that are given to the normal healthy tissues are within the acceptable dose limits, proton therapy has the ability to decrease
www.radiologynursing.org
DECEMBER 2007
Proton Therapy
JOURNAL OF RADIOLOGY NURSING
Riley
that for traditional photon radiation treatments, the dependence of the materials being traversed by the beam is much less sensitive to the various changes in material composition compared to protons. Proton beams are very sensitive to density changes, and the treatment delivery may be compromised if day-to-day setup is not precise. Therefore, daily imaging is required. IMAGE-GUIDED RADIATION THERAPY
Figure 4. Photon beam displaying exit dose. Proton beam displaying how dose stops.
the dose to these areas. Having the ability to decrease the dose to normal healthy tissue while focusing the dose on the tumor lends itself to the opportunity of increasing dose to the target area. Many types of cancers may have better local control if we have the ability to increase the total dose delivered to the tumor and spare the surrounding normal structures that have historically limited the dose that may be given to the tumor (Webb, 1993). For the most part, proton therapy is basically no different for the patients except for just a few things. All patients must first receive a simulation to receive any type of radiation therapy; this means the patient is to have a treatment planning CT scan. The patients are immobilized based on the area of treatment. Immobilization varies by the body part being treated in that more restrictive devices may be used for areas that tend to move more easily such as the head region. It is of utmost importance that the patients be set up each day in the exact same position with respect to the simulation using the same devices. This allows for the most accurate treatment delivery because the treatment plans generated are done so by using the CT data obtained during simulation. The main difference here is VOLUME 26 ISSUE 4
Image guidance to assist in daily setup for radiation therapy treatments is of great interest at this time. Historically, this has been used in proton therapy because of the precision required for particle therapy. Proper alignment of the target area could only be achieved this way. Today, 2 kV X-ray images are obtained before the treatment delivery to aid in setup. For example, to treat a prostate patient, each day the radiation therapist will take an image from the anterior-posterior projection (AP) and one from the left or right lateral position. These images are then aligned to the treatment planning images created from the simulation data using a sophisticated imaging alignment system. These images are coregistered to one another using identifiable anatomical landmarks. The AP image provides data needed to move the patient in the superior-inferior direction as well as the left to right direction. The lateral film obtained gives us the anterior-posterior shift information. By using the image-guided technique for daily setup, the most accurate reproducibility of the patient positioning in reference to the simulation is possible. In addition to daily imaging, the standard immobilization may be complimented with some other immobilization devices. Some treatment sites may require more rigid devices to immobilize the patient further such as a bite-block to keep the tongue out of the treatment field for head and neck patients along with an aquaplast mask or a rectal balloon marker to immobilize the prostate from day to day. For targets in areas such as the lung where the target motion is greater, special imaging during simulation is used to provide data that captures the motion. Sometimes implanted fiducials are also used to aid in daily alignment. ADVANTAGES OF PROTON THERAPY As previously mentioned in the differences of proton therapy, this particular particle therapy offers a much lower exit dose as traditional therapy. Although the doses received by the surrounding critical structures from photon treatments are entirely acceptable, we have the ability to decrease the dose to normal structure doses further. Patients who have had previous irradiation and pediatric patients can
www.radiologynursing.org
117
Riley
JOURNAL OF RADIOLOGY NURSING
especially benefit from proton therapy. This unique characteristic of being able to stop the beam allows the medical dosimetrist (person who makes the treatment plan) to place the beam angles at locations that spare the adjacent normal tissue. Sometimes when a patient has recurrent disease, the amount of dose that has already been delivered to the surrounding structures is at their maximum dose tolerance. By having the ability to re-treat using proton beams, staff can re-treat the area that has recurred and not give any more doses or very minimal doses to the structure that has already received a high dose. This is truly amazing for the patients because there are situations when a patient has recurrent disease, some surrounding critical structures have received the maximum allowable dose and they just have not had options for further radiation therapy. For pediatric patients, this treatment technique is even more amazing. Again, while treating the target region, for example, medulloblastoma, it is impossible to not get dose into other areas of the body. Medulloblastoma is a pediatric brain tumor that requires treating of the entire brain and spinal canal. When treating the spinal canal in small children, low dose is often deposited into the abdominal region. Radiation in the abdominal area usually causes side effects such as nausea, vomiting, and diarrhea. By using proton therapy, now we can stop
Proton Therapy
the dose before it gets into the abdomen thereby giving the patients a better quality of life during their treatments. Furthermore, it has been shown that radiation in children may cause secondary malignancies. Miralbell et al. (2002) have reported a decrease in chances of developing a secondary malignancy when using proton therapy for medulloblastoma by a factor of 10. In the neck region, for example, we are able to spare the thyroid with proton radiotherapy in craniospinal treatments for medulloblastoma (Figure 5). It is also of merit to mention the effects of bone growth deformation in children that have received radiation therapy. In long-term follow-up of children who have survived medulloblastoma, it has been noted that their heads and vertebra are reduced in size relative to their limbs that continued to grow normally. Although it is rewarding to know we have cured the patient, we leave a less than desirable wake of lifelong challenges that the patient must contend with. Often children will have stunted or malformed bones in the area of radiation; retinoblastoma, although unusual, is the most common eye cancer in children. This disease is often treated by radiation therapy and leaves the child with bone deformation around the orbital area. These are just a couple of examples of how advantageous proton therapy can be in certain diseases (Figures 6e8).
Figure 5. Seven-year-old patient with medulloblastoma.
118
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DECEMBER 2007
Proton Therapy
JOURNAL OF RADIOLOGY NURSING
Riley
Figure 6. Fourteen-year-old patient with a chordoma cancer.
WORKING IN A PROTON THERAPY CENTER Just like any other medical facility, it takes an entire team of highly skilled and committed employees to make it successful. Many aspects of working in such a facility are much like working in any other center that provides radiation therapy. One of the newest tasks that M. D. Anderson is embarking on at their Proton Therapy Center is the concept of hybrid nursing. What this means for our nurses is that if they were strictly clinical or strictly research before coming to the proton center, they now have to learn and apply both of these competencies together for our patients. All patients treated at PTCH are treated on a therapeutic protocol. There are theoretical reports regarding the outcomes of patients having been treated with protons; however, there has not been a significant amount of clinical data reported to substantiate these theories. It
is necessary and almost mandatory for new proton centers to have all patients on a protocol to clarify any ambiguous findings. It is of enormous value to have all patients on a theoretical protocol to diligently gather, document, and analyze the patient’s short-term and long-term side effects. To analyze data collected on patients, it is necessary that facilities have permission from the Institutional Review Board. This is applicable to prospective studies and retrospective data collection. Although it is indeed challenging in all staff positions to decide to take on this challenge of participating in new technology, it is both rewarding and testing at times. The way the treatments are delivered is a bit different from traditional radiation so the radiation therapists have had to learn new techniques and the medical dosimetrists learning new treatment planning aspects. M. D. Anderson is a leader in cancer care
Figure 7. Seven-year-old patient with Rhabdomyosarcoma.
VOLUME 26 ISSUE 4
www.radiologynursing.org
119
Riley
JOURNAL OF RADIOLOGY NURSING
Proton Therapy
Figure 8. Prostate plans comparing photon intensity-modulated radiation therapy and protons.
and research and we aim to continue to provide leadership and guidance in this newly evolving modality.
References Breuer, H., & Smit, B.J. (2000). Proton therapy and radiosurgery. New York: Springer.
120
Miralbell, R., Lomax, A., Cella, L., & Schneider, U. (2002). Potential reduction of the incidence of radiation-induced second cancers by using proton beams in the treatment of pediatric tumors. International Journal of Radiation Oncology, Biology, Physics, 54(3), 824-829. Webb, S. (1993). The physics of proton radiotherapy. The physics of three-dimensional radiation therapy. London: Institute of Physics Publishing.
www.radiologynursing.org
DECEMBER 2007